Channel Scanning

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Revision as of 18:04, 9 June 2022 by Kdewaal (talk | contribs) (→‎Unicable configuration)

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Version:
32
 This HOWTO is up to date for MythTV Version 32. For previous versions

this guide can also be used but some differences may be encountered.

Contents

How to do Channel Scanning

After doing the basic MythTV installation with network setup, storage directories and so on there comes the moment to find out which channels can be received. For DVB and ATSC the MythTV application mythtv-setup can do Channel Scanning, a process by which all channels that can be received are identified and stored in the database. Mythtv-setup is a separate application that can only run when mythbackend is not running because it needs the same tuner devices that mythbackend uses to make recordings. This guide describes how to do channel scanning with mythtv-setup.

But before we do that first a bit of explanation about the terminology.

What is a Video source 

The TV signal usually comes via a coaxial cable. This cable can come from a provider such as a DVB-C cable signal, or it can be linked to a DVB-T/T2 antenna or to a satellite dish for DVB-S/S2. In MythTV, the Video source does represent such an input signal. The result of the channel scan, a list of channels, is attached to the video source.

What is a Capture card 

To receive TV a tuner device is needed. This can be for example a PCIe card, an USB device or a networked tuner such as a HDHomeRun box. In MythTV a tuner is called a capture card. There can be two or more tuners on one card; these are then separate capture cards in MythTV.

What is an Input connection 

An input connection connects a capture card to a video source. The video source has the channel list so only via this connection the capture card has the information to tune to a channel. Remember that the Video Sources and the Input Connections are just software abstractions that enable a single list of channels to be shared among multiple tuners.

How the GUI works 

The GUI is intended to be used with a minimum of remote control keys: up, down, left, right, enter and exit. The remote control keys are mapped to keyboard keys and that is what is used with mythtv-setup. It is not possible to navigate through all the menu's with a mouse and mouse clicks.

The mythtv-setup start page consists of a number of lines with items to be selected. The currently selected one is highlighted. With the up/down arrow keys another line can be selected.
A selection can be activated by pressing the space bar. This means that something actually happens. For instance, if the entry 2. Capture card is highlighted then after pressing the space bar the Capture cards page is shown.

If there is a right arrow ">" shown at the end of the line then pressing the right arrow key brings you to the next menu level; pressing the left arrow key "<" brings you back to the previous menu level.

In lists you can delete items by pressing the "D" key on a selected item. For instance, if you have selected (highlighted) an entry in the list of capture cards then you can delete that capture card by pressing the "D" key. After pressing the "D" key there is always a popup menu asking for confirmation before it is really deleted. Pressing the "M" key on a list item can show a menu, usually with choices "Edit" and "Delete".

The escape key ("Esc" or "esc" on keyboards) gives a dialog box with "Save then Exit" as first choice. This needs to be selected, by pressing the space bar or the Enter key, to save the choices made. You then also drop back to the previous menu or even to the menu before that.

If you have made a selection and need to make another from the previous menu page then use the left-arrow key "<" to go back.

DVB-T/T2 configuration

Starting in the mythtv-setup main menu page, this are the steps to take. The steps described are for a DVB-T/T2 tuner but there are not many differences with other tuner types.

  • Main menu of mythtv-setup

2. Capture card

Select the first choice: (New capture card)
This gives a new entry at the bottom of the list: New capture card
Note that this entry is without the brackets.

  • No capture card created yet

  • Configure new capture card

Select the New capture card and press the right arrow key.

  • Select card type of new capture card

  • Popup list with all possible card types

There is now a single line Card type with a popup list of possible card types. The default value, and the one that is used in this example, is the DVB-T/S/C, ATSC or ISDB-T tuner card.

  • Capture card configuration

  • Select delivery system

DVB device

The first line with label DVB device has a pop-up list of possible devices. The first DVB device typically shows up as /dev/dvb/adapter0/frontend0. If you have only one tuner card then life is easy otherwise you do have to know which tuner you have to choose. To help with this the second line shows the Frontend ID. Also the third line that shows which delivery systems are supported by this card can help you to select the correct tuner card.

Frontend ID

Information read from the tuner card. This can help with identifying the correct tuner card if there are more than one.

Delivery system

The type of DVB, such as DVB-T2 or DVB-C, is called a delivery system. There are capture cards that can receive multiple delivery systems. The popup menu shows the delivery systems that your capture card supports. If you want to receive a DVB-T or a DVB-T2 signal then select DVB-T2. If you want to receive a DVB-S or a DVB-S2 signal then select DVB-S2. For DVB-C you should probably always select DVB-C/A.

Signal timeout (ms)

Leave this at the default value. If there are problems with channels not being found this value can be increased to 10000ms. This can be necessary with networked tuners such as HDHomeRun devices.

Tuning timeout (ms)

Leave this at the default value. If there are problems with channels not being found this value can be increased up to 20000ms (20 seconds). For non-encrypted channels this is always long enough. Some TV cards with a Conditional Access Module (CAM) and a smartcard may need up to 20 seconds. Also networked tuners such as the HDHomeRun devices may need this long.

Wait for SEQ start header

Leave at default (option is checked).

Open DVB card on demand

Leave at default (option is checked).

Use DVB card for active EIT scan

If you will use Schedules Direct or another source of guide data then uncheck this option. If you want to use the EIT to get the guide data then leave this option checked. If you have more than one capture card connected to the same video source then you need to select Use DVB card for active EIT scan only for one card.

DiSEqC (Switch, LNB and Rotor Configuration)

This option only appears if you have selected a DVB-S/S2 tuner device. More on this later as the current example is for DVB-T2.

  • Exit dialog after capture card configuration

Now that the capture card is configured, press the ESC (escape) key. In the popup menu select Save then Exit. Only if you do the Save then Exit the information is actually written to the database.


3. Recording Profiles

The options in this page are not for the channel scan itself but are used when making recordings.
Per tuner type recording profiles can be configured. The profiles Default and Live TV are used by default.
A useful value that can be configured is the Recording Type which can be set to Normal, TV Only or Audio Only. This determines which components of the program will be recorded.
The default is Normal which means that all components of the program will be recorded. This consists of the video, audio and subtitle streams but also, when present, streams that support interactive television such as MHEG and HbbTV. MHEG is present in the BBC programs that are broadcast on FreeSat and Freeview. The amount of data can be considerable; in a BBC recording up to 40% of the size of the recording can be used for MHEG. If the interactivity is not used storage space can be saved by selecting the TV Only recording type; in TV Only only the video, audio and subtitle streams are recorded.

The option "Record Full TS?", when selected, will cause each recording to be accompanied by an additional file with the same name as the recording followed by ".raw". This file contains the full transport stream of which the recording was made. This feature is only present for development use.

4. Video sources

Select the first choice: (New video source)
This gives a new entry at the bottom of the list: New video source
Note that this entry is without the brackets.

  • No video source created yet

  • Configure new video source

Select New video source and press the right arrow key.
This shows now the New video source page with a number of items to fill in.

  • Video source configuration

  • Enter name of the video source

Video source name

Anything can be used as the video source name but there must be something. The name of the provider, e.g. digitenne or Freeview is a good choice.

Listings grabber

Default is Transmitted guide only (EIT). If the package xmltv is installed then there is a choice of other methods to get guide data. The quality of the EIT guide data tends to be good in Europe but not very good in the United Status, where the commercial Schedules Direct service is widely used.

Channel frequency table

This can usually be left at the default value (which is default) in which case the value defined in the General / Locale settings will be used. It is possible to override that default here for only this video source. This can be useful if you have one video source for cable and another video source for broadcast (terrestrial).

For ATSC this value is used as default for the frequency table selection option in the Channel Scan / Scan Type: Full Scan options (see ATSC Configuration).

Scan Frequency

This is the frequency that is used as the default value for a Full Scan (Tuned) channel scan. This is needed for a DVB-S/S2 or a DVB-C scan because there you start tuning on a pre-defined frequency; from the signal on that frequency all the information about the other frequencies is obtained. For DVB-C this frequency is specified by the provider. For satellite the frequencies can be found on lyngsat.com. More about DVB-S/S2 scanning later in this guide. For DVB-T/T2 usually a Full Scan is done which scans all frequencies so then this field can be left empty.

Network ID

This is used only with DVB-C. Your provider has given you not only an initial frequency but also the network ID to use. In DVB-C a multiplex (transport stream) can be transmitted on different frequencies in different regions. The frequency information is for each region stored in a separate NIT (Network Information Table). The Network ID selects the NIT that will be used.

Bouquet ID

Select the bouquet ID for Freesat or Sky on satellite Astra-2 28.2E. The bouquet ID and the region ID are needed to get the Freesat or Sky channel numbers. More about this on page DVB UK. Getting the channel numbers may also work on the other Sky satellites, provided you have given the correct bouquet ID for your satellite and your region. Leave this at 0 if this video source is not used to receive a Sky satellite.

Region ID

Select the region ID for Freesat or Sky on satellite Astra-2 28.2E. This is needed to get the Freesat or Sky channel numbers correct for your region, provided you have also entered a correct bouquet ID. More about this on page DVB UK. Leave this at 0 if this video source is not used to receive this satellite.

Now that the video source is configured, press the ESC (escape) key. In the popup menu select Save then Exit. Only if you do the Save then Exit the information is actually written to the database.

Logical Channel Number Offset

The offset specified here is added to each logical channel number found in this video source. For example, if the logical channel numbers are from 1 to 1000 then by specifying an offset of 1000 the resulting channel numbers will be from 1001 to 2000. This makes it possible to give different video sources a non-overlapping range of channel numbers. Leave at 0 if you have only one video source or if the video source does not have logical channel numbers.

5. Input connections

This page shows a list of all capture cards and to which video source each capture card is connected. If there is no video source selected yet then (None) is shown.

  • Select capture card for input connection

  • Input connection configuration page

  • After selecting the video source

  • Input connection configuration page, second part

Select the capture card and press the right arrow key.

Delivery system

This shows the delivery system (modulation), for instance DVB-T2, that you have selected when you configured the capture card. The value cannot be changed here.

Display name

It is for some themes important that the last two characters of the name are unique. The default name is something like Input 1 and this name is guaranteed to be unique. If you have a lot of different capture cards then names like T0, T1 for the DVB-T2 tuners and C0, C1 for the DVB-C tuners are both short, descriptive and unique.

Video source

Default is (None) and this needs to be changed. Press the space bar and select a video source.

Use quick tuning

Leave at default (Never).

Use DishNet long-term EIT data

Leave at default (not checked) unless you receive the DishNet satellites.

Scan for channels

If you press the space bar here you enter the Channel Scan dialog. This is what we want but first the other fields in the page are described.

Fetch channels from listings source

This is an alternative way of getting your channel configuration. It could be that this does not work at all. Skip this if you want to do a channel scan.

Starting channel

This is the channel that is tuned to when Watch TV is selected in the mythfrontend main menu page. The popup list lets you choose one of the existing channels so this can be done only after the channel scan is completed. This value is not very important; if it is not a valid channel then possibly Watch TV fails when it is used the first time. In that case go to the program guide, select a channel, press Enter and choose "Watch this channel". This channel is then saved and will be the starting channel the next time Watch TV is selected.

Interactions between inputs

The options in this page are not for the channel scan itself but are used when making recordings.

  • Interactions between inputs

Max Recordings

The maximum number of recordings that can be simultaneously made from this input. This is relevant for the inputs that can receive the complete transport stream, which are the DVB (/dev/dvb/*/*), HDHomeRun and SatIP tuners. For all other tuners keep this value to the default of 1. For each simultaneous recording a tuner is needed; when the Max Recordings is e.g. set to 4 then there will be 3 additional virtual tuners created. The capability to receive more than one channel from one transport stream is called Multirec in MythTV terminology.

Schedule as Group

When this option is checked additional virtual tuners are created dynamically when needed. In this case the Max Recordings setting can be left to 1. This option is checked by default. When the tuner is not capable of Multirec then uncheck this option and set the Max Recordings to 1. Tuner cards that can receive encrypted channels with a Conditional Access Module and a smartcard are also limited by the number of channels that can be simultaneously decrypted by the Conditional Access Module. For these cards it is advised to uncheck this option and to set Max Recordings to the maximum number of channels that can be simultaneously decrypted. This is usually at least two.

Input Priority

If the input priority is not equal for all inputs, the scheduler may choose to record a show at a later time so that it can record on an input with a higher value. The default value is 0. It is possible to enter both negative and positive values but it is recommended to use only positive values because some versions of the SQL database used by MythTV do fail on negative values.

Schedule Order

If priorities and other factors are equal the scheduler will choose the available input with the lowest, non-zero value. Setting this value to 0 will make the input unavailable to the scheduler so no recordings will then be made from this input. It is however possible to watch live TV when the value is 0. The default value is 1.

Live TV Order

When entering Live TV, the available local input with the lowest non-zero value will be used. If there are no local inputs available then the available remote input with the lowest non-zero value will be used. Setting this value to 0 will make the input unavailable for Live TV. However, it is possible to schedule recordings when the value is 0. The default value is 1.

Create a new Input Group

Input groups are only needed when two or more cards share the same resource such as a Firewire card and an analog card input controlling the same set top box.

Input Group 1

Leave as "Generic" unless the input is shared with another device. Only one of the inputs of a given input group will be allowed to record at any given time.


This completes the configuration of the capture card. There are more choices to be made for a channel scan but these choices are not part of the capture card. The configuration of the capture card is stored in the database when you select Save then Exit as soon as this dialog box appears.

Now, after pressing the "Scan for channels", the page "Channel Scan" appears.

Channel Scan

The Channel Scan page has many options that have a great influence on the final channel list. The examples here are for DVB-T2 but for DVB-C and DVB-S/S2 the options are the same.

  • Channel Scan options, part 1

  • Channel Scan options, part 2

  • Scan type selection

  • Select multiplex for scan of single transport


Important.png Note: All the Channel Scan options are used ONLY for this scan. The choices made are NOT saved in the database and for the next scan the options have to be set again.

Desired Services

A typical signal can have not only TV channels but also radio channels and data channels. The default value is "TV" and then all channels that are not TV are discarded.

Unencrypted Only

This option is by default checked; it means that all encrypted channels are discarded and only the free-to-air channels which do not need to be decrypted are kept. Uncheck this option only if you do have the decoding hardware, such as a DVB card with a Common Interface, a Conditional Access Module (CAM) and an activated smartcard.

Logical Channel Numbers required

The logical channel number information is sent by the broadcaster to set the channel numbers to nice values. If there are logical channel numbers in the signal then MythTV will always use them. If this option is checked, all channels that do not have a logical channel number are discarded. This is useful to filter out services for set-top-box firmware download and video-on-demand that can be present on a DVB-C signal but that never have a logical channel number assigned to them.
This option is by default unchecked.

Complete scan data required

This option discards all channels that do not have all required data. An example is a DVB channel that does not appear in the SDT (service description table) or that does not appear in both the PAT (program allocation table) and the PMT (program map table). On satellites there are many incomplete channels that are used for feeds or that are offline.
This option is checked by default.

Full search for old channels

If this option is set, each scanned channel is compared with all channels in the database to see if the scanned channel is an update of an existing channel or if it is a new channel. If this option is not set, each scanned channel is only compared with the channels in the same multiplex.
This option is checked by default.

Remove duplicates

If this option is set, duplicate transports are discarded. After the scan is done, all transports found are compared and when identical transports are found on different frequencies the transport with the best signal is kept and the other is discarded. This is useful for DVB-T2 and ATSC/OTA when a transport can sometimes be received from different transmitters.
This option is checked by default.

Add full Transport Stream channels

The full transport stream contains everything that is received from the tuner. The full transport stream is also called the multiplex because it contains a number of TV and/or radio channels multiplexed together in one stream of bits. Creating a synthetic channel for this, e.g. MPTS_2300 or so, makes it possible to record it with mythtv. A full transport stream recording is typically used as input to a stream analyzer such as DVB Inspector which can tell you what every bit and byte in the stream means. This information can be used by developers to debug and enhance mythtv channel scanning and recording.
This option is unchecked by default.

Test Decryptability

Test all scanned channels to see if they can be decrypted with the installed Conditional Access Module (CAM) and smartcard. This can be useful because sometimes the flag in the signal that indicates an encrypted signal is not correct. However, this check takes a very long time. This option is unchecked by default and it is recommended to leave it unchecked.

Video Source

This field shows the video source that is attached to the capture card. It is possible to change the video source here to any other video source that has a capture card connected to it.

Input

This field shows the currently selected capture card. If there are multiple capture cards connected to the same video source then it is possible to select any one of these capture cards.

Scan Type

The scan type can be selected with a popup menu. The default choice depends on the selected delivery system.

Full Scan

This is the default choice for DVB-T/T2. With this option a list of frequencies on which multiplexes can be found is scanned. The list of frequencies can vary because each country can decide which part of the spectrum is available for broadcast.
Now, pressing the right arrow key shows a country. This is a popup list; select the correct country. If your country is not present then select a country nearby and see what happens. After making the selection press the left arrow key to go back to the Channel Scan page. This scan takes a lot of time because it tries all possible frequencies but it is the only way for DVB-T/T2 if you start with a clean slate. If you forget to select your country then usually Australia is used as default, which may or may not be what you want.
For the curious, the default value for the country selection is from database table Settings, value "Country". This value is defined with the initial MythTV configuration when country and language can be selected. It is possible to later change the language with the GUI but that is not possible for the country.
The country selection can be changed directly in the database. If you do that then mythtv-setup must be started twice because the value is cached in .mythtv/cache/contextcache.xml, the cached values take precedence at startup over the values in the database and only after startup the contextcache.xml is updated from the values in the database.

Full Scan (Tuned)

This is the default choice for DVB-C and DVB-S/S2. Pressing the right arrow key ">" shows a page in which the modulation parameters, needed to tune to the first multiplex, have to be specified. After entering the modulation parameters press the left arrow key "<" to get back to the previous menu. Do NOT press Escape as this discards all entered values.
With DVB-C and DVB-S/S2 the first multiplex does contain enough information to find all other multiplexes. With DVB-T/T2 this is usually not the case; if you use the Full Scan (Tuned) you will get all the channels of the specified multiplex but you may not find the other multiplexes.

Import existing scan

For each video source the last 10 scans are saved for some time. With this option you can process and store the results of a previous scan again. This is extremely useful if a scan takes a long time and you want to see the results of different processing options, for example to see what happens when the "Complete scan data required" is unchecked or when a different region ID is selected.
This option is now available in MythTV version 32; in previous versions the option was present but it did not work.

Scan of all existing transports

This is the option that is recommended for a rescan. Channels do disappear and new channels appear from time to time but the multiplexes usually change less frequent. For DVB-T/T2 this is a good choice because it avoids wasting time on frequencies where there is nothing to receive.

Scan of single existing transport

After this is selected, press the right arrow key to get the menu page in which the multiplex can be selected. The first field can be used to select the multiplex with a popup menu. Default is the first multiplex.
The next field is "Ignore signal timeout". This can usually be left unchecked. If it is needed then it might be a good idea to increase the signal timeout value for that capture card.
The last field is "Search new Transports". If this option is checked then new transports will be added to the video source when the NIT (network information table) in the selected multiplex does have this information.

Scan

Pressing the space bar does actually start the scan and shows the SCANNING page!!!

Scanning

This page shows the scanning progress. At the right/top corner you see ":Found: 50" which is the number of channels found so far. This is what is called the number of "probable channels" which includes all channels that are later filtered out, such as incomplete channels and data channels, depending on the options given.

  • Scanning in progress

  • Scanning finished

When the scanning is ready there comes a popup box that, if the scanning is successful, says something like Found 33 new DVB channels. Select Insert All and then all channels are stored in the database.

The possible choices in this popup box does depend on the success of the scan and if the channels found are already in the database. As an example, let us redo the same scan but with different scan parameters. The DVB-T2 source scanned in the example has 33 TV channels of which 5 are free-to-air (not encrypted) and 28 are encrypted.

Selecting the scan option Unencrypted only and doing a new scan gives the following results:

  • Off-air channels are in the database but not found in the scan

  • Scanned channels found in the database

The 28 encrypted channels are now filtered out by the "Unencrypted only" option. These channels are now classified as "off-air channels", which are the channels in the database that are not found in the scan. Selecting "Delete All" will indeed delete these channels. Be very careful with deleting channels as they cannot easily be undeleted. When in doubt, check the scan parameters and scan again to make sure that the channels are really gone. In real life, if you rescan once or twice a year, only a few channels are gone and a few new channels are found, so a large number of off-air channels is usually an indication something is wrong.

The 5 free-to-air channels are found in the database and are classified as "old" channels. Selecting "Update All" will update the database with the values from the scan and "Ignore All" does not do this. There is a subtle difference between updating and ignoring but generally the "Update All" is the recommended choice.

When you are ready, press the Escape key (ESC) and select Save then Exit until the main menu appears. Saving is essential otherwise the channels are not stored in the database.

Duplicate multiplexes on DVB-T/T2

To get complete coverage TV signals are broadcast on a number of transmitters spread over the country. Transmitters of adjacent regions use different frequencies to avoid interference. Depending on where you live it is thus possible to receive exactly the same transport stream multiplex on two different frequencies. If this happens then mythtv-setup selects the transport with the best signal and discards the other one.
One Full Scan is expected to give the correct channel list.

If the option Remove Duplicates is unchecked or when using an older version of MythTV then mythtv-setup just stores all multiplexes and all received channels which means that the channel list will have duplicates. In that case proceed with the procedure described below.

The best way is to figure out from other sources which transmitter and which frequencies are to be used in your region. Then delete all the transports that you do not want to receive. This can be done with the Transport Editor; a transport can be deleted by pressing the key "D". Then, back in the Channel Scan page, delete all channels and do a Full scan of all existing transports. This will create the correct channel list.

Once the list of transports is correct it is advised to do only Full scan of all existing transports whenever a rescan is needed to avoid the duplicate transports appearing again. However, when transports move to other frequencies then the Full Scan must be done.

It is not possible to select a scanning range so that the unwanted transports are avoided, such as is possible with the ATSC scanner.

It is also possible to manually add a transport with the Transport Editor and then do a scan of only that transport. This is only practical when there are not too many transports of interest.

DVB-C configuration

Configuration of a DVB-C tuner is largely identical to that of a DVB-T2 tuner so only the differences are described here.

2. Capture card

Delivery system

For DVB-C there are a few different flavors, but the one to select is DVB-C/A, short for DVB-C Annex A.

  • Delivery system selection for DVB-C video source

4. Video sources

In DVB-C a multiplex (transport stream) can be transmitted on different frequencies in different regions. Information about all transport streams for a region is stored in a separate NIT (Network Information Table). The Network ID for a region selects the NIT for that region.

The DVB-C provider specifies a single frequency with a multiplex (transport stream) that does contain all the NITs for all regions. With the network ID the correct NIT can be selected and processed.

So for a DVB-C scan the following information is needed:

  • Initial scan frequency
  • Network ID
  • Modulation type, e.g. QAM-64.

This information is usually also needed for the first scan with a DVB-C TV. These TV's then do get all the channel information from only the multiplex on that frequency, which then takes only about 20 seconds. This is something that MythTV does not yet support; MythTV only adds channels from multiplexes that it has actually received. There are also TV's that do something like a "Full Scan" but then with, optionally, frequency steps of 1 MHz or less instead of the channel bandwidth of 8 MHz. This is not implemented in MythTV.

The initial scan frequency and the network ID are stored in the video source.

  • Configuration for DVB-C provider Ziggo (Netherlands)

The modulation type for the initial frequency is not stored in the video source; the modulation type has to be given the first time a "Full Scan (Tuned)" is done. After a successful scan the modulation type does not need to be entered ever again because it is stored in the database for each multiplex. The initial frequency stored in the video source is sufficient to retrieve all tuning data for new scans.

DVB-S/S2 configuration

Configuration of a DVB-S2 tuner is largely identical to that of a DVB-T2 tuner so only the differences are described here.

2. Capture card

  • Select DVB-S2 frontend

  • Select DVB-S2 delivery system

DVB device

There are capture cards such as the TBS6528 used in this example that support DVB-C/T/T2 and also DVB-S/S2. These cards appear as two devices in Linux and consequently also in MythTV. For the TBS6528, device /dev/dvb/adaptorX/frontend0 is for DVB-C/T/T2 and /dev/dvb/adapterX/frontend1 is for DVB-S2. Check the list of possible delivery systems to make sure the correct frontend is selected.
If the card has two different input connectors it is physically possible to connect a DVB-T2 and a DVB-S2 simultaneously. In that case it is possible to configure both frontend0 and frontend1 and both devices can be used, although not at the same time. These cards are really one device with two inputs of which only one can be used at a given moment. MythTV does actually support this in the scheduler.
There is an issue with the EPG capture via EIT; this is currently supported only on one frontend per card. In this example it is possible to configure EIT for the DVB-T2 device or for the DVB-S2 device but not for both.

Delivery system

If you card is capable of DVB-S2 then this is the default; leave it a DVB-S2 and then both DVB-S and DVB-S2 transport streams can be received. When your capture card is old it is possible it can only support DVB-S.

  • DVB-S/S2 input configuration

  • Select what is connected to the input

DiSEqC (Switch, LNB and Rotor Configuration)

If this is left at the default Unconnected then the DVB-S2 card will not receive anything at all.
The other possible values are:

Switch 

A DiSEqC switch is typically a 4-to-1 multiplex device that allows you to connect 4 different LNBs to one card input. With one card input it is then possible to use one satellite dish with four LNBs, each pointing to a different satellite, or to use four different satellite dishes each with one LNB. Only one LNB can be received at a time. MythTV does not only support DiSEqC switches but also other types.

Rotor 

A rotor can rotate the dish to point to any satellite.

Unicable 

With a Unicable LNB it is possible to use a single cable to supply signals to multiple tuners. See for an introduction the Wikipedia pages Unicable and Single cable distribution. MythTV version 32 supports only the original Unicable/SCR specification which allows up to 8 tuners to be connected to one LNB with a satellite splitter. The newer Unicable II/dCSS/Jess specification allows up to 32 tuners. The Unicable II/dCSS/Jess LNBs also understand the older Unicable/SCR protocol so these are supported by MythTV but only for the first 8 channels.

LNB 

This is the choice when the LNB (low noise block) of the satellite is directly connected to the input of the card.

Unicable configuration

The following screenshots shows how to configure the capture card to use the first userband on 1210MHz.

  • Card Type

  • Input and satellite settings

  • Device Type

  • Unicable Configuration

Userband 

Set Userband to 0 for your first tuner, 1 for second etc. Default value is 0.
There are 3 bits available in the DiSEqC command to select the userband so the range of possible values is from 0 to 7. In LNB documentation the first channel is usually called CH01 (channel one) and in MythTV the value for Userband is then 0.

Frequency 

The frequency in MHz of the userband. Set this to 1210 for your first tuner, 1420 for second etc. Default value is 1210.
The complete frequency table for the original Unicable specification is given here:

Userband Channel Frequency (MHz)
0 CH01 1210
1 CH02 1420
2 CH03 1680
3 CH04 2040
4 CH05 1005
5 CH06 1050
6 CH07 1095
7 CH08 1140
PIN code 

Unicable PIN code (-1 disabled, 0 - 255). The default value is -1.

Repeat Count 

Repeat the DiSEqC tuning command for the LNB. The default value is 1 but this can be increased if needed.
Tuning is done by sending commands via the DiSEqC protocol. There can be multiple tuners connected to the same cable and each tuner can send tuning commands at any time; there is no such thing as collision detection and/or collision avoidance so it is possible that tuning commands get lost. Repeating the command a few times makes it more likely that it arrives at least once.
If the repeat count N is lower than 10, the command will be resend N times. This is done with the repeat flag set.
If the repeat count N is higher than 10, command will be resend N-10 times. This is the command without the repeat flag set.
This can make a difference when the DiSEqC equipment does not support the repeat flag or if the support is broken.

Device Type 

Leave this at the default value of LNB. It is possible to select a specific LNB type that is different from the "Universal (Europe)" but this probably never needed because the actual tuning is done by the electronics in the LNB itself. Most Unicable LNBs also have a legacy connector which behaves like an ordinary LNB. The LNB configuration for the legacy connector should also work with the Unicable configuration.

LNB configuration

The following screen shots show how to configure the LNB type to Universal (Europe) which is also the default. There are a number of preset configurations defined and it is also possible to set the values for your particular system if the presets do not fit your hardware.

  • DisEqC LNB configuration

  • DisEqC LNB configuration

  • LNB preset configuration choices

  • Configuration for LNB type Universal (Europe)

The examples in this document are all done with LNBs configured as Universal (Europe).

4. Video sources

  • Video source with initial scan frequency for Astra-2 on 28.2 East

The only parameter specified here, in addition to giving this video source a name, is the initial scanning frequency. The frequency used in this example, 11426500 kHz (11.4265 GHz) is the home frequency for the UK Freesat satellite broadcasting system. Other frequencies can be found on www.lyngsat.com; for Astra-2 all frequencies, channel names and modulation parameters can be found on page https://www.lyngsat.com/Astra-2E-2F-2G.html.

Another source of information is linuxtv.org; for example, page https://git.linuxtv.org/dtv-scan-tables.git/tree/dvb-s/Astra-2E-28.5E contains the list of transports for the Astra-2E satellite. As this is a git archive the information can be easily downloaded.

Only the initial frequency is stored in the video source; the other modulation parameters have to be given the first time a "Full Scan (Tuned)" is done. After a successful scan the modulation parameters do not need to be entered ever again because they are stored in the database for each multiplex. The initial frequency stored in the video source is sufficient to retrieve all tuning data for new scans.

The Bouquet ID and the Region ID are used to get the Freesat and Sky channel numbers.

DVB-S2 Full Scan (Tuned)

  • DVB-S2 Full Scan (Tuned), Select default tuning parameters

  • DVB-S2 Full Scan (Tuned), Second part of the list

The initial frequency should select a transport stream that carries the information about all other transport streams in the network. On some networks this information is present in every transport stream but that is not always the case. For a number of satellites default values for the initial scan frequency plus tuning parameters can be selected.

The following initial frequencies and scan parameters have been tested.

Satellite Frequency Symbol rate Modulation FEC Delivery system Polarity Roloff
Astra-1 19.2E 11229000 22000000 8PSK 2/3 DVB-S2 Vertical
Astra-1 19.2E 11758500 27500000 QPSK auto DVB-S2 Horizontal
Astra-3B 23.5E 11739000 29900000 8PSK 2/3 DVB-S2 Vertical
Astra-3B 23.5E 12031500 27500000 QPSK auto DVB-S2 Horizontal
Astra-3B 23.5E 12090000 29900000 8PSK 2/3 DVB-S2 Vertical 0.25
Hotbird 13B 13.0E 12015000 27500000 8PSK 3/4 DVB-S2 Horizontal 0.35
Astra-2 28.2E 10714000 22000000 QPSK 5/6 DVB-S Horizontal
Astra-2 28.2E 10847000 23000000 8PSK 3/4 DVB-S2 Vertical
Astra-2 28.2E 11426500 29500000 QPSK 3/4 DVB-S2 Vertical

DiSEqC switch configuration

A typical use is a four-channel DiSEqC switch with each output connected to an LNB as described earlier. It is possible to create complex configuration with switches after switches, some switch outputs connected to an LNB, another switch output connected to a rotor etc etc. The good news is that MythTV does support about any configuration. However, the configuration order is not entirely obvious.

As an example, all configuration steps for a four-LNB satellite system are given here. This is done by creating four almost identical capture card entries that all use the same physical capture card. Each capture card entry is then connected to one of the four LNBs.
It is essential that for all four capture card entries the option Open DVB card on demand is checked in order to be able to change from one LNB to another. This option is checked by default.

The hardware configuration consists of:

  • One DVB-S2 capture card
  • One DiSEqC switch with four input ports
  • Four LNBs, each LNB connected to a DiSEqC switch input port
  • LNB 1 pointed to satellite Hotbird 13E0
  • LNB 2 pointed to satellite Astra-1 19E2
  • LNB 3 pointed to satellite Astra-3B 23E5
  • LNB 4 pointed to satellite Astra-2 28E2


In mythtv-setup create the first capture card, configure a DiSEqC switch and change the number of ports to 4:

  • In Capture Card create a capture card
  • Select the capture card device
  • Select DiSEqC (Switch, LNB and Rotor configuration)
  • For Device Type: select Switch
  • In Switch Configuration:
- Select Switch Type to DiSEqC
- Change Number of Ports to 4
- Press ESC (escape key) and select Save then Exit


For all four ports change the type to LNB:

  • Select the capture card device
  • Select DiSEqC (Switch, LNB and Rotor configuration)
  • For Device Type: select Switch
  • In Switch Configuration:
- Select type LNB for all four ports
- Press ESC (escape key) and select Save then Exit


  • Create four video sources; one for each LNB.
- For LNB 1 video source Hotbird 13E0 with scan frequency 12015000
- For LNB 2 video source Astra-1 19E2 with scan frequency 11229000
- For LNB 3 video source Astra-3B 25E2 with scan frequency 12090000
- For LNB 4 video source Astra-2 28E2 with scan frequency 10714000


  • In Input Connections
- Select capture card (there is only one at this moment)
- In DTV Device Configuration select Port 1 (LNB)
- Select video source Hotbird 13E0 for LNB 1
- Optionally, change the Display Name to something you like, e.g. HB (but it must be unique)
- Press ESC (escape key) and select Save then Exit


Now for the second LNB:

  • In Capture Card create a capture card
  • Select THE SAME capture card device again and ignore the "Warning" in the device list popup menu.
  • Uncheck the option Use DVB card for active EIT scan
  • Press ESC (escape key) and select Save then Exit
  • In Input Connections
- Select capture card (this is the second one in the list)
- In DTV Device Configuration select Port 2 (LNB)
- Select video source Astra-1 19E2 for LNB 2
- Optionally, change the Display Name to something you like, e.g. A1 (but it must be unique)
- Press ESC (escape key) and select Save then Exit


For the third LNB do repeat the last sequence and select Port 3 and the video source for LNB 3.
For the fourth LNB etc etc.

Now it is possible to do a channel scan for each satellite in exactly the same way as if there is only one LNB directly connected to the capture card input.

Note: The option Use DVB card for active EIT scan can only be checked for one of the four satellites. This is a limitation of the current implementation and this may be resolved in the future. In this example configuration this is checked for the first satellite and not for the others but this is arbitrary; it can be any of the four but it can be only one.

Freesat and Sky

How to setup a MythTV system to receive the UK Freesat and Sky channels available on the Astra-2 28.2 East satellites is described in the Wiki page DVB UK.

ATSC configuration

Configuration of an ATSC tuner is largely identical to the configuration of DVB tuners so only the differences are described here.

4. Video sources

In the video source the "Channel frequency table" can be selected. There are entries for various countries but for the USA there are four entries specifying both the USA and a delivery system: "us-bcast", "us-cable", "us-cable-hrc" and "us-cable-irc". If there is a value given here (other than "default") this value does override the Channel frequency table selected in the General / Locale Settings page.

The Channel frequency table specified here is the default value for the Channel frequency table selection in the Scan Type "Full Scan" option.

The values specified in the Video source and in the General / Locale Settings, are stored in the database so they will keep their value, but the values specified in the Scan Type "Full Scan" options are NOT saved and must be specified again for each scan.

  • Channel frequency table selection in Video Source

Channel Scan

  • Select Full Scan for ATSC tuner

  • Channel frequency table for ATSC Full Scan

  • Modulation selection for ATSC Full Scan

  • Scanning range for the selected channel frequency table

Scan Type

The scan type can be selected with a popup menu. For ATSC the default choice is the "Full Scan".

Full Scan 

With this option a list of frequencies on which multiplexes can be found is scanned. The list of frequencies can vary because each country can decide which part of the spectrum is available for broadcast.
Now, pressing the right arrow key shows three fields with configuration data.

  • Frequency Table
    The selection "Broadcast" is to be used for OTA programming. For cable signals there are various options; note that the "High" options only scan the high part of the range. This goes quicker but possibly not all channels are found.
  • Modulation
    For OTA antenna signals "Terrestrial (8-VSB)" is the correct choice. For cable signals it does depend on your cable provider but QAM-256 is used often as it gives the highest bitrate per multiplex.
  • Scanning Range
    This allows you to reduce the range of the channels to be scanned. This does reduce the scanning time but it can result in missing channels. If you can receive the same channels from different transmitters then a full scan will result in duplicate channels. In that case the scanning range can be reduced so that only the desired channels are found.


After the parameters have been selected press the left arrow key to go back to the Channel Scan page. The Full Scan takes a lot of time because it tries all possible frequencies but it is the only way to find all channels if you start with a clean slate. When the list of transport stream multiplexes is complete, it is much faster to do a "Scan of all existing transports".

Channel Editor

Configuring the capture cards and the video sources is usually done only once. To view the result of the initial channel scan and to do channel scans later the Channel Editor is used. This is option 6 on the mythtv-setup main menu.

  • Main menu of mythtv-setup

  • All channels of all video sources sorted by Channel Number

Channel List

The Channel List shows for each channel from left to right the channel number, the channel name, the service ID, the frequency, the transport ID and the video source name. The frequency is shown in Hz except for satellite; then the frequency is shown in kHz followed by a H or a V for horizontal or vertical polarity.
Navigation in the Channel Editor is a bit more complicated than in the previous pages. When in the channel list, the up/down arrow keys navigate through the list. The right arrow key brings you to the next field, the "Sort Mode" selection; the left arrow key brings you back to the channel list. Navigating in this page is easier if you keep in mind that for the software all fields are a single list of menu items; down is the next item and up the previous item. The difference is that some menu items are now arranged horizontally instead of in a single column like on most pages.
Pressing the space bar on a selected channel gives the next menu page. This is described a bit later after the options on the current page are described.

Sort Mode

The Sort Mode is selected with the right arrow key for the next choice and the left arrow key for the previous choice. With the up arrow key, or, when at the first item, also the left arrow key, you get back to the channel list. With the down arrow key, or, when at the last item, also the right arrow key, you get to the Video Source selection. It is possible to sort on "Channel Number", "Channel Name", "Service ID", "Frequency", "Transport ID" or "Video Source". The channel list is immediately updated when the Sort Mode selection is changed.

  • All channels of all video sources sorted by Channel Name

  • All channels of all video sources sorted by Service ID

  • All channels of all video sources sorted by Frequency

  • All channels of all video sources sorted by Transport ID

  • All channels of all video sources sorted by Video Source name

The sort mode "Frequency" is especially useful for scans of satellites; this makes it easy to compare the mythtv-setup scan results with the channel information on www.lyngsat.com.

Video Source

The Video Source is selected with the arrow keys in the same way as the Sort Mode. In addition to the real video sources there is the first choice "All" which selects the channels of all video sources together. The last choice, after the real video souces, is "(Unassigned)" and this shows the channels that do not have a video source. This list should be empty and if it is not then there is something wrong.
The Channel List is immediately updated when the Video Source selection is changed.

Delete

The Delete button gives you the option to delete all channels of the selected video source. Currently the transports (multiplexes) of the video source are not deleted, only the channels.

The deleted channels are not immediately removed from the database but only marked for deletion; the actual removal from the database is done later in a housekeeping process when there are no recordings anymore from the deleted channels. This means that recordings will keep the channel information even if the channel is deleted.

After a channel scan all channels that can be received will be present again; however, all channel information that is not automatically obtained in the scan but that has been manually added, such as the values of the "visible", "xmltvid" and "iconpath" fields, will be lost.

The values of these fields can be recovered from the deleted channels by using the Restore Data function described below.

Note that the values for "callsign" and "channel number" are automatically obtained in the scan. However, on a rescan these values will not be updated. This means that these values can be changed with the Channel Editor and that these changes are permanent. Of course, this also means that if the provider changes the callsign or the channel number this change will be ignored on a rescan.

To summarize:

  • If you want to keep the current channel numbers and callsigns then do not delete the channels and only do a channel scan.
  • If you want to have the channel numbers and the callsigns the way they are now broadcast then first delete all the channels and then do a channel scan, optionally doing the Restore Data afterwards.

Hide channels without a channel number

All channels get a channel number in the scan. If there are channels that do not have a channel number then this is manually configured or there is possibly something wrong. Since version 32 this option also hides the channels that are set invisible (Not Visible or Never Visible) in the Channel Editor (see [[1]]).

Channel Scan

This button brings you to the Channel Scan page described earlier.

Restore Data

When all channels are deleted and a new scan is done then the XMLTV ID, the Visible status and the icon filename path have a default value because these values are not part of what is received with a channel scan.

This button brings you to a page where you can restore these fields for all channels in the currently selected video source. The data is obtained from a search in all deleted channels. This means that it is possible delete all channels, do a channel scan and then retrieve the XMLTV ID, the Visible status and the icon filename path from the channels that were just deleted.

This feature is possible because a channel that is deleted is not immediately deleted but only marked for deletion; the actual deletion is done later in a housekeeping process. This then means that one should not wait before restoring the data; once the channels are really deleted the data can not be restored anymore.

Icon Download

This button starts a download command from a website that has channel icons such as lyngsat.com. This only works sometimes. When it does work you get a list of channel icons to choose from; the icon file is stored in $HOME/.mythtv/channels and the name of the icon file is stored in the database. The name of the icon file can be viewed and modified in the Icon field of the Channel Options in the Channel Editor.

Edit Transports

This button brings you to the Transport Editor page, which is described after the Edit Channel paragraph.

Edit Channel

Pressing the space bar on a selected channel in the channel list gives the next menu page.

  • Select channel to edit and press Space

  • Select Common or Filters

The choice is between Common and Filters. The choice for Filters allows selection of filters to be applied when playing back recordings from this channel. Maybe this still works, or maybe not, but it is not documented here.
Select "Common".

  • Channel options - part 1

  • Select value for Visible

Channel Name

This is the channel name as received during the channel scan.

Channel Number

The channel number can be received during the channel scan when there are Logical Channel Numbers in the received data and when there is a Logical Channel Number for the channel. If there is no Logical Channel Number then the service ID is used as the channel number. If that number is already in use then another string is generated to uniquely identify the channel within the video source. Note that the channel number is not necessarily a number. The channel number can be changed to create your own channel ordering, although care must be taken that channel numbers are unique otherwise the channel presentation in the program guide of mythfrontend becomes a mess.

Freq/Channel

This is the VHF or UHF channel number that identifies the frequency of the signal. This dates back from the days of analog television received with an antenna. This field is only filled when the channel is found in a "Full Scan" search over all channels which can be done with DVB-T/T2. If you delete all channels and do a scan of all transports then this field is left empty. It is in mythtv-setup also possible to do a "Full Scan" with DVB-C but the frequencies on cable networks are usually different from the frequencies of the VHF and UHF channels.
This field is not used anymore in mythtv.

Callsign

The callsign is used in North America to uniquely identify a channel with a short string, e.g. WSYX or KPRC or something like that. In Europe there is usually no callsign and then this field is filled with the channel name. Notably the program guide in MythTV expects short callsign strings and this can be a reason to edit this field to something short. For example, channel "Eurosport 2 HD" can be shortened to "EuSp2".
The callsign is not changed anymore when doing a rescan so a value once entered will not be overwritten. However, if you delete a channel and then find that channel again in the next scan then the previously entered values are lost.
Note that the callsign is used in the MythTV scheduler to identify each channel. This means that if you change a callsign, all recording rules defined for that channel need to be updated also.

Visible

If the value is set to Always Visible or Visible the channel will be visible in the EPG. Set the value to Always Visible or Never Visible to prevent MythTV and other utilities such as MythUtil-Channel-HDHR-visibilityCheck from automatically managing the value for this channel. The default value is Visible. This option is not changed when doing a rescan.

Service ID

The service ID identifies the channel in the transport stream multiplex. The service ID is usually unique within a network. On a single satellite there can be channels from more than one network so if you scan all channels on a satellite it is possible to get duplicate service IDs. If the service ID is changed it will point to another channel or to no channel at all. This value should never need to be changed.

  • Channel options - part 2

Transport ID

The transport ID identifies a transport stream multiplex in a network. This value is shown here for information only, it cannot be changed.

Frequency

This is the frequency of the transport stream multiplex. The value is shown here for information only. It is possible to change the frequency in the Transport Editor page and then it is changed for all channels in that multiplex.

Video Source

This shows the video source of this channel. The value can be changed but it changes only the value in table transport and not anywhere else, so the results will be unpredictable. The video source is also stored in table dtv_multiplex which suggests it should be editable in the Transport Editor but this is not possible.

TV Format

This is something from the analog days. It is not used in digital television.

Priority

The priority is used for scheduling. Positive values increase the scheduling priority and make this a preferred channel compared to other channels that can receive the same program. Negative values are possible and reduce the scheduling priority but some versions of the SQL database are reported to have problems with negative priority values.
The default value is 0.

  • Channel options - part 3

Use on air guide

When this option is checked the guide data in the EIT (event information table) will be used for this channel. EIT data collection must be configured for the video source so at least one capture card of the video source must have EIT enabled. See Use_DVB_card_for_active_EIT_scan.

XMLTV ID

XMLTV is the name of a system which obtains and processes program guide information. This field contains the identification to match the MythTV channel to the same channel in the XMLTV files. The ID can be entered manually but it can also be filled automatically depending on where the XMLTV data comes from. Read XMLTV for more information on tools to help automate obtaining the ID.
The value of this field is preserved when a new channel scan is done.
The field is greyed-out and cannot be selected when, in the Video Source configuration, field "Listings Grabber" is set to "Transmitted Guide Only (EIT)".

DataDirect Time Offset

Offset (in minutes) to apply to the program guide data during import. This can be used when the listings for a particular channel are in a different time zone.

Commercial Detection Method

The default value is "Use Global Setting" but it is possible to select a commercial detection method for each channel individually. This can be used to disable commercial detection for channels that do not have commercials. It is also possible to select a method of commercial detection that works well with that particular channel.

Icon

Image file to use as the icon for this channel on various MythTV displays. This field has only the name of the file itself; all icons are located in $HOME/.mythtv/channels. There is an Icon Download button in the Channel Editor page which can download channel icons and which then also puts the file name of the selected icon in this field. This feature however only works sometimes.
The value of this field is preserved when a new channel scan is done.

Transport Editor

This page shows all the transports of the selected video source. Pressing the space on a transport shows a page with details about that transport. The values can be changed but this is seldom necessary.
There is the possibility to add a transport manually.
It is only possible to edit transports if there is a capture card connected to the selected video source.

  • Transport Editor for video source Ziggo

  • Transport at 474Mhz of video source Ziggo

Video Source

This is a read-only field that shows the video source of all the transports in the list.

(New Transport)

Selecting this creates a new transport called New Transport (without the brackets) which is added at the bottom of the list of transports. When creating a new transport at least the fields Frequency, Symbol Rate and Modulation must have correct values.

Digital TV Standard

In a DVB country the choices are DVB and MPEG; in an ATSC country the choices are ATSC, OpenCable and MPEG.

Frequency (Hz)

Frequency of the multiplex in Hz (for DVB-C/T/T2) or in kHz (for DVB-S/S2).

Symbol Rate

Number of symbols per second. For DVB-C this is a number like 6900000 (6.9 million). For DVB-S/S2 the number of symbols per second is much higher, somewhere around 27500000 (27.5 million). If this number is not known it is not possible to demodulate the received signal.

Modulation

Some tuners can figure this out by themselves; for these tuner an automatic choice, such as QAM Auto for DVB-C, is possible. For some tuners the exact value is needed, e.g. QAM-256; this will work on all tuners. If the video source is used by more than one type of tuner it is possible that one tuner understands QAM Auto while the other does not.

Scanning with HDHomeRun tuners

HDHomeRun tuners are network tuners that connect via Ethernet to a MythTV backend. They have one Ethernet connector and usually one antenna (coaxial) input connector. Inside are two or four tuners. For Europe there are versions for DVB-T/T2, DVB-C or a combination of both. Similar devices are for sale in the USA for unencrypted ATSC, both for OTA and for ClearQAM/cable.

The HDHomeRun Prime USA CableCard tuners are completely different and how to use them is described in page Silicondust_HDHomeRun_Prime.

The tuners can be used from everywhere in the network; there is a procedure to allocate a tuner on-demand and to release it later when not needed anymore. MythTV uses on-demand allocation since version 30. This does assume that all tuners in one HDHomeRun device are identical and are connected to the same RF input, which is the case for all recent HDHomeRun devices. Older HDHomeRun devices with two RF inputs, such as the HDHR-US, are still supported but the two RF inputs need to be connected to the same signal.

The HDHomeRun tuners for DVB-C and DVB-T/T2 are used in the same way as conventional DVB-C and DVB-T/T2 tuners. The HDHomeRun devices can do their own channel scans but that functionality is not used in MythtTV. However, this can be useful to verify that the HDHomeRun works correct when investigating configuration problems. To do this, put the IP address of your HDHomeRun in the browser and follow the menu.

HDHomeRun tuners may need larger timeouts than the default.

Creating the Capture Cards

For each of the tuners in one HDHomeRun box that will be used in MythTV one capture card needs to be created.

  • Select capture card type HDHomeRun

  • Select HDHomeRun device on the network

To use all tuners of a four-channel HDHR3-DVBC device in MythTV the procedure in mythtv-setup is:

  • Select "Capture cards"
  • Select "(New capture card)" ; this generates an entry "New capture card" at the bottom of the list
  • Select the ¨New capture card" entry at the bottom of the list
  • Select "HDHomeRun networked tuner"
  • Press the right arrow key
  • Tick box "Use HDHomeRun 1410F45C (hdhomerun3_dvbc 10.0.0.171)"
  • Press Escape
  • In popup box, select "Save then Exit¨

This has now created one capturecard entry for one tuner on the hdhomerun on 10.0.0.171.

Now comes the key point.
You have to perform the above sequence for each of the HDHomeRun tuners that you want to use in MythTV.
To use four tuners, you have to do this four times.

If you have more than one identical HDHomeRun device connected to the same video source/antenna cable, you can configure each capture card to use a tuner on any of the HDHomeRun devices by ticking the boxes for all. This can be useful when there are also other clients on the network that use the HDHomeRun devices. There is the possibility to make configuration mistakes; be careful to combine only similar HDHomeRun devices, so only DVB-C with other DVB-C and DVB-T/T2 with other DVB-T/T2 HDHomeRun devices.

Input Connection

Just like for a conventional tuner card there must be an Input Connection defined between the capture card and the video source. This must be done for each capture card of the HDHomeRun and the capture cards should all be connected to the same video source.

  • Select capture card type HDHomeRun

  • Select video source for the HDHomeRun

It is possible to select any existing video source. In this example the HDHomeRun is a DVB-C device that is connected to the same cable as the other DVB-C tuners. The HDHomeRun is therefore connected to the same video source so that it shares the channel list. It is not necessary to do a new channel scan if a scan has already been done with the other tuner.

When there is more than one capture card then you can select which capture card you want to use for the scan. By default the first one is selected but here the HDHomeRun is the second one so we chose that one. The scan parameter setting for a HDHomeRun DVB-C device is exactly the same as for any other DVB-C card, as described earlier.

  • Select HDHomeRun capture card for DVB-C scan

  • Result of the DVB-C scan with the HDHomeRun

After the scanning is complete the popup window shows that the HDHomeRun has found all existing channels again. It is a good idea to do a channel scan with a new capture card to make sure that your new card does work as expected.

For DVB-C it is always possible to use one video source for all tuners connected to the same RF signal cable (except for VBox tuners). However, when using a MythTV version before 32 there can be a problem for DVB-T/T2. The HDHomeRun DVB-T/T2 tuners do automatically tune to whatever the modulation system is and hence all transports are marked as DVB-T after a channel scan with the HDHomeRun. This is a problem when the same video source is also used with other DVB-T/T2 tuners for whom this does make a difference such as the MyGica T230 USB tuner. In that case, do the channel scan with the other tuner or use separate video sources.
This is fixed since version 32.

EIT program guide information

It is possible to select for any HDHomeRun tuner the "Use HDHomeRun for active EIT scan" option but only the first tuner can be used to receive the EIT program guide information. Also passive EIT scanning is only possible on the first tuner. This can be considered to be either a bug or a feature.
Given that there is only one RF input on a HDHomeRun which is used for all tuners, all tuners do receive the same signal and all tuners should be connected to the same video source. Each video source does need only one tuner to receive EIT program guide information; this is then available for all tuners connected to that video source. On the other hand, using more than one tuner for EIT on one video source will usually result in a faster buildup of the program guide at the expense of more system load.
The reason for this behavior is that the HDHomeRun identification, an 8-character string such as 1410F45C, is used for all tuners of that HDHomeRun. For EIT scanning the result is that all tuners except the first are seen as virtual tuners which can never be used for active EIT scanning since virtual tuners cannot be tuned individually.
It is not difficult to change the software to allow active EIT scanning on each tuner. This can be done by using unique tuner identifiers, for instance by appending the HDHomeRun string with the major ID.

Multirec

The "Schedule as Group" option, which can be selected for DVB (/dev/dvb/*/*) and SatIP tuners, is always selected for HDHomeRun tuners. This means that when needed additional virtual tuners are created on demand. It is not possible to disable this other than by direct database manipulation. See also Max Recordings and Schedule as Group.

Scanning with VBox tuners

VBox is a network tuner, which has to be setup prior to adding to mythtv, refer to the user manual appropriate to the type of VBox device see https://vboxcomm.com/support/guides/vbox-tv-gateway/

Once the VBox has been setup, add it to mythtv see https://www.mythtv.org/wiki/VBox

A VBox for DVB-C cannot share a video source with another type of DVB-C tuner such as a HDHomeRun or a USB tuner. The DVB-C tuners of one VBox, or from more VBoxes, can and should share the same video source.

EIT is not supported on VBox tuners so Schedules Direct or another source of program guide information is needed.


Scanning with Sat>IP tuners

SAT>IP is a protocol and IP-based architecture for receiving and distributing satellite signals (see [1], [2] and [3] for more details). Depending on manufacturer and device not just only DVB-S/S2 but DVB-T/T2 and DVB-C may be supported as well.

Sat>IP boxes are hardware devices that have a satellite tuner for two or four inputs and that can be connected to a MythTV backend via the network, conceptually similar to the HDHomeRun devices.

There exists also an open-source Sat>IP server implementation, minisatip (see [4]), that runs on Linux. With this software a local DVB tuner can be made available on the network. The minisatip software supports not only satellite tuners but also DVB-C and DVB-T/T2 tuners.

As of version 32, MythTV has native support for devices that use the Sat>IP protocol. The Sat>IP devices can be used in the same way as DVB (/dev/dvb/...) devices and they do support channel scanning, Multirec and receiving EIT program guide information when that is present.

Before version 32 the Sat>IP boxes could only be used with the HTTP protocol and M3U playlists. This is described in page SAT2IP_players_as_capture_cards. Using Sat>IP servers in this way is of course still possible.


Note: To get perfect recordings without missed packets a large UDP buffer is needed. At startup mythbackend tries to configure the UDP buffer size to 8 Mbyte and if this fails the following message is given: 

       RTP UDP socket receive buffer size set to 212992 but requested 8000000
       To prevent UDP packet loss increase net.core.rmem_max e.g. with this command:
       sudo sysctl -w net.core.rmem_max=8000000
       and restart mythbackend.

The need for this huge buffer is caused by the current implementation where the RTP data is read on a thread that is shared with other backend activities instead of on a separate thread. If and when this is fixed a buffer size of 1 Mbyte is needed, similar to what is used by the HDHomeRun devices.

External links

[1] https://en.wikipedia.org/wiki/Sat-IP
[2] http://www.satip.info/benefits-satip-technology
[3] https://www.satip.info/sites/satip/files/resource/satip_specification_version_1_2_2.pdf
[4] https://github.com/catalinii/minisatip

Using Unicable DVB-S/S2 tuners

This paragraph contains some notes about using Unicable. This is strictly speaking not channel scanning but it can be useful information to get a Unicable system working.

Power supply

With some tuner cards the Unicable system does not work reliably. Symptoms are: timeouts during channel scans, visual artifacts during playback and a non-zero value of the continuity_error_count of recordings. The same tuner card connected to the legacy (non-Unicable) input of the same LNB usually works OK.

A DVB-S/S2 tuner card supplies the DC power to the LNB. For legacy (the "Universal Europe") LNBs the DC voltage level is switched between 13V and 18V to signal the polarity. In the original Unicable specification EN50494 it states that the DC voltage level should be low; while sending the tuning command with DiSEqC the DC voltage level should be high and afterwards it should be low again.
This is exactly how it is implemented in MythTV, but it looks like the low DC voltage is not enough to power the Unicable II LNBs.
One of the manufacturers of Unicable II LNBs also sells the "Unicable II Power Inserter 5 - 2400MHz" (see Inverto). This device puts always 17V DC on the cable and this is reported to fix the problem.
Tuner cards that are reported to work without a Power Inserter are:
- DVBSky S952 v3
Tuner cards that do NOT work are:
- DVBSky S950-C
- Digital Devices Cine S2 V6.5

The Digital Devices card in combination with a Selfsat H50dCSS Unicable 2 flat satellite antenna does work when a Power Inserter is used.
The DVBSky S950-C card in combination with a Unicable II LNB works with an experimental version of MythTV in which the DC voltage is always put at the high value of 18V.
Probably all cards will work when the Power Inserter is used.

Satellite splitter

In a Unicable system there is only one cable connected to the LNB. To connect this to multiple tuners a satellite splitter is needed. A satellite splitter is similar to a conventional splitter that is used for terrestrial and cable but with the following differences:

  • Frequency range 5-2400MHz

Conventional splitters have a frequency range of up to 900MHz. Satellite signals use frequencies up to 2400MHz.

  • DC power pass

Satellite tuner cards supply the DC power for the LNB. With multiple tuners each tuner must be able to supply the power to the LNB and to send DiSEqC commands and therefore the satellite splitters do have a "Power Pass" feature that allows DC power and DiSEqC commands to go from the tuner card to the LNB but not to the other tuner cards.

Help, it does not work...

There is always a lot of output in the terminal window where mythtv-setup is started. For instance, there is a list of the updated channels which looks like this: 

Updated old channels (79):
qam_256:120000000:Film1 On Demand.:105:5555:1536:19657:2073=2073:dvb
qam_256:160000000:Ketnet:53:5555:1536:19025:2054=2054:dvb
qam_256:160000000:SBS6:930:5555:1536:19027:2054=2054:dvb
qam_256:176000000:Ziggo TV HD:13:5555:1536:19327:2069=2069:dvb
qam_256:444000000:Studio 040:36:5555:1536:19842:3005=3005:dvb
qam_256:444000000:Avulo:37:5555:1536:19843:3005=3005:dvb

If mythtv-setup is started like this: 

mythtv-setup -v chanscan

then a lot of additional information is printed, such as the raw channel list before filtering and the channels that are discarded.

If mythtv-setup is started like this: 

mythtv-setup -v chanscan --loglevel=debug

then you get almost as much information as you would find in a stream analyzer such as DVB Inspector.

If it really does not work then there is the MythTV forum and the mailing list where you can get help: 

mythtv-users@mythtv.org
http://lists.mythtv.org/mailman/listinfo/mythtv-users
http://wiki.mythtv.org/Mailing_List_etiquette
MythTV Forums: https://forum.mythtv.org

If there is a problem that is not a configuration issue but a real bug then you can have a look at the issue list on Github 

https://github.com/MythTV/mythtv/issues

and if the problem is not shown there then please create a new issue.

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