Channel Scanning

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Version:
31
This HOWTO is for MythTV Version 31. For previous versions this guide can also be used but there are then less options available.

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 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 to the previous menu level.

In lists you can usually 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.

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 last menu page then you can 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.

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.

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

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.

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 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 7000ms.

Tuning timeout (ms)

Leave this at the default value. If there are problems with channels not being found this value can be increased to 10000ms. For non-encrypted channels this is always long enough. Some TV cards with a Conditional Access Module (CAM) and a smartcard may need more time, up to 20 seconds.

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.

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

Skip this.

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.

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 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). Other options are available when they have been configured elsewhere.

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 is 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.

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 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. Skip this if you want to do a channel scan.

Starting channel

This is the channel that is tuned to when Live 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. It is always possible to go to the program guide, select a program on the channel that you want, press Enter and choose "Watch This channel".

Interactions between inputs

Skip this for now. Wonderful features can be configured here but they are not needed for a channel scan.

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.


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. For instance, the people in the UK probably want BBC1 on channel number 1. 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.

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.
  • Full Scan (Tuned)
    This is the default choice for DVB-C and DVB-S/S2. Pressing the right arrow shows a page in which the modulation parameters, needed to tune to the first multiplex, have to be specified. 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 will not find the other multiplexes.
  • Import existing scan
    <TBD>
  • 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 far less frequent. Especially 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.

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:

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 multiplex on two different frequencies. There is no functionality in MythTV to figure out if multiplexes are duplicates and which one is then to be used and which one is to be deleted. MythTV just stores all multiplexes and all received channels which means that the channel list will have duplicates.

The best way is probably to figure out from other sources which transmitter and which frequencies are the best to be used in your region. With the Transport Editor a transport can be deleted (by pressing the key "D") and when a transport is deleted the channels from that transport are also deleted. Probably some of the remaining channels will now not have correct channel numbers. This can be fixed manually with the Channel Editor but it is also possible to delete all channels and then do a "Full scan of all existing transports". This will create the correct channel list.
Note that 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.

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 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.

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.

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

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. Only old capture cards support only DVB-S.

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:

LNB 

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

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 

<TBD>

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.

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


4. Video sources

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.

DVB-S2 Full Scan (Tuned)

The pictures show the scanning parameters for Astra-2 on 28.2E. Which frequency is used as initial frequency is not very important; at least for the four Western European satellites tested any frequency is good.

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.

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


Configuration in mythtv-setup:

  • 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


  • 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


  • Create four video sources; one for each LNB.
- For LNB 1 video source Hotbird 13E0 with scan frequency 12188000
- 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 Scan

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.

Channel List

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 Name", "Channel Number" or "Multiplex Frequency". The channel list is immediately updated when the Sort Mode selection is changed.

The sort mode "Multiplex Frequency" is 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. This is generally not a good idea. Note that the transports (multiplexes) of the video source are not deleted, so it is relatively easy to do a rescan and get all channels back. However, if you do this, all channel information that is not automatically obtained in the scan but that has been manually added, such as "visible", "xmltvid" and "iconpath", is lost.
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.

Hide channels without a channel number

All channels should have a channel number. If there are channels that do not have a channel number then there is something wrong. This option might be removed in the future.

Channel Scan

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

Icon Download

This button does NOT work. It tries to download icons from lyngsat.com but this fails. This option might be removed in the future.

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.

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 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.

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.

Use on air guide

When this option is checked the guide data in the EIT (event information table) will be used for this channel.

XMLTV ID

<TBD>

DataDirect Time Offset

<TBD>

Commercial Detection Method

<TBD>

Icon

<TBD>

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.

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. If the exact value is known, e.g. QAM-256, this is a better choice. The scan always fills in the exact value.


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. For the USA there are versions for ATSC and for CableCard.

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 does support on-demand allocation since version 30.

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.


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.

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"
  • 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.

Input Connection

Just like for a conventional tuner card there must be an Input Connection defined between the capture card and the video source.

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.

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.

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

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 please create a ticket on

https://code.mythtv.org/trac/wiki