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This page is up-to-date to MythTV version 0.20
What is DVB?
(Digital Video Broadcasting) is the most popular standard for digital TV. Other standards include ATSC, and Digicipher II (DCII). DVB is also the name of the Linux drivers used for most DTV receivers in Linux, including ATSC, DCII and other MPEG-2 and MPEG-4 based broadcast standards.
DVB was initially based on the MPEG-2 compression and packet formats, but has recently been extended to support MPEG-4 AVC/H.264 streams as well. The physical part comes in three variants:
- Terrestrial (over-the-air with an antenna) (DVB-T)
- Cable (DVB-C)
- Satellite (DVB-S)
Some channels (especially pay channels) are encrypted. There's a standardized decryption hardware slot called "Common Interface" (CI) for the decryption hardware called "Conditional Access Module" (CAM), which usually also needs a smartcard for authorization and accounting.
CI+ or Common Interface Plus
CI+ or Common Interface Plus is a specification that extends the Common Interface (DVB-CI) as found in the digital broadcasting standard DVB. It has been developed by consumer electronic firms Panasonic, Philips, Samsung and Sony, as well as pay-TV technology company SmarDTV and fabless chip maker NEOTION.
A first draft of the specification has been put up for review early in 2008. CI+ implements a form of copy protection between a Conditional Access Module (CAM) and the digital television receiver (DTV).
By making use of certificates and a certification authority, a trusted channel is formed between the CAM and DTV, when scrambled content is being received. In the original CI standard, decrypted content could be sent over the PCMCIA interface unscrambled.
DVB is widely used in Europe and Asia, over-the-air (DVB-T), via cable (DVB-C) and via satellite (DVB-S). There are hundreds of DVB-S channels available in Europe on the satellite fleets of Astra and Eutelsat, almost all of them "free to air" (unencrypted), including all the major free stations. DVB-C is also widely used in european cable tv networks, with different modulation schemes and also including HDTV. DVB-T is being deployed at the moment in UK, Germany, France, Australia, Spain, Netherlands, Denmark, Sweden and other countries as a replacement for the classic analog TV over antenna.
In the US, Dish Network uses standard DVB (with Nagravision 2 encryption), while DirecTV uses an earlier, incompatible system that predates DVB, sometimes called DBS (Digital Broadcast Satellite). In Canada, StarChoice uses DCII and Bell ExpressVu uses standard DVB. Most of what's available via FTA in North America is religious programming, or programming not intended for mass consumption. Still, many hobbyists enjoy receiving FTA broadcasts, and a PC with a DVB card is one of the best ways to receive these broadcasts.
Cable operators in the US were supposed to move to ATSC for by 2006 for broadcast channels but few have complied with the law. Most major TV stations in the US are now transmitting a digital signal in ATSC in addition to their analog signal. This can be received with a conventional TV antenna and an appropriate decoder, including several ATSC cards supported by MythTV.
For DVB devices supported by linux see the following pages on the linuxtv.org wiki.
- DVB-C (Cable) - [http://www.linuxtv.org/wiki/index.php/DVB-C_Devices
- DVB-S (Satellite) - http://www.linuxtv.org/wiki/index.php/DVB-S_Devices
- DVB-T (Terrestrial) - http://www.linuxtv.org/wiki/index.php/DVB-T_Devices
Some of the 'standard' ways of doing things may be subtly different for DVB users, this can be particularly confusing for people getting started with DVB. Some things of note:
- People mention getting cards with 'hardware MPEG2 encoders' to reduce the CPU load. This doesn't apply for DVB as it is digital (ie, already getting an MPEG stream)
- Transcoding profiles are a little different/nonsensical for DVB (I believe this has been changed as of 0.19/0.20).
- Recording profiles are not so useful - no longer able to change bitrate or framesize
You can test whether DVB is working on your Linux machine (before installing MythTV) using the Dvb-apps software suite.
DVB in MythTV
- Tuner cards that work
- LinuxTV DVB support - The DVB layer of Mythtv with list of supported hardware
- Dvb-apps - usefull tools when working with DVB
- Example DVB-S MythTV Setup - Useful information when using DVB-T and DVB-S.
- http://linuxtv.org/wiki - The linuxtv.org DVB Wiki (These guys created the dvb-apps tools)!
- http://www.acaciaclose.co.uk - MythTV 0.18/0.19 DVB on SUSE 9.3/10.0 setup guide
- http://www.ethics-gradient.net/myth/mythdvb.html - Martin Smiths DVB-T Setup Guide
- http://www.mythbox.co.uk - MythTV and PVR setup guide for DVB-T in the UK
- http://www.dvbstreamexplorer.com - An MPEG-2/DVB Transport Stream Analyzer for Windows
- Some utilities/sample code aimed at using radio recordings from DVB with iTunes / iPod / Podcasts