Difference between revisions of "Testing your DVB device"

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This page provides a few suggestions on how to test that a DVB card installed on your system is functioning properlyIt won't tell you how to install the specific hardware that you have (see [[How to install DVB device drivers]] for some generic instructions). Nor does this page describe the use of feature rich viewing software. But it will describe to you some steps on the command line that are indispensable for quick setup and viewing with DVB hardware.
+
This page provides a few suggestions on how to test that a properly installed DVB device <sup>'''1'''</sup> is functioning correctlyThe command line steps described are also indispensable for quick setup and no frills viewing with DVB hardware under Linux.
 +
 
 +
{{Note|<sup>'''1'''</sup> In other words, this article assumes that you have already both:
 +
:* physically installed the device into, or attached it to, your system (refer to the manufacturer's instructions for such details) and
 +
:* installed the drivers for your hardware and have the proper modules loaded (see "[[How to Obtain, Build and Install V4L-DVB Device Drivers]]" for such details)<br>
 +
:Having completed such tasks, you should at least now have a ''/dev/dvb/adapter0/'' directory. (If you have additional DVB devices installed in your system, they will be assigned an increased ''adapter'' number accordingly).}}<br>
 +
 
 +
== Comparison of DTV testing applications ==
 +
 
 +
The following table lists the main features of the different command line DTV testing utilities. For specific information on usage, have a look at its specific wiki article.
 +
<br>
 +
 
 +
{| border=1 cellpadding=10 cellspacing=0 valign="top"
 +
|- bgcolor=#efefef valign="top"
 +
|'''feature \ utility'''
 +
|'''dvb-apps [[zap]]'''
 +
|'''[[Szap-s2]]'''
 +
|'''[[dvbtune]]''' and '''[[dvbstream]]''' from dvbtools
 +
|'''[[dvbsnoop]]'''
 +
|-
 +
|'''download'''
 +
|[http://linuxtv.org/hg/dvb-apps linuxtv.org/hg/dvb-apps]
 +
|[http://mercurial.intuxication.org/hg/szap-s2 http://mercurial.intuxication.org/hg/szap-s2]
 +
|[http://sourceforge.net/projects/dvbtools http://sourceforge.net/projects/dvbtools]
 +
|[http://dvbsnoop.sourceforge.net http://dvbsnoop.sourceforge.net]
 +
|-
 +
|'''supported delivery systems'''
 +
|DVB-S, DVB-C, DVB-T, ATSC
 +
|DVB-S, DVB-S2
 +
|DVB-S, DVB-C, DVB-T
 +
|DVB-S, DVB-C, DVB-T
 +
|-
 +
|'''comments'''
 +
|useful for debugging, but inappropriate for newer delivery systems.
 +
|satellite only.
 +
|outdated.
 +
|outdated, but still the most powerful tool for reading and parsing DVB tables. Hint: use another tool to tune and dvbsnoop in parallel to read data. Unfortunally, dvbsnoop misses support for newer descriptors.
 +
|-
 +
|'''supported features'''
 +
|
 +
* channel scan for legacy systems
 +
* tuning
 +
* streaming
 +
* show signal strength/lock
 +
|
 +
* tuning
 +
|
 +
* tuning (dvbtune)
 +
* streaming (dvbstream)
 +
|
 +
* analyse DVB tables and MPEG streams
 +
* show signal strength/lock
 +
|}
 +
 
  
Again, '''this article assumes that you have already physically installed the device into your system, and have also installed the driver for your  hardware and have the proper modules loaded''' i.e. you should at least have a ''/dev/dvb/adapter0/'' directory. Additional DVB devices installed on your system will be assigned an increased ''adapter'' number accordingly.
 
  
 
== Using dvb-apps ==
 
== Using dvb-apps ==
  
 
'''1. Obtain the dvb-apps package'''<BR>
 
'''1. Obtain the dvb-apps package'''<BR>
The [[LinuxTV dvb-apps]] have many useful tools with great functionality.  
+
See the [[LinuxTV dvb-apps]] article for details on how to obtain the package.  The dvb-apps package contains several useful tools.  
  
 
'''2. Scan for the channels you can receive''' <BR>  
 
'''2. Scan for the channels you can receive''' <BR>  
The program from the [[LinuxTV dvb-apps]] that we will use for this step is [[Scan|scan]].  
+
Refer to the [[Scan|(dvb)scan]] article for details of how to perform this step. Once familiar with the content of that article, you will recognize that this step can be summarized (in general form) by: 
 +
mkdir ~/.''{a,c,s,t}''zap
 +
(dvb)scan /''path_to_the_initial_scan_file'' > ~/.''{a,c,s,t}''zap/channels.conf
  
 +
Note that you may have both a program <code>scan</code> and <code>dvbscan</code> installed on your system, and only one of them may work.
  
'''3. Tune a frequncy and program'''<BR>
+
'''3. Tune a frequency and program'''<BR>
Use the command [[tzap]] for [[DVB-T]], [[czap]] for [[DVB-C]], [[szap]] for [[DVB-S]] and [[azap]] with [[ATSC]].
+
Refer to the [[Zap|zap]] article for details of how to perform this step. Once familiar with the content of that article, you will recognize that this step can be summarized (in general form) by: 
 +
$ /usr/bin/''{a,c,s,t}''zap  -r -c ~/.''{a,c,s,t}''zap/channels.conf "''channel name''"
 +
where, respective to the type of transmission, [[azap]] is used for [[ATSC]], [[czap]] for [[DVB-C]], [[szap]] for [[DVB-S]] and [[tzap]] for [[DVB-T]].  
 +
Make sure you do not overlook the -r option for setting up the /dev/dvb/adapterX/dvr0 interface. Otherwise, you cannot record data from dvr0.
  
As an example, to automatically tune both channel and [[PID|PIDs]] for video and audio to the channel called "KPAX-DT" produced in the ATSC scan output above, run:
+
{{Note|If (dvb)scan was unable to correctly resolve the audio or video [[PID]] values for a channel in the previous step, a manual adjustment to the channels.conf file will be necessary to correct any inaccurately written PID(s) information.  Such occurrences tend to be rare, but nonetheless, they do happen -- often, one only becomes aware of a problem with the PID values after unsuccessful attempts to tune a particular channel.   The correct values may be determined using using [[dvbtraffic]] (see step '''4.c)''' below). Another method for finding correct PID values for a channel is also outlined in the section entitled "[[Scan#A_word_about_dvbscan_and_audio_streams|A word about dvbscan and audio streams]]".}}
  $ /usr/bin/azap  -r -c ~/.azap/channels.conf "KPAX-DT"
+
    
+
The output of that azap command would be something like:
+
  using '/dev/dvb/adapter0/frontend0' and '/dev/dvb/adapter0/demux0'
+
  tuning to 177028615 Hz
+
  video pid 0x0031, audio pid 0x0034
+
  status 00 | signal edc0 | snr a122 | ber 00000000 | unc 000000ff |
+
  status 1f | signal 0000 | snr ff28 | ber 00000000 | unc 00000000 | FE_HAS_LOCK
+
    ...(repeated updated output) ...
+
Note: The output will continue to update endlessly, but you can terminate it with Ctrl C
+
  
Not all the numbers are implemented in some drivers, but good is signal > 8000, status 1f (all bits set), snr (Signal to Noise Ratio) should be > 8000, ber (bit error rate)  - low is good, unc (Uncorrectable blocks) - low is good.
 
  
Then you can try to tune in one of the channels:
+
'''4. After you've tuned a frequency and program'''<BR>
  
 +
'''a)''' You could now start up your simple TV watching application and decode the stream you have tuned.
  
  $ /usr/bin/czap  -r -c ~/.czap/channels.conf "ZTV Norway"
+
For example, while keeping ''{a,c,s,t}''zap running in the first console shell, open up another console and run
which in turn displays lines similar to (terminate with Ctrl-C)
+
mplayer /dev/dvb/adapter0/dvr0 <options>
 +
If you have more than one dvb device installed in your system, then you will have to pass the correct ''adaptor'' number.  See the [[MPlayer#Usage_with_more_complex_DVB_device_configurations|MPlayer article]] for some further information, as well as the MPlayer man page (i.e. in a console run "man mplayer") for a lengthy list of options.
  
  using '/dev/dvb/adapter0/frontend0' and '/dev/dvb/adapter0/demux0'
 
  tuning to 177028615 Hz
 
  status 1f | signal 0000 | snr ff28 | ber 00000000 | unc 00000000 | FE_HAS_LOCK
 
  ... (repeated output) ...
 
  
 +
'''b)''' Or, you could now start up a datastreamer 
  
'''4. After you've tuned a frequency and program'''<BR>
 
 
You could now start up your TV watching application or datastreamer. 
 
  
Or, alternatively, you may want to see some statistics of what's coming in for each channel and PID.
+
'''c)'''  Or, alternatively, you may want to see some statistics of what's coming in for each channel and PID.
 
Example:  
 
Example:  
   dvbtraffic
+
   $ /usr/bin/dvbtraffic  
And finally
+
  dvbdata
+
  
Then for some statistics,  try
+
dvbtraffic which will access the [[Device nodes and character devices#DVB character devices|/dev/dvb/adapter0/dvr0 logical device]].
  $ /usr/bin/dvbtraffic
+
An example of output from dvbtraffic is:
  
 +
0000    24 p/s    4 kb/s    37 kbit
 +
0010    20 p/s    3 kb/s    31 kbit
 +
0011    20 p/s    3 kb/s    31 kbit
 +
0012    70 p/s    12 kb/s  106 kbit
 +
0015    1 p/s    0 kb/s    2 kbit
 +
0080    26 p/s    4 kb/s    40 kbit
 +
0082    26 p/s    4 kb/s    40 kbit
 +
0087    25 p/s    4 kb/s    38 kbit
 +
0100    25 p/s    4 kb/s    38 kbit
 +
0101    25 p/s    4 kb/s    38 kbit
 +
0102    24 p/s    4 kb/s    37 kbit
 +
<span style="color:#ff0000">0200</span>  8567 p/s  1572 kb/s 12885 kbit  <span style="color:#ff0000"> <--- </span>
 +
0201  4708 p/s  864 kb/s  7081 kbit
 +
0205  926 p/s  170 kb/s  1392 kbit
 +
0240    49 p/s    8 kb/s    75 kbit
 +
0241    49 p/s    8 kb/s    75 kbit
 +
<span style="color:#ff0000">028b</span>  261 p/s    47 kb/s  393 kbit  <span style="color:#ff0000"> <--- </span>
 +
0294  174 p/s    31 kb/s  262 kbit
 +
0295  130 p/s    23 kb/s  196 kbit
 +
02bc    75 p/s    13 kb/s  113 kbit
 +
1fff    87 p/s    15 kb/s  131 kbit
 +
2000 15329 p/s  2814 kb/s 23055 kbit
 +
-PID--FREQ-----BANDWIDTH-BANDWIDTH-
  
== First steps using dvbsnoop ==
+
In this case, for the frequency that has been tuned, PID 0x0200 is for the video stream of an HDTV channel and PID 0x028b is for the associated audio stream (both of these have been highlighted in red in the above output for easier visual identification). These PID values presented by dvbtraffuc are in hexadecimal form and need to be converted to their decimal representation (respectively, 512 and 651) for use in a channel.conf file.<BR>
As an alternative, [[dvbsnoop]] is a small, down-to-earth util. As it's very hardware-near, it's very handy for debugging and seeing what's going on with the card (tuning works? data coming in? signal strong enough?). (On the other side, if all in the section above works fine, you can jump over this section here.)
+
Install it, e.g. with debian:
+
  # apt-get install dvbsnoop
+
Apparently, dvbsnoop isn't in any of the usual Fedora repositories at this time (Feb 2007).  Instead, download a copy directly from the source forge site using steps similar to the following.  Note this is for version 1.40.  Your download URL (and the extracted directory ''dvbsnoop-bin-i386-1.4.00-api3'') will change as succeeding versions of dvbsnoop are published on Source Forge. Also you may wish to copy the binary ''dvbsnoop'' out to a more convenient directory in your path, rather than the deeply buried directory ''~/dvbsnoop/dvbsnoop-bin-i386-1.4.00-api3/bin-i386-api3'' which, in this example, contains the binary. Then ''./dvbsnoop'' will not be required,  just ''dvbsnoop'' as shown in the debian example below.
+
  $ mkdir ~/dvbsnoop
+
  $ cd dvbsnoop
+
  $ wget  http://downloads.sourceforge.net/dvbsnoop/dvbsnoop-bin-i386-1.4.00-api3.tar.gz?modtime=1124046233&big_mirror=0
+
  $ tar xvzf *.tar.gz
+
  $ ls
+
  $ cd dvbsnoop-bin-i386-1.4.00-api3
+
  $ ls
+
  $ cd bin-i386-api3
+
  $ ls
+
  $ ./dvbsnoop -help
+
  $ ./dvbsnoop -s pidscan
+
  
Then try things like
+
This is the line you would create in the file "channel.conf" given the PID values from the dvbtraffic output shown above:
 +
 
 +
Nine High Def Gold Coast:746625000:INVERSION_AUTO:BANDWIDTH_7_MHZ:FEC_3_4:FEC_3_4:QAM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_16:HIERARCHY_NONE:<span style="color:#ff0000">512</span>:<span style="color:#ff0000">651</span>:1138
 +
 
 +
And finally
 +
  dvbdate
 +
 
 +
== Using dvbsnoop ==
 +
If the testing steps in the dvb-apps section above work fine, you can jump over this section here. On the other hand, [[dvbsnoop]] is a small, down-to-earth utility that is very handy for debugging and also seeing what is occuring with a dvb device (i.e. tuning works? data coming in? signal strong enough?).
 +
 
 +
'''1. Obtain the dvbsnoop package'''<BR>
 +
See the [[dvbsnoop]] article for details on how to obtain the package.
 +
 
 +
'''2. Testing with dvbsnoop'''<BR>
 +
Try things like
 
   dvbsnoop -help
 
   dvbsnoop -help
 
   dvbsnoop -s pidscan
 
   dvbsnoop -s pidscan
Line 80: Line 143:
 
The latter will spit out a lot of hexdumps - at least you receive '''something''' ;-)
 
The latter will spit out a lot of hexdumps - at least you receive '''something''' ;-)
  
== Save a TV program to harddisk with dvbstream ==
+
== Save a TV program to your hard drive ==
The handy thing about digital TV is, it comes in as a digital stream that you can save right away to your harddisk without any changes necessary to it. Therefore, hardly any CPU resources are needed -- just a lot of HD space (few GB per hour as the stream is MPEG-2 which is not as compressed as for example DivX/MPEG-4). A good program that can do that (and more) is [[dvbstream]].  
+
The handy thing about digital TV is, it comes in as a digital stream that you can save right away to your harddisk without any changes necessary to it. Therefore, hardly any CPU resources are needed -- just a lot of HD space (few GB per hour as the stream is MPEG-2 which is not as compressed as, for example, DivX/MPEG-4; it's even more as mostly one [[transport stream]] contains multiple [[PID]]s). There are several ways to do this.  For example:
 +
 
 +
'''a) Using the combination of {a,c,s,t}zap and cat'ing the logical dvr device to save a program stream to disk''' <BR>
 +
If you have a channel tuned with {a,c,s,t}zap (and note that you MUST also be using the -r parameter to set up the logical dvr device in order for the following to work; see [[Zap]] for detail), open up another shell console and run (as root user):
 +
cat /dev/dvb/adapter0/dvr0 > <filename>
 +
The result is that particular program stream will be written to disk, and you should be able to play it back at any later time with your favourite media player.  
 +
 
 +
'''b) Using the combination of {a,c,s,t}zap and test_dvr to save an entire transport stream to disk'''
 +
 
  
Install it, e.g. with debian:  
+
'''c) Saving to disk with dvbstream''' <BR>
   # apt-get install dvbstream
+
[[dvbstream]] is a useful program that, amongst other things, can save a DVB stream to disk.
 +
'''Method 1''': First tune into a channel, as described above in the zapping step, and then next have dvbstream save a particular stream to file. For example:  
 +
   tzap 'BBC ONE'
 +
  dvbstream 600 601 -o > bbc1.mpeg
 +
The values "600 and 601" are, respectively, the video and audio [[PID]]s for the channel BBC ONE, as derived from the channels.conf file.  So this is why it's important that you have your personal channels.conf file with all the PIDs so you can look them up.
  
Let's tune into a channel with tzap as described above, and then you can just save the stream into a file like this:
+
'''Method 2''': Alternatively, instead of using a combination of *zap and dvbstream, you can use dvbstream alone provided you pass which frequency to tune and list the correct PIDs.  For example:
  tzap BBC ONE
+
  dvbstream 600 601 -o >BBC1.mpeg
+
So this is why it's important that you have your personal channels.conf file with all the PIDs so you can look them up. Instead of using tzap you can do it all in one - tune the frequency and select the right PIDs:
+
 
   dvbstream -f 578000 600 601 -o >bbc1.mpeg
 
   dvbstream -f 578000 600 601 -o >bbc1.mpeg
  
Wait a few seconds and then press Ctrl+C to stop. You can open the MPEG file with players that play movie files (decode MPEG2), like Mplayer, (g)xine or noatune.  
+
Wait a few seconds and then press Ctrl+C to stop. You should then be able to open/playback the recorded file with any of your favourite media players (like Mplayer, (g)xine, noatune, etc. etc ) provided you have the correct decoders installed on your system (which, in general regards to DVB transmissions, are usually going to be MPEG-2, but can now also be MPEG-4).  
  
 
If the file is rather small, e.g. smaller than 1 MB after a minute of recording, then you can't receive this TV channel - maybe the reception is bad (too weak antenna signal) - or maybe your card's frequency is not tuned for the right sender? Watch out, some PIDs come up a few times (but for different frequencies).  
 
If the file is rather small, e.g. smaller than 1 MB after a minute of recording, then you can't receive this TV channel - maybe the reception is bad (too weak antenna signal) - or maybe your card's frequency is not tuned for the right sender? Watch out, some PIDs come up a few times (but for different frequencies).  
  
This might not be what you wanna do every day (unless you only watch BBC1 or you can easily memorise all your channels with their two PIDs) - but it's very fast and easy to do these steps, e.g. for a test.
+
This might not be what you wanna do every day (unless you only watch BBC1 or you can easily memorise all your channels with their two PIDs) - but it's very fast and easy to do these steps for testing purposes.
  
 +
==Next steps - More feature rich viewing software ==
 +
It is not the intention of this page to provide a detailed description of the use of DVB hardware with more complex Linux viewing software applications.    Suffice it to say that you will have some choice.  For example:
 +
* for light TV watching with a DVB device under Linux, [[MPlayer]], [[Xine]], [[Kaffeine]], [[Klear]] and a few others are often selected. 
 +
* alternatively, for "Media Center" type applications, the usual first suspects are [[Freevo]], [[MythTV]], and [[VDR]], but there are others as well
 +
* you could use the streaming facilities of [[dvbstream]], [[Mumudvb]], dvblast, etc... and then watch the MPEG-2 stream (even possible on a different computer) with programs like Xine, MPlayer etc. 
  
==More Software - next steps ==
+
For some further inspiration on what's possible with more advanced software usage see:
You have a lot of choice. [[MPlayer]], [[Xine]], [[Kaffeine]] , [[Klear]] are probably the first choices selected for light TV watching with a DVB card.
+
* the [[TV Related Software]] page, a commented software list, and
 +
* [[Example setups]]
  
Alternatively, you could use [[dvbstream]] and then watch the MPEG-2 stream (even possible on a different computer) with programs like Xine, MPlayer etc.
 
  
For "Media Center" type applications, the usual first suspects are [[Freevo]], [[MythTV]], and [[VDR]] (note: you'll need to install the [[VDR Software Decoder Plugin]] if you want to use VDR for watching with a software decoding card). 
+
---------
  
 +
(note: you'll need to install the [[VDR Software Decoder Plugin]] if you want to use VDR for watching with a software decoding card). 
  
== Also See ==
 
* [[Example setups]] for inspiration on what's possible with more advanced software usage
 
* [[Commented software list]]
 
 
* Digital Video Broadcasting – A practical guide by Hugo Mills [http://www.carfax.org.uk/docs/DVB/]
 
* Digital Video Broadcasting – A practical guide by Hugo Mills [http://www.carfax.org.uk/docs/DVB/]
 +
[[Category:Drivers]]
 +
[[Category:Software]]

Latest revision as of 20:08, 2 July 2013

This page provides a few suggestions on how to test that a properly installed DVB device 1 is functioning correctly. The command line steps described are also indispensable for quick setup and no frills viewing with DVB hardware under Linux.

Note: 1 In other words, this article assumes that you have already both:
  • physically installed the device into, or attached it to, your system (refer to the manufacturer's instructions for such details) and
  • installed the drivers for your hardware and have the proper modules loaded (see "How to Obtain, Build and Install V4L-DVB Device Drivers" for such details)
Having completed such tasks, you should at least now have a /dev/dvb/adapter0/ directory. (If you have additional DVB devices installed in your system, they will be assigned an increased adapter number accordingly).

Comparison of DTV testing applications

The following table lists the main features of the different command line DTV testing utilities. For specific information on usage, have a look at its specific wiki article.

feature \ utility dvb-apps zap Szap-s2 dvbtune and dvbstream from dvbtools dvbsnoop
download linuxtv.org/hg/dvb-apps http://mercurial.intuxication.org/hg/szap-s2 http://sourceforge.net/projects/dvbtools http://dvbsnoop.sourceforge.net
supported delivery systems DVB-S, DVB-C, DVB-T, ATSC DVB-S, DVB-S2 DVB-S, DVB-C, DVB-T DVB-S, DVB-C, DVB-T
comments useful for debugging, but inappropriate for newer delivery systems. satellite only. outdated. outdated, but still the most powerful tool for reading and parsing DVB tables. Hint: use another tool to tune and dvbsnoop in parallel to read data. Unfortunally, dvbsnoop misses support for newer descriptors.
supported features
  • channel scan for legacy systems
  • tuning
  • streaming
  • show signal strength/lock
  • tuning
  • tuning (dvbtune)
  • streaming (dvbstream)
  • analyse DVB tables and MPEG streams
  • show signal strength/lock


Using dvb-apps

1. Obtain the dvb-apps package
See the LinuxTV dvb-apps article for details on how to obtain the package. The dvb-apps package contains several useful tools.

2. Scan for the channels you can receive
Refer to the (dvb)scan article for details of how to perform this step. Once familiar with the content of that article, you will recognize that this step can be summarized (in general form) by:

mkdir ~/.{a,c,s,t}zap
(dvb)scan /path_to_the_initial_scan_file > ~/.{a,c,s,t}zap/channels.conf

Note that you may have both a program scan and dvbscan installed on your system, and only one of them may work.

3. Tune a frequency and program
Refer to the zap article for details of how to perform this step. Once familiar with the content of that article, you will recognize that this step can be summarized (in general form) by:

$ /usr/bin/{a,c,s,t}zap  -r -c ~/.{a,c,s,t}zap/channels.conf "channel name"

where, respective to the type of transmission, azap is used for ATSC, czap for DVB-C, szap for DVB-S and tzap for DVB-T. Make sure you do not overlook the -r option for setting up the /dev/dvb/adapterX/dvr0 interface. Otherwise, you cannot record data from dvr0.

Note: If (dvb)scan was unable to correctly resolve the audio or video PID values for a channel in the previous step, a manual adjustment to the channels.conf file will be necessary to correct any inaccurately written PID(s) information. Such occurrences tend to be rare, but nonetheless, they do happen -- often, one only becomes aware of a problem with the PID values after unsuccessful attempts to tune a particular channel. The correct values may be determined using using dvbtraffic (see step 4.c) below). Another method for finding correct PID values for a channel is also outlined in the section entitled "A word about dvbscan and audio streams".


4. After you've tuned a frequency and program

a) You could now start up your simple TV watching application and decode the stream you have tuned.

For example, while keeping {a,c,s,t}zap running in the first console shell, open up another console and run

mplayer /dev/dvb/adapter0/dvr0 <options>

If you have more than one dvb device installed in your system, then you will have to pass the correct adaptor number. See the MPlayer article for some further information, as well as the MPlayer man page (i.e. in a console run "man mplayer") for a lengthy list of options.


b) Or, you could now start up a datastreamer


c) Or, alternatively, you may want to see some statistics of what's coming in for each channel and PID. Example:

 $ /usr/bin/dvbtraffic 

dvbtraffic which will access the /dev/dvb/adapter0/dvr0 logical device. An example of output from dvbtraffic is:

0000    24 p/s     4 kb/s    37 kbit
0010    20 p/s     3 kb/s    31 kbit
0011    20 p/s     3 kb/s    31 kbit
0012    70 p/s    12 kb/s   106 kbit
0015     1 p/s     0 kb/s     2 kbit
0080    26 p/s     4 kb/s    40 kbit
0082    26 p/s     4 kb/s    40 kbit
0087    25 p/s     4 kb/s    38 kbit
0100    25 p/s     4 kb/s    38 kbit
0101    25 p/s     4 kb/s    38 kbit
0102    24 p/s     4 kb/s    37 kbit
0200  8567 p/s  1572 kb/s 12885 kbit    <--- 
0201  4708 p/s   864 kb/s  7081 kbit
0205   926 p/s   170 kb/s  1392 kbit
0240    49 p/s     8 kb/s    75 kbit
0241    49 p/s     8 kb/s    75 kbit
028b   261 p/s    47 kb/s   393 kbit    <--- 
0294   174 p/s    31 kb/s   262 kbit
0295   130 p/s    23 kb/s   196 kbit
02bc    75 p/s    13 kb/s   113 kbit
1fff    87 p/s    15 kb/s   131 kbit
2000 15329 p/s  2814 kb/s 23055 kbit
-PID--FREQ-----BANDWIDTH-BANDWIDTH-

In this case, for the frequency that has been tuned, PID 0x0200 is for the video stream of an HDTV channel and PID 0x028b is for the associated audio stream (both of these have been highlighted in red in the above output for easier visual identification). These PID values presented by dvbtraffuc are in hexadecimal form and need to be converted to their decimal representation (respectively, 512 and 651) for use in a channel.conf file.

This is the line you would create in the file "channel.conf" given the PID values from the dvbtraffic output shown above:

Nine High Def Gold Coast:746625000:INVERSION_AUTO:BANDWIDTH_7_MHZ:FEC_3_4:FEC_3_4:QAM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_16:HIERARCHY_NONE:512:651:1138

And finally

 dvbdate

Using dvbsnoop

If the testing steps in the dvb-apps section above work fine, you can jump over this section here. On the other hand, dvbsnoop is a small, down-to-earth utility that is very handy for debugging and also seeing what is occuring with a dvb device (i.e. tuning works? data coming in? signal strong enough?).

1. Obtain the dvbsnoop package
See the dvbsnoop article for details on how to obtain the package.

2. Testing with dvbsnoop
Try things like

 dvbsnoop -help
 dvbsnoop -s pidscan

This will give out a lot of numbers, but if you understand the system of DVB you should see if they make sense. Go for one of the PIDs (choose a right one which is a bit difficult as you don't know what they stand for unless you used the scan line above) and try:

 dvbsnoop -s bandwidth <PID>
 dvbsnoop <PID>

The latter will spit out a lot of hexdumps - at least you receive something ;-)

Save a TV program to your hard drive

The handy thing about digital TV is, it comes in as a digital stream that you can save right away to your harddisk without any changes necessary to it. Therefore, hardly any CPU resources are needed -- just a lot of HD space (few GB per hour as the stream is MPEG-2 which is not as compressed as, for example, DivX/MPEG-4; it's even more as mostly one transport stream contains multiple PIDs). There are several ways to do this. For example:

a) Using the combination of {a,c,s,t}zap and cat'ing the logical dvr device to save a program stream to disk
If you have a channel tuned with {a,c,s,t}zap (and note that you MUST also be using the -r parameter to set up the logical dvr device in order for the following to work; see Zap for detail), open up another shell console and run (as root user):

cat /dev/dvb/adapter0/dvr0 > <filename> 

The result is that particular program stream will be written to disk, and you should be able to play it back at any later time with your favourite media player.

b) Using the combination of {a,c,s,t}zap and test_dvr to save an entire transport stream to disk


c) Saving to disk with dvbstream
dvbstream is a useful program that, amongst other things, can save a DVB stream to disk. Method 1: First tune into a channel, as described above in the zapping step, and then next have dvbstream save a particular stream to file. For example:

 tzap 'BBC ONE'
 dvbstream 600 601 -o > bbc1.mpeg

The values "600 and 601" are, respectively, the video and audio PIDs for the channel BBC ONE, as derived from the channels.conf file. So this is why it's important that you have your personal channels.conf file with all the PIDs so you can look them up.

Method 2: Alternatively, instead of using a combination of *zap and dvbstream, you can use dvbstream alone provided you pass which frequency to tune and list the correct PIDs. For example:

 dvbstream -f 578000 600 601 -o >bbc1.mpeg

Wait a few seconds and then press Ctrl+C to stop. You should then be able to open/playback the recorded file with any of your favourite media players (like Mplayer, (g)xine, noatune, etc. etc ) provided you have the correct decoders installed on your system (which, in general regards to DVB transmissions, are usually going to be MPEG-2, but can now also be MPEG-4).

If the file is rather small, e.g. smaller than 1 MB after a minute of recording, then you can't receive this TV channel - maybe the reception is bad (too weak antenna signal) - or maybe your card's frequency is not tuned for the right sender? Watch out, some PIDs come up a few times (but for different frequencies).

This might not be what you wanna do every day (unless you only watch BBC1 or you can easily memorise all your channels with their two PIDs) - but it's very fast and easy to do these steps for testing purposes.

Next steps - More feature rich viewing software

It is not the intention of this page to provide a detailed description of the use of DVB hardware with more complex Linux viewing software applications. Suffice it to say that you will have some choice. For example:

  • for light TV watching with a DVB device under Linux, MPlayer, Xine, Kaffeine, Klear and a few others are often selected.
  • alternatively, for "Media Center" type applications, the usual first suspects are Freevo, MythTV, and VDR, but there are others as well
  • you could use the streaming facilities of dvbstream, Mumudvb, dvblast, etc... and then watch the MPEG-2 stream (even possible on a different computer) with programs like Xine, MPlayer etc.

For some further inspiration on what's possible with more advanced software usage see:



(note: you'll need to install the VDR Software Decoder Plugin if you want to use VDR for watching with a software decoding card).

  • Digital Video Broadcasting – A practical guide by Hugo Mills [1]