[mythtv] [PATCH] DVB fixes

Augusto Cardoso augusto at carhil.net
Sat Dec 20 21:01:42 EST 2003


Hi!

Correction, the transform.c and .h patches are related to channel changing and adjusting the header accordingly. It shouldn't affect multiple cards because each card will run it's own channel thread.

	Augusto

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On 12/20/2003 at 5:50 PM Augusto Cardoso wrote:

>Hi!
>
>
>
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>
>On 12/21/2003 at 2:21 AM Kenneth Aafløy wrote:
>
>>Hi!
>>
>>> What is your configuration? DVB card? Do you use anything 
>>> other than mythtvfrontend to play the video?
>>> Can you send me a sample or make it available .nuv file?
>>> Even better, can you get a .nuv and also save some raw TS 
>>> stream, including all PIDs but NULL packets. You can do this 
>>> using the test_dvr(linuxtv.org) and using the PID 0x2000. 
>>> I'll be glad to look at this and figure what's wrong.
>>
>>My setup is a Hauppauge Nexus-S with a Conax CAM.
>>
>>And my recordings start with a 1e0 start code, which is video,
>>and probably not the start of a keyframe, since the output is
>>garbled at the start.
>>
>
>It's not possible to get a 1e0 with the new code. Are you sure the patch
>applied clean to all files? I'll make sure I sent correct patch.
>The .nuv file should start with a 00 00 01 BA. What PIDs are you using? v,
>a anything else?
>
>>> You can try to enable the wait_for_seqstart, however, the 
>>> code in dvbrecorder.cpp has to be revised in order for the 
>>> "wait_for_seqstart" to work properly.
>>> The issue with the current code is that it drops the Program 
>>> Stream Header. The current decoder in mythtv works without 
>>> the start code, but a number of other applications don't like 
>>> a PS file without this, because they identify the file as a 
>>> PES and depending on the application do bad things...
>>
>>Strange tho, since my recording does not start with that header.
>>
>>What is the startcode of that header (I'll test waiting for that)?
>>
>
>The header doesn't come in the TS. It has to be generated. It's generated
>in ctools.c in libdvbdev.
>I had a couple of other people testing this before I send the patch and in
>100% of the tests the file start with the proper header 00 00 01 BA. I've
>been testing it for one week now.
> 
>>> The transform.c should wait for the start code, it works for 
>>> all the tests I've done using Satellite. DVB-T should be the same.
>>
>>Hmm, it didn't do that when I wrote it, did you put that feature in
>>with your patch (which was the reason for putting in the wait stuff)?
>>
>
>In order to generate the header 00 00 01 BA, it's necessary to have the
>video and audio stream info. This is done automatic in transform.c. The
>code that uses the wait_for_seqstart removes the header by accident. The
>patch in transform.c is to fix the problem with multiple cards.
>
>I'm very puzzled with your results. If the wait_for_seqstart is false, you
>have one 'v' pid and one 'a' pid, you should never get a 00 00 01 E0 as
>the first code 4 bytes in the .nuv file. This is wrong for a PS file.
>
>	Augusto
>
>
>
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