[vdr] FF card A/V sync suggestion

Chad Flynt hoochster at sofnet.com
Sat Oct 21 20:05:45 CEST 2006

I will chime in again and also state this has nothing to do with 1 
particular channel.  This, at least in North America, happens no matter 
what channel it is on.  I can't recall any live TV ever being affected, 
but every recording I have has desync issues if I play straight through 
VDR on a FF card, some worse than others mind you, but every one gets 
out of sync.  I don't know if it is an NTSC thing or what.  I am willing 
to accept that if it is, but the problem still stands.  But it sounds as 
if it happens on PAL systems as well from all those that have chimed 
in.  I am in no way ungrateful for everything VDR has done and all the 
development from others, but this problem has been brought up many times 
in the past and ends up getting dropped as mentioned.  Mainly, obviously 
due to the fact the developers can't reproduce it.  But it isn't just 
Mplayer that plays fine, Xine plays fine as well.  Both of these 
outputting via the FF Card.  So, not just going full software mode.  So 
that's 2 different playback devices that bypass whatever bugs or whatnot 
you might be mentioning.  It is only when playing back through whatever 
VDR is using.  It may very well be passing it straight through and the 
others aren't.  But that is what we are trying to find out.  And find 
out if there is a way that we can have an option if anything to choose 
playback a different way.  I am not a programmer, so I don't know the 
ins or outs of how this can be accomplished, but being as so many others 
are now complaining about it, there has to be some way of figuring this 
out.  Thanks for any insight you have on looking into this problem.

Pasi Juppo wrote:

>Udo Richter wrote:
>>C.Y.M wrote:
>>>If the answer to this question could be discovered, then problem
>>>solved.  So,
>>>what you are suggesting is VDR is not doing something that mplayer is
>>>doing that
>>>fixes the problem.  Hmmmmmm... so then it is not a driver or firmware
>>>after all?? Could we agree that much? :) 
>>I wouldn't go that far. For this concrete case, since it is limited to
>>one specific channel, there's a good chance that the encoding of the
>>channel breaks some standards limitation.
>>There's also most likely nothing wrong on VDR, as VDR is basically just
>>forwarding data streams. If mplayer does a better job, then its probably
>>more like a bug workaround.
>>Generally, things would be a lot better if the driver/firmware would do
>>A/V resyncing constantly and not just at playback start. That way, A/V
>>desync wouldn't built up, and desync would only happen for a short time.
>How come you make the conclusion that this is limited to one specific
>channel? To my understanding there are multiple channels where this
>problem occurs.
>The best to start solving this problem is to try to figure out what
>happens with the recordings that are correct but still cause desync
>problems. This has been suggested already by many readers. Since it
>seems that only few people have access to the firmware source code the
>debugging is quite limited..
>Br, Pasi
>vdr mailing list
>vdr at linuxtv.org

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