[mythtv-users] MythArchive has been added to svn - Please test

[Cory Papenfuss]

>> Looks very promising. I especially like that it can handle MPEG4s as
>> well. I would like to try it this weekend.
>> Some questions:
>> - Can it reduce the size of recordings, if they are too large ? Does
>> it use mythtranscode or tcrequant for that ?
>> - Is the new archive format playable ? (Currently I archive with the
>> nuv+sql option from nuvexport which is playable on both Linux and
>> Windows. But that method breaks when the database structure change...)
>> - I guess the conversion takes place in the background, like with
>> mythburn. Can you confirm that ?
>>
>> Best regards
>> Niels Dybdahl
>
>
> I notice a heavy reliance on ffmpeg - doesn't this suffer from the same
> A/V desync issues as every other non-ProjectX DVD creation method when
> using a cutlist?

WARNING:  I haven't tried the SVN but just speaking from what I've played 
with in the past regarding A/V sync.  I could be completely full of sh*t.

 	FFMPEG isn't fundamentally the problem... it can play the streams 
captured from ivtv properly.  Where the real problem comes in is when the 
streams are demuxed into audio and video streams... that demux from a PS 
into ES's is where sync information is lost.  Consider that mplayer has 
never had sync issues playing captures.

 	That said, with the non-lossless mythtranscode, exporting 
MPEG2->MPEG2 with a *reencode* didn't have sync issues either.  Most 
things know how to *play* an mpeg with varying sync, so that's why it 
worked fine.  Similarly to an export to/from MPEG4... it requires a 
reencode so the sync should be preserved in the decode->reencode process.

 	The new lossless MPEG2 cutting fixes the streams in the process of 
cutting them.  I don't remember exactly how Geoffrey did it, but I think 
the end result is a stream that has continuous, non-varying timestamps 
between the audio and video... maybe with dummy packets to fill in holes? 
I don't recall exactly.  In any event, they can be demuxed/remuxed (or 
replex'd in place to add the DVD-NAV stream to the PS necessary for 
authoring) without losing sync.

 	Exciting times for mythtv are afoot...

-Cory


-- 

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* Cory Papenfuss, Ph.D., PPSEL-IA                                       *
* Electrical Engineering                                                *
* Virginia Polytechnic Institute and State University                   *
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