[mythtv-users] Audio Sync when exporting to DVD using Nuvexport

Len Reed lreed at levanta.com
Tue Jan 4 14:26:34 EST 2005


Sync has always been a problem for me on exported files.  I've got a 
PVR-250, I'm in in US (so NTSC), FC3 installed using Jarod Wilson's 
instructions from http://wilsonet.com/mythtv/fcmyth.php (thanks!).  I 
uninstalled all the myth*.rpms that apg-get got and built mythtv from 
the latest CVS source, built kernel 2.6.10 from http://www.kernel.org, 
and used ivtv-0.2.0-rc3c (from C. Kennedy, thanks).

I did all this over the weekend, building the system from the metal up. 
  Audio sync is still bad (audio starts out nearly synced but gets 
progressively further behind as the video is played).  It was that way 
on previous systems, too; this problem's not new.

But...
1. audio sync is fine when watching via MythTV.
2. audio sync is fine if I copy the original *.nuv to any Linux system 
and watch using mplayer.

#2 is curious, since it means that there must be enough sync information 
in the .nuv file alone for mplayer to get the sync right.  Anything else 
(transcode, avidemux2, etc.) has the sync drift problem.

Len


Lane Schwartz wrote:
> On Tue, 4 Jan 2005 12:03:56 -0600, Lane Schwartz <dowobeha at gmail.com> wrote:
> 
>>On Mon, 03 Jan 2005 16:31:26 +0000, Gary Dawes
>><garydawes at blueyonder.co.uk> wrote:
>>
>>>Having finally treat myself to a DVD burner for christmas, I have
>>>started exporting shows to DVD, but have found that the audio is ahead
>>>of the video by a small amount.
>>>
>>>I have searched the various wikis, and mailing lists, and have found
>>>various posts about this, but while different people have suggested
>>>different things, none of them have worked for me, and noone else with
>>>the problem has reported that they have solved the problem, and by what
>>>method.
>>>
>>>I'm running knoppmyth, with mythtv 0.16, and the latest versions of
>>>transcode mjpegtools available from apt. I'm also running the latest
>>>nuvexport (27/12).
>>>
>>>I've checked my audio recording settings and they are at 48khz
>>>
>>>I found one snippit of information which suggested running mpeg2desc -m
>>>on the .mpg file to determine the audio offset, and then using that
>>>information to reencode the file.
>>>
>>>Any ideas?
>>>
>>>Thanks
>>>
>>>Gary
>>
>>
>>Gary,
>>
>>I've had this issue, too. In fact you probably ran across some of my
>>earlier posts in your research.
>>
>>The only conclusion that I was able to come to is that there is a bug
>>in some ivtv versions which cause the mpeg files that are recorded to
>>have some flaw in them. I was always able to play the original
>>recordings with no sync issues. It was when I tried the mpg2->mpg2
>>cutting that I hit problems. I also hit the same problems with a
>>manual edit using avidemux and mplex.
>>
>>After spending a good chunk of my Christmas vacation on it, I now have
>>a fully functional Myth box again. I can successfully export
>>recordings with no audio sync issues.
>>
>>While I was debugging, I tried almost everything. I tried multiple
>>versions of avidemux, mjpegtools, even multiple versions of the
>>kernel. I tried ivtv 0.1.9 and 0.1.10 (100zz, I think). I tried FC2,
>>then back to FC1. Nothing worked.
>>
>>Why does it work now? Well, I switched back to FC2. Then I used one of
>>the new 0.2 ivtv drivers. I think that's what did it. I can now
>>successfully export my _new_ recordings.
>>
>>However, when I try to export any of the old recordings, I still get
>>audio sync issues. This fact makes me even more confident that the
>>problem lies in the ivtv driver.
>>
>>I know this is a really frustrating problem. Try the new ivtv drivers
>>and see if that helps. I think they're in atrpms testing, so make sure
>>that's enabled (this is assuming you're running Fedora and using apt).
>>
>>If you'd like I can get you the versions of all of the relevant
>>programs on my functional box.
>>
>>Cheers,
>>Lane
>>
> 
> 
> I should point out that I'm using a PVR-250 and am in the U.S. 
> 
> Lane
> 
> 
> 
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-- 
Len Reed
lreed at levanta.com
Levanta: Lowering the real costs of Enterprise Linux


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