[mythtv-users] Re: Getting good audio sync in nuvexport/transcodings w/cutlist?

Cory Papenfuss papenfuss at juneau.me.vt.edu
Thu Jun 2 19:20:44 UTC 2005

On Thu, 2 Jun 2005, Brad Templeton wrote:

> On Thu, Jun 02, 2005 at 10:59:19AM +0200, belcampo wrote:
>> Try opening the file in avidemux directly and save it, one thin I got was:
>> **saving:**
>> Last frame is a B frame, choosing better candidate
>> Trying :130348
>> Taking previous frame as last frame 130349
>>  Avi family
>> TS: no ts sync word
> Well, I did try editing the file in avidemux2, using its own cut point
> system to get rid of the unwanted stuff.   It didn't die, but it produced
> a file with audio slowly going out of sync, until it was out by a large
> margin by the end -- up to a second.
> I expected this could happen because avidemux reported that it had a sound
> sync error of 0.5 seconds after loading the file.
> So I suspect that even if I get nuvexport to call avidemux with success,
> I will not get a usable file in any event, and am giving up on this for
> the meantime.
> Note that Myth's player and other players do not have a sound sync problem
> on the original file, and I was able to transcode the original file
> (with not cuts) using mencoder without sound problems (though my
> experiments at reverse telecine with pullup resulted in dropped frames
> in some, but not all locations in the film.  Rather odd.)
> So for now I'm stuck until I find another editor, the only choice being
> to transcode to mp4 in mencoder to save some space, but with no cuts.

 	I haven't been following this specific thread, but it's a 
shortcoming that I"ve been interested in and monitoring for a good long 
while now (>12 months).  In case you haven't tried yet, you might want to 
try "encapsulating" the MPEG2 into an AVI with mencoder.  Something like 
'mencoder -ovc copy -oac copy -o out.avi in.mpg' or whatever... search the 
archives for my name and mencoder.  Someone else suggested this and it was 
a partial workaround... complete with avidemux rebuiling B-frames, etc.

 	Also, ProjectX seemed initially very exciting as an editor for 
maintaining sync.  I tried it a month or so ago and it seemed to 
work where others were broken.  Recently there's been some noise on the 
list about how it's got issues too, but I haven't had time to look into 


* Cory Papenfuss                                                        *
* Electrical Engineering candidate Ph.D. graduate student               *
* Virginia Polytechnic Institute and State University                   *

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