[libdv-dev] Re: audio distortion with dvavi

[Bradley R. <b_r...@ya...>]

A few days ago I was complaining about audio distortion that I was
experiencing in converting my videos to DV.  I'm trying to play videos
on my tv by -

  1.  using MPlayer's mencoder to convert the movie to AVI-type-2 DV;
  2.  using dvavi to convert the AVI to a 'raw dv' file;
  3.  using dvconnect to transfer it down a 1394 interface to my
      camcorder, and thence to the tv.

Drew Perttula was kind enough to help me out on this.  The only reason
I haven't written back to the list is because I've been tied up trying
to examine my next problem (!) in detail before reporting back.

Drew said that the distortion was due to my DV having audio encoded at
44100Hz, and suggested 48000Hz was a better rate.  Sure enough, I told
mencoder to resample (using the '-srate 48000' option) and the distortion
went away totally.  Thank you Drew!  I appreciate your time in checking
out my example file, and I'm sorry I didn't get back to you before now.

However Roman Shaposhnick has just now said:

> > Audio sample rate for DV is 48KHz or 32KHz. 
> 
>   Not true. 44.1KHz is entirely legal in a generic sense. 
>   It might not be supported by your particular camcorder, though.

My camcorder is a Sony TRV-17E (PAL) and, like Drew, I found audio
distortion at 44100Hz but everything was fine at 48000Hz.

My problem now is that I've got drastically bad synchronisation (well,
no sync!) between audio and video.  The AVI-type-2 file produced by
MPlayer's mencoder is fine; when I use mplayer to play that file the video
and audio are in perfect sync.  But after the second step - using dvavi
to produce a raw digital video file - the audio drags *badly* behind
the video - like 20 or 30 seconds behind after a minute or two.  Again
using mplayer to play the raw-dv file.  Double-checked by observing while
downloading the file via dvconnect to the camcorder.

It seems to me to be a clear case of dvavi messing up, but I was going
to work on more examples before posting my plea for help.  Given
Roman's post, however, I thought I'd send off a quick comment now.

In summary - my camcorder, also, gets the 'audio distortion' at 44100Hz,
but is fine at 48000Hz.  However dvavi seems to badly mess up audio/video
synchronisation.  Has this been noted before, or can some expert on
this mailing list point me in the right direction to try and fix the
problem?

Are there any other utilities I can use to transfer, say, the AVI-type-2
file to the camcorder, bypassing the need to use dvavi to convert it into
a 'raw dv' file?  I've found a couple of Windows programs that can do
this, but I'm stymied there in that a) I don't know how to copy the
9.5GB AVI file from Linux to my VFAT filesystems (which have a 2GB
limit?) and b) neither transcode's avisplit or avidemux under Linux
can open the file also.  It would be wonderful if I could do this
under Linux, in one nice pipeline, rather than have to resort to interactive
Windows stuff, but at the moment I don't have any options that will
work!

Thanks,


Brad Rosser
b_r...@ya...


__________________________________
Do you Yahoo!?
The New Yahoo! Search - Faster. Easier. Bingo.
http://search.yahoo.com