[Ffmpeg-devel] Re: dv video format with 32 kHz audio?

Roman Shaposhnick rvs
Wed Apr 26 03:56:33 CEST 2006

On Sat, Apr 22, 2006 at 12:39:41AM +0300, Mikko Rapeli wrote:
> (wasn't subscribed to the list so copy-pasting a bit)
> Roman Shaposhnick rvs at sun.com wrote
> > 32 kHz in DV is quite evil. Stay away from it. Really, why do
> > you have to use it, anyway ?
> I was a succer and bought a Sony DCR-PC106E, which only does 12 bit
> samples at 32 kHz in stereo mode, and now my disk is full of raw videos
> from the camera. 

  I kinda hate Sony lately, with all the crap they've been pushing onto
  consumers I wonder whether an engineering core is still left in
  that bottomless pit of despair.

> If I had the disk space with current projects I'd convert
> these videos with ffmpeg to 48kHz, but I don't. Yet. I'm almost ready to
> throw money on this issue, but a software solution would be nice. 

  Well, its rather easy to just inject a proper audio into an existing
  DV frame-set without wasting extra disk space. I think I still might
  have a handy utility which does that on my laptop. Will let you know.

> > Yeap. Supporting 32kHz requires a different encoding of audio
> > samples.
> I don't know much about the dv format, but I suppose the audio codec 
> CODEC_ID_PCM_S16LE would stay the same and only the number of audio samples
> per video frame would be smaller, plus the header changes to indicate a
> 32kHz sample rate. Does this translate to changes in libavformat/dv.c?

  Its more than that -- you also need to apply what's being done
  in dv_audio_12to16 and futz with the proper # of samples per frame.

> Is there a better dv format description than
> http://en.wikipedia.org/wiki/DV on the net?

  Yes ;-) http://www.adamwilt.com/


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