avformat/mov : (fix) dv audio is be pcm

[aleniuk]

fixes playback of
http://samples.ffmpeg.org/ffmpeg-bugs/trac/ticket4671/dir1.tar.bz2

./ffplay -enable_drefs 1 -i dir1/movie2.mov

[bcoudurier]

Thanks a lot for the patch! Quick question, have you tested with a file with 'dvca' fourcc ? There might be a difference between 'dvca' and 'vdva', when I originally wrote that code, I believe I tested properly :)

[aleniuk]

no, I didn't, and don't have any.
And I haven't ever meet file like what we're testing here, it's just I send a patch similar to your "dv is actually be pcm" to ffmpeg , and Michael Niedermayer found a case with this file.