[Ffmpeg-devel] dts decoding broken?

mail at kraymer.de mail
Fri Feb 9 17:52:52 CET 2007


I recently noticed that dts decoding doesn't behave like it did before.

Problem: Playing a 5.1 dts stream (either dvd or matroska in my case)
results in only 2 channels being played without downmix. I only have a
setup with two speakers, 5.1 ac3 streams are mixed down and it did the
same with 5.1 dts. Now, I only get 2 out of 6 channels without downmix,
even with -channels 2 and/or -af channels=2. What I get is mainly music
and background sounds, voices are missing.
I did some regression testing and it turned out that a change in ffmpeg,
namely commit -r 7839, introduced that behavior. Using recent mplayer svn
and changing ffmpeg externals to -r 7838 makes the problem go away..
I'm posting here because I couldn't reproduce the problem with ffplay.
That doesn't mean the problem doesn't exist in ffplay, ffplay simply fails
on the files I'm having the trouble with: a dvd vob (I think ffplay
doesn't cycle through the audio tracks (one ac3, one dts) and doesn't like
my matroska file at all, no sound with either -r7838 or 7839).
Regarding samples, I'm sure the problem is reproducable with every 2.0
setup and a dvd/mkv with dts track. If not, I'll upload parts of my
Please find mplayer output (with ffmpeg -r 7839) attached.


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