[Ffmpeg-devel] dts decoding broken?

Måns Rullgård mans
Fri Feb 16 22:24:28 CET 2007

Uoti Urpala <uoti.urpala at pp1.inet.fi> writes:

> On Fri, 2007-02-09 at 19:19 +0200, Uoti Urpala wrote:
>> On Fri, 2007-02-09 at 17:52 +0100, mail at kraymer.de wrote:
>> > 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
>> That commit changes the decoder to output the full number of channels by
>> default. Unfortunately it also seems to completely remove the ability to
>> use the libdts downmixing functionality.
>> The rest of the channels are there and you can access them by explicitly
>> specifying some conversion to 2 channels with "-af pan" for example.
>> However having a way to use the libdts downmixing would be better.
> Does anyone intend to restore support for the downmixing functionality?

There is nothing to restore.  It used to *always* do downmixing with
no option to get all the channels.  How would an application request

> Can anything sanely use the current 6-channel output?

Works fine here.  Pretty much any motherboard less than a few years
old seems to have 6-channel or better sound onboard, and there are
many suitable PCI sound cards available.

> Is the channel order even documented anywhere in FFmpeg (outside
> libdts)?

The order is whatever ALSA expects.

I changed the libdts wrapper to decode all channels because Reimar was
whining.  Now you and Sebastian are whining instead.  It seems
impossible to satisfy all of you.

M?ns Rullg?rd
mans at mansr.com

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