[FFmpeg-devel] [PATCH 2/2] DCA - fix downmix

Carl Eugen Hoyos cehoyos
Wed Jul 28 14:58:53 CEST 2010

Nick Brereton <nick <at> nbrereton.net> writes:

> On 28 Jul 2010, at 11:00, Carl Eugen Hoyos <cehoyos <at> ag.or.at> wrote:

> > Could you comment on the remaining problems: 
> > Afaict, the 4.0 sample we have
> > (A-codecs/DTS/Edward.Scissorhands.x264.DTS-4.0-48_24.mkv on
> > samples.mplayerhq.hu) ends up with wrong channel order if converted to wav.
> What's the correct order? With current code converting to wav I see
> L, R, C, S in that order. (./ffmpeg -i
> Edward.Scissorhands.x264.DTS-4.0-48_24.mkv out.wav)

How do you "see" the order of the resulting wav file?
What I tried is to play the wav file with ffplay, mplayer and aplay (except for
ffplay both analogue and over hdmi) and I heard the center signal (the one with
the sound when the egg-halfs are pulled apart after ten seconds) from the (left)
surround box.

> > And if I convert one of the "new" seven channel samples (I mean the samples
> > that were 6-channel before your patches) to wav, nothing plays them
> > correctly. afaict
> I'm not seeing problems going to .wav files - is this another case?

Before your patches, both lotr_5.1_768.dts and last_stand.mkv were identified as
6-channel and if converted to wav, the resulting file played "fine" (wrt channel
order) with ffplay, mplayer and aplay (again analogue and via hdmi).
Now the samples (at least with -acodec copy -f dts) are (correctly) identified
as seven channel, but the resulting wav file sounds completely wrong (center
channel missing?) with mplayer and aplay - this time only analogue, because at
least my receiver-hdmi combination (Geforce 210 - KRF-V7300D) does not accept
seven channel wav, only 1, 2, 4, 6 and 8).

Thank you for looking into this, Carl Eugen

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