[MPlayer-users] Identifying Surround Sound with MPlayer
Corey Hickey
bugfood-ml at fatooh.org
Sun Feb 10 06:45:54 CET 2008
Gary C. New wrote:
> Is it possible to identify surround sound with
> mplayer? I am able to identify what audio codec is
> used with a given a/v file through ID_AUDIO_CODEC, but
> it does not specify how many channels are used. Do
> all a52 encoded files use all 6 channels or do they
> have the option of using the minimum 2 channels?
No, liba52 is a decoder for the AC3 format, and AC3 comes in many
flavors--and some of the different flavors even have the same number of
channels.
If you use 'mplayer -v' you can see lines like these examples:
AC3: 2.0 (dolby) 48000 Hz 192.0 kbit/s
AC3: 2.0 (stereo) 48000 Hz 192.0 kbit/s
AC3: 5.1 (3f+2r+lfe) 48000 Hz 448.0 kbit/s
DTS: 5.1 (3f+2r+lfe)
That should suffice for details about AC3 and DTS; for the more general
case, try looking at ID_AUDIO_NCH (which seems to be printed twice, so
use the last one). That refers to the number of output channels, though,
so you should probably add '-channels 6' to your command line;
otherwise, some decoders (such as liba52) may automatically downmix and
you'll see ID_AUDIO_NCH=2 for a 6-channel track.
-Corey
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