improper identifying of AC3 audio

[pikestaff@…]

Hi guys,
with the latest available win32 build of mplayer 1.0pre5 (bug also
applies to older versions), the usage of 'mplayer -identify' on a
videofile containing AC3 5.1 audio falsely reports 2ch. Example:

ID_FILENAME=t.a.t.u._-_all_the_things_she_said.vob
ID_VIDEO_FORMAT=0x10000002
ID_VIDEO_BITRATE=5400000
ID_VIDEO_WIDTH=720
ID_VIDEO_HEIGHT=480
ID_VIDEO_FPS=29.970
ID_VIDEO_ASPECT=1.3333
ID_AUDIO_CODEC=a52
ID_AUDIO_FORMAT=8192
ID_AUDIO_BITRATE=448000
ID_AUDIO_RATE=48000
ID_AUDIO_NCH=2
ID_LENGTH=421

granted, most musicvids are 2ch, but this one is true 5.1. Same thing happens
on any other 5.1 movie also.

so short version, ID_AUDIO_NCH=2 is always true, even when it isnt!

[bugfood-ml@…]

mplayer matrix.vob -identify -frames 0 -aid 128 2>/dev/null | \
egrep '(ID_AUDIO_NCH|AC3:)'
AC3: 5.1 (3f+2r+lfe) 48000 Hz 448.0 kbit/s
ID_AUDIO_NCH=2

ID_AUDIO_NCH appears to be the number of channels to which liba52 is downmixing
-- if you add '-channels 6', you will get ID_AUDIO_NCH=6 when using an audio ID
that has 6 channels.

mplayer matrix.vob -identify -frames 0 -aid 128 -channels 6 2>/dev/null | \
egrep '(ID_AUDIO_NCH|AC3:)'
AC3: 5.1 (3f+2r+lfe) 48000 Hz 448.0 kbit/s
ID_AUDIO_NCH=6

If the audio ID has fewer channels and you use '-channels 6', the correct number
will still be printed.

mplayer matrix.vob -identify -frames 0 -aid 130 -channels 6 2>/dev/null | \
egrep '(ID_AUDIO_NCH|AC3:)'
AC3: 2.0 (stereo) 48000 Hz 128.0 kbit/s
ID_AUDIO_NCH=2

So, I don't know if this is really a bug.

[Dominik 'Rathann' Mierzejewski]

Please provide a patch if you want this fixed. It's not really a bug.