[MPlayer-users] Re: Mplayer & DD5.1 via SPDIF - I have only DD2.0: why ?

[sasza]

Dominik 'Rathann' Mierzejewski <dominik <at> rangers.eu.org> writes:

> 
> On Monday, 26 December 2005 at 22:46, Sasza wrote:

> > hwac3: switched to AC3, 448000 bps, 48000 Hz
> > AUDIO: 48000 Hz, 2 ch, 16 bit (0x400), ratio: 56000->192000 (448.0 kbit)
> 
> Looks like source audio is only stereo, so you won't get 6 channels unless
> you explicitly add them and mix them. See -af surround or -af pan.

Let me try understand few things, ok 

How those options are related to "-channels 6" option ?
Is it means that "-channels 6" tels mplayer to get 6 channels from AVI stream,
and "-af surround" tels to mix them to single outputing stream (surround format
in this case)?     

Is it true, that mplayer w/o any "-af" option always send 2.0 format ? 

BTW: What is source of following info: mplayer or alsa: 
"....Checking audio filter chain for 48000Hz/2ch/16bit -> 48000Hz/6ch/8bit...
AF_pre: af format: 2 bps, 2 ch, 48000 hz, big endian AC3
AF_pre: 48000Hz 2ch AC3
alsa-init: soundcard set to surround51
alsa: 48000 Hz/6 channels/12 bpf/61440 bytes buffer/Signed 16 bit Little Endian
AO: [alsa] 48000Hz 6ch AC3 (1 bps)
Building audio filter chain for 48000Hz/2ch/16bit -> 48000Hz/6ch/8bit...
Starting playback..."


> > ....................
> > Software: VirtualDubMod 1.5.10.1 (build 2439/release)
> > ==========================================================================
> > Opening audio decoder: [liba52] AC3 decoding with liba52
> > AC3: 5.1 (3f+2r+lfe)  48000 Hz  448.0 kbit/s
> > AUDIO: 48000 Hz, 6 ch, 16 bit (0x10), ratio: 56000->576000 (448.0 kbit)
> 
> But not here. This is 5.1 audio.

So here mplayer is decoding 5.1 internally, and sending 5.1 to alsa - right ?.
Why then alsa is outputing on spdif only 2.0 if is getting full 5.1 ?
 
> > Selected video codec: [ffodivx] vfm:ffmpeg (FFmpeg MPEG-4)
> > ==========================================================================
> > Checking audio filter chain for 48000Hz/6ch/16bit -> 48000Hz/6ch/16bit...
> > AF_pre: af format: 2 bps, 6 ch, 48000 hz, little endian signed int
> > AF_pre: 48000Hz 6ch Signed 16-bit (Little-Endian)
> > alsa-init: soundcard set to surround51
> > alsa: 48000 Hz/6 channels/12 bpf/61440 bytes buffer/Signed 16 bit Little 
> > Endian
> > AO: [alsa] 48000Hz 6ch Signed 16-bit (Little-Endian) (2 bps)
> > Building audio filter chain for 48000Hz/6ch/16bit -> 48000Hz/6ch/16bit...
> > Starting playback...
> 
> In this last case, too? It looks to me it's playing 6ch audio on 6ch output
> (decoded, not passed through though).

You mean analog 6ch output, right ?