[MPlayer-dev-eng] SB Live/emu10k1 driver capabilities

[Stephen Davies]

On Thu, 22 Nov 2001, Arpi wrote:

> > b) Simply call SNDCTL_DSP_CHANNELS to request 6 channels, and write the
> sounds interesting. but doe sit work for non-5+1 cards too?
> I have "old" sblive, with only 2 stereo analog output on it.

I've got two SBLive cards - one is a "SBLive Player 5.1" and that has
altogether 6 analogue outs - 4 on a pair of stereo minijacks, the
subwoofer and centre on a "merged" digital/analogue

The other is a SB Live with 4 analogue outs on a pair of minijacks,
but no analogue/digital output.  Is that like yours?

I'm no expert - but I expect that mplayer could output full 6 channels to
either - non 5.1 users could set up the card to mix the LFE and centre
channels into the others.

> > Is it an easy change to do the ac3 decoding and pass all the channels
> > discretely?  It looks like "skip the downmixing" in libac3, perhaps some
> > tweaks in the libao2 drivers to deal with >2 channels?
> yes it needs changing both. but it should be easy.
> just define a new AFMT_ for 6channel out and extend libac3 (and dec_audio.c)
> to use this format.

I did a quick hack and made an ao_sblive that sets the card to 6 channel
mode.  Didn't change the actual audio - so the actual result was 3x speed
chipmunks in all 6 channels.  (Far out!)  But does seem to show that that
emu10k1 driver behaves as advertised.

Steve