[MPlayer-users] Hardware AC3 and DTS

[Peter Hutnick]

I've added a Chaintech AV710 to my system.  I've connected it to my
receiver via TOSLINK.  I'm trying to work out the correct incantation
to pass Dolby Digital (and DTS if possible) through when I play DVDs.

The man page indicates that I shouldn't specify a device with the -ac
hwac3 option.  I tried "mplayer -ac hwac3 -aid 128 dvd://" which
produces noise (which I take to be AC3 being interpreted as PCM) on
the line-out port on my sound card.

I tried "mplayer -ao alsa:device=hw=0.1 -ac hwac3 -aid 128 dvd://"
which produces similar noise on my receiver, which stays in "LINEAR
PCM" mode.

I get the following output on the console

==========================================================================
Forced audio codec: hwac3
Opening audio decoder: [hwac3] AC3/DTS pass-through S/PDIF
No accelerated IMDCT transform found
hwac3: switched to AC3, 448000 bps, 48000 Hz
AUDIO: 48000 Hz, 2 ch, ac3, 448.0 kbit/29.17% (ratio: 56000->192000)
Selected audio codec: [hwac3] afm:hwac3 (AC3 through S/PDIF)
==========================================================================

   [snip (so far, so good)]

==========================================================================
Checking audio filter chain for 48000Hz/2ch/ac3 -> 48000Hz/2ch/ac3...
AF_pre: 48000Hz/2ch/ac3
alsa-init: 1 soundcard found, using: hw:0,1
alsa-init: format ac3 are not supported by hardware, trying default
alsa-init: unable to set format: Invalid argument
alsa: 48000 Hz/2 channels/4 bpf/32768 bytes buffer/Signed 16 bit Little Endian
AO: [alsa] 48000Hz 2ch s16le (2 bps)
Building audio filter chain for 48000Hz/2ch/ac3 -> 48000Hz/2ch/s16le...
[format] Sample format big-endian AC3 not yet supported
[libaf] Reinitialization did not work, audio filter 'format' returned
error code -2
Couldn't find matching filter/ao format!
Starting playback...

I tried xine for my own amusement.  I set it to pass through and it
works great, but I don't want to use xine, I want to use mplayer!

Thanks in advance for any help.

-Peter