[MPlayer-users] [Ubuntu] Help wanted: DTS and AC3 passthrough play on only 2 speakers

[Norman Ramsey]

I'm successfully using mplayer's DTS and AC3 passthrough feature, but I'm
getting
output only on the two front speakers.  Here follows information about my
system,
plus detailed symptoms and outputs.

I'm running mplayer 1.0rc4-4.4.5 on Ubuntu Maverick.  I'm running with ALSA
drivers 1.0.23.
A pulseaudio daemon seems to be running.

I'm using source material I've encoded myself as well as test files
downloaded
from http://www.lynnepublishing.com/surround/.

Output is going from an S/PDIF header on the motherboard through an optical
TOSLINK
cable to a Yamaha home theater receiver.  The receiver plays both Dolby
Digital and DTS
encoded DVDs on all speakers, so the problem lies with the computer.   The
receiver has
a visual indicator that distinguishes three kinds of digital signal:

  - PCM
  - Dolby Digital
  - DTS


My first command is:

  mplayer -nolirc -ao alsa -afm hwac3 www_lynnemusic_com_surround_test.ac3

This is a test file designed to play on all five main speakers.  However,
only
the front speakers play.  The "rear left" and "rear right" signals play on
the
front speakers, indicating that something somewhere is mixing 5.1 channels
down to 2 channels.   The receiver indicates Dolby Digital as expected.
The output from mplayer looks like this:


MPlayer 1.0rc4-4.4.5 (C) 2000-2010 MPlayer Team

Playing www_lynnemusic_com_surround_test.ac3.
libavformat file format detected.
[ac3 @ 0x98a4f60]max_analyze_duration reached
[ac3 @ 0x98a4f60]Estimating duration from bitrate, this may be inaccurate
[lavf] stream 0: audio (ac3), -aid 0
==========================================================================
Trying to force audio codec driver family hwac3...
Opening audio decoder: [hwac3] AC3/DTS pass-through S/PDIF
hwac3: switched to AC3, 448000 bps, 48000 Hz
AUDIO: 48000 Hz, 2 ch, ac3be, 448.0 kbit/29.17% (ratio: 56000->192000)
Selected audio codec: [hwac3] afm: hwac3 (AC3 through S/PDIF)
==========================================================================
[AO_ALSA] Format ac3be is not supported by hardware, trying default.
AO: [alsa] 48000Hz 2ch ac3le (2 bytes per sample)
Video: no video
Starting playback...
A:   1.6 (01.6) of 9.3 (09.2)  0.1%


I'm concerned about the message "Format ac3be is not supported by hardware;
trying default".  However, the receiver does indicate that it is in Dolby
Digital mode,
and I did find a forum post somewhere whose author said he got 5.1 sound
despite
the presence of that message.


I also tried DTS passthrough.  Here I had to use a file I encoded myself,
with
this command:

    mplayer -nolirc -vc ffh264vdpau -vo vdpau -ao alsa -afm hwac3
blackest-dts.mkv

And here's the output:


MPlayer 1.0rc4-4.4.5 (C) 2000-2010 MPlayer Team

Playing blackest-dts.mkv.
libavformat file format detected.
[matroska @ 0x99cc040]Estimating duration from bitrate, this may be
inaccurate
[lavf] stream 0: video (h264), -vid 0
[lavf] stream 1: audio (dca), -aid 0
VIDEO:  [H264]  720x478  0bpp  29.917 fps    0.0 kbps ( 0.0 kbyte/s)
Clip info:
 doctype: matroska
==========================================================================
Forced video codec: ffh264vdpau
Opening video decoder: [ffmpeg] FFmpeg's libavcodec codec family
Selected video codec: [ffh264vdpau] vfm: ffmpeg (FFmpeg H.264 (VDPAU))
==========================================================================
==========================================================================
Trying to force audio codec driver family hwac3...
Opening audio decoder: [hwac3] AC3/DTS pass-through S/PDIF
hwac3: switched to DTS, 1536000 bps, 48000 Hz
AUDIO: 48000 Hz, 2 ch, ac3le, 1536.0 kbit/100.00% (ratio: 192000->192000)
Selected audio codec: [hwdts] afm: hwac3 (DTS through S/PDIF)
==========================================================================
AO: [alsa] 48000Hz 2ch ac3le (2 bytes per sample)
Starting playback...
[VD_FFMPEG] Trying pixfmt=0.
Movie-Aspect is 1.78:1 - prescaling to correct movie aspect.
VO: [vdpau] 720x478 => 852x478 H.264 VDPAU acceleration
[VD_FFMPEG] XVMC-accelerated MPEG-2.
A:  78.4 V:  78.4 A-V:  0.000 ct: -0.000   0/  0  0%  0%  0.5% 2 0
Exiting... (Quit)



Here there are no error messages, and the receiver correctly lights up the
DTS indicator.  But the rear speakers are dead silent.


I've spent four hours searching the web and trying different things.
I'm at my wits' end.  Not sure if the problem lies with mplayer or
elsewhere.
I'd welcome any and all help.


Norman Ramsey