[alsa-devel] Nodes, Widgets, ELD and Digital Surround 5.1 (HDMI) Output?

[bencoxdev at gmail.com]

Hi Alexander,
             Thanks for your efforts on this. Unfortunately I’m stuck with the current platform I have. However do not have to use pulse-audio and could use alsa directly.

    The pasuspender tests were done with a Yamaha HER-2866 surround sound amplifier, as the HDMI target device, the results were as given previously. 

    Any thoughts on using the alsa directly and how to set it up to offer the required output format in this scenario would be much appreciated.

Tia
Ben

From: Alexander E. Patrakov 
Sent: Monday, December 08, 2014 4:38 PM
To: bencoxdev at gmail.com ; David Henningsson ; ALSA Mailing list 
Subject: Re: [alsa-devel] Nodes, Widgets, ELD and Digital Surround 5.1 (HDMI) Output?
08.12.2014 19:40, bencoxdev at gmail.com wrote:
> Hi Alexander,
> Thanks for looking at this for me it is very much appreciated.
> Please see below the details from the all the logs; as you requested.
> I’ve had to omit a
> few details (vendor names and ID’s) as this project is pre-release and I
> am under N.D.A.

Unfortunately, you have leaked both the graphics vendor (through 
excessive blocking of it) and the TV/monitor vendor (through ELD). So 
you both broke the NDA and prevented me from troubleshooting further. I 
thought I needed the vendor IDs in order to match them against udev 
rules, but see below. Still, a fail-fail situation, especially since 
there are a lot of other hobby projects using development boards with 
the graphics and audio chips from the same vendor.

But indeed, there is information in the log that gives a big clue. You 
are using PulseAudio 1.1, and configured it not to use udev rules (so 
knowledge of a vendor ID is now useless). Also, it cannot autodetect 5.1 
PCM over HDMI with udev rules. It is also not supported anymore. My 
recommendation would be to either upgrade (which is impossible on the 
Ubuntu 12.04 platform) or to drop the use of PulseAudio altogether if 
you are stuck with this ancient userspace.

For enabling passthrough in PulseAudio, you would need to run 
pavucontrol and place a checkbox in the AC3 and DTS fields. Alternatively:

pactl set-sink-formats 0 'pcm;ac3-iec61937;dts-iec61937'

...where 0 is the sink index.

And also you need to find a player that supports this passthrough 
feature, and, if you are using GStreamer, also to make sure that the 
installed version supports passthrough. On such ancient platform, I'd 
recommend against it.

For PCM 5.1 (i.e. software decoding) with PulseAudio 1.1, you need a 
real 5.1 receiver and this command:

pacmd load-module module-alsa-sink device=hdmi:0,0 channels=6

> Using  pasuspender -- speaker-test -c6 -b 125000 -P2 -D "plug:'hdmi:X,Y'"
> X Y Result
> ------------------------------------------------------------------------------------------
> 0 0 Hiss left Front and Right Front, others silent
> (everything else) Playback open error: -2, No such file or directory

Try retesting plug:'hdmi:0,0' with a real 5.1 HDMI receiver (e.g. from 
Onkyo), not with a Samsung TV/monitor (that only advertises the presence 
of Front-Left and Front-Right channels and LPCM encoding in the ELD).

-- 
Alexander E. Patrakov