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

[bencoxdev at gmail.com]

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.  
There should still be sufficient information there for you, but if you do need anything 
specific please let me know and I’ll try requesting permission to release more details. 



1)      The ALSA-info log can be found at:- http://pastebin.com/L1JRz5yC

2)      The PulseAudio log is at:- http://pastebin.com/svJgR2dk

3)      Speaker test results:-

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
0              1              Playback open error: -2, No such file or directory
0              2              Playback open error: -2, No such file or directory
0              3              Playback open error: -2, No such file or directory
1              0              Playback open error: -2, No such file or directory
1              1              Playback open error: -2, No such file or directory
1              2              Playback open error: -2, No such file or directory
1              3              Playback open error: -2, No such file or directory
2              0              Playback open error: -2, No such file or directory
2              1              Playback open error: -2, No such file or directory
2              2              Playback open error: -2, No such file or directory
2              3              Playback open error: -2, No such file or directory
3              0              Playback open error: -2, No such file or directory
3              1              Playback open error: -2, No such file or directory
3              2              Playback open error: -2, No such file or directory
3              3              Playback open error: -2, No such file or directory



Ideally I would like to use pass-through mode because the intended display device can handle 
AC3 5.1 without issue; and so I would prefer not to put the decoding load onto the CPU (as 
it’s a low powered device).  I have been assured by the hardware vendor that the chip is 
capable of Digital pass-through of 5.1 audio.

------------------------------------------------------------------------------------------
TIA
Ben.

From: Alexander E. Patrakov 
Sent: Friday, December 05, 2014 10:49 AM
To: bencoxdev at gmail.com ; David Henningsson ; ALSA Mailing list 
Subject: Re: [alsa-devel] Nodes, Widgets, ELD and Digital Surround 5.1 (HDMI) Output?
05.12.2014 14:41, bencoxdev at gmail.com wrote:
> Hi Alexander,
> Thanks for looking at this for me. I have followed your earlier advice
> on setting up the correct HDMI device, unfortunately it doesn’t seem to
> have changed the situation.
>      I am trying to achieve AC3 pass-through and not decode/encode the
> audio. Any thoughts that you may have about this would be much appreciated.
> TIA
> Ben

First of all, some more information about your setup is needed.

1. ALSA-info:

wget http://www.alsa-project.org/alsa-info.sh
bash alsa-info.sh

This will upload the information to a central database and print out the 
link. Please post the link.

2. Full PulseAudio log

killall pulseaudio ; pulseaudio -vvv 2>&1 | tee -a pulse.log

(All in one line, with a ";" in the middle, in order to win the race 
against autorespawn. If it says "daemon already running", just try again.)

Please post the log on some pastebin and provide a link here.

3. An attempt to use speaker-test. Please try this command for all 
values of X from 0 to 3 and for all values of Y from 0 to 3:

pasuspender -- speaker-test -c6 -b 125000 -P2 -D "plug:'hdmi:X,Y'"

During one of the tests, it will hiss into your receiver. Please make a 
note of the correct X and Y values (for correlation with PulseAudio 
logs), and whether it hissed into each speaker separately.

Then, more information about your intentions is needed. Why are you 
talking about AC3 passthrough? I am asking because there are two ways to 
output 5.1 audio over HDMI: software decoding on a PC (which is IMHO 
preferable) and AC3 passthrough (i.e. hardware decoding on the receiving 
end, which requires a player that actually supports this feature when 
used with PulseAudio [which basically means "not mplayer"], and makes 
sense only on very slow CPUs or if the HDMI device is actually some dumb 
HDMI-to-SPDIF converter).

The correct profile to use is "Digital Surround 5.1 (HDMI) Output", 
which, due to a bug that I have already explained how to work around, is 
only available on "true" Intel and NVidia video cards as of PulseAudio 5.0.

-- 
Alexander E. Patrakov