Re: Nodes, Widgets, ELD and Digital Surround 5.1 (HDMI) Output?

From: "Alexander E. Patrakov" <patrakov@gmail.com>
To: bencoxdev@gmail.com,
	David Henningsson <david.henningsson@canonical.com>,
	ALSA Mailing list <alsa-devel@alsa-project.org>
Subject: Re: Nodes, Widgets, ELD and Digital Surround 5.1 (HDMI) Output?
Date: Fri, 05 Dec 2014 15:49:00 +0500	[thread overview]
Message-ID: <54818D9C.5030100@gmail.com> (raw)
In-Reply-To: <4E4A612742FA4CEF85A52A8A16AADF78@Lyra>

05.12.2014 14:41, bencoxdev@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
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