[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. 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

From: Alexander E. Patrakov 
Sent: Thursday, December 04, 2014 12:34 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?
04.12.2014 15:55, bencoxdev at gmail.com wrote:

  Hi Guys,
      Thank you for your input it's much appreciated.

      I have now produced the pulse audio log as suggested and it appears that 
  when an attempt to open the Digital Surround 5.1 device, it fails with a 
  "No such file or directory" error. Here is a snippet of the log showing the 
  error.

  (   0.456|   0.000) D: [pulseaudio] alsa-mixer.c: Looking at profile output:iec958-ac3-surround-51
  (   0.456|   0.000) D: [pulseaudio] alsa-mixer.c: Checking for playback on Digital Surround 5.1 (IEC958/AC3) (iec958-ac3-surround-51)
  (   0.456|   0.000) D: [pulseaudio] alsa-util.c: Trying a52:1 with SND_PCM_NO_AUTO_FORMAT ...
  (   0.456|   0.000) I: [pulseaudio] (alsa-lib)pcm.c: Unknown PCM a52:1
  (   0.456|   0.000) I: [pulseaudio] alsa-util.c: Error opening PCM device a52:1: No such file or directory

  So I guess the next question is what is responsible for producing the 
  required device?


This is not the correct device. This is a software encoder that is not installed on your computer. It will degrade audio quality by compression, eat CPU time, kill PulseAudio for exhausting the real-time budget, and is generally not needed on HDMI, because HDMI can transport PCM 5.1 streams just fine.

Please see my earlier reply how to force PulseAudio into opening the correct HDMI device.

-- 
Alexander E. Patrakov