[mythtv-users] Making Pulse play nice with IEC958/SPDIF (Coax or Optical) connections

[Jean-Yves Avenard]

Hi

On 19 February 2012 11:48, Doug Vaughan <r.d.vaughan at rogers.com> wrote:
>   Hopefully the information below will help others that experience
> problems with Pulse audio and their IEC958/SPDIF connected audio equipment.
> There may be other ways to resolve the issues I experienced but I never
> found them. I am in no way blaming MythTV as the issues sighted below happen
> independent of MythTV.
>
> Plug-in tested with: Ubuntu 11.04 and MythTV pre-0.25 (fully up-to-date)
>
> Summary:
> 1) Support for AC3 5.1 and DTS 5.1 surround despite using Pulse audio

I had heard that pulse now supported digital passthrough..
Haven't tested myself

> 3) Frequently a MythTV commercial skipping/fast forward caused
> intense white noise to come from the surround audio system. I am not sure
> if this has been full eliminated but it definitely occurs less often.

This can be avoided if you change the default pulse sampling rate from
44100 to 48000
in /etc/pulse/daemon.conf ; change or add the line:
default-sample-rate = 48000

BTW, if you leave it to the default (44100), that means pulse will
have to decode most digital audio it gets, resample and re-encode, as
most of them are 48kHz

> 4) No combination of MythTV audio settings seemed to eliminate audio
> lockouts.
> 5) HDPVR AC3 5.1 recordings would only playback in stereo due to my
> chose to use the MythTV "Pulse (default)" audio setting. This was the
> only setting that reduced the number of audio lockouts.

myth reported the number of channels reported by Pulse.
if myth shows stereo, it's because Pulse reports supporting stereo.