[mythtv-users] .24 Audio results: mixed

Jean-Yves Avenard jyavenard at gmail.com
Sat Jun 19 04:21:22 UTC 2010


Hi

On 19 June 2010 14:03, Douglas Peale <Douglas_Peale at comcast.net> wrote:
> Does this mean that PulseAudio is capable of surround output but MythTV can't send surround to PulseAudio? Or can I change the
> PulseAudio configuration to support surround?

Pulse can do surround output, but you will probably only have success
with analog audio, and maybe HDMI LPCM..

Pulse resample everything to a unique sampling rate. The default is
44.1kHz . Most AC3 audio stream are 48kHz ; and resampled to 44.1kHz
would just sound like noise

Actually, this may be what you're experiencing when selecting the
IEC958 port...
Try upgrading to trunk >= 25136 and see if you still get digital noise...

Before this revision, if your audio card was only supporting say 48kHz
but you were feeding it AC3 at 44.1kHz, it would try to resample the
raw digital stream, instead of decoding the stream, resample it, then
re-encode it as AC3...

It could be one explanation on why when you use ALSA:iec958 you're
hearing garbage for AC3 content...



> That log file was not generated with PulseAudio, it was generated with ALSA:default since that is the only thing that works for
> AC3 passthrough.
> PulseAudio was just one of the many things that I tried that did not work.


I don't really care of logs when things work :)

>
> I'd have to understand it myself before I could come up with an explanation. I'm not there yet.

didn't my previous explanation help?


> See attached zip file.
> The sequence of events while generating the log file:
> run mythfrontend
> select liveTV
> A channel that was attempting to send AC3 was selected, I got noise.
> I changed the channel to one that was not sending AC3, I got sound.
> I exited LiveTV
> I exited mythfrontend.


> hide the signature and complain when it was not there.
> I'd rather have the signature there when I don't need it then not have it there when I do.

This is a public list, I would have assumed that your aim is mainly to
not annoy the other people your talking to, non-privately.
Having to manually trim the garbage pgp adds at both end of your
email, is annoying

Will have a look at your logs


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