[mythtv-users] 0.24 upgrade, audio buffer underruns

[Jean-Yves Avenard]

Hi

On 24 January 2012 04:36, James Orr <james.orr7 at gmail.com> wrote:
> I just upgraded from 0.23 fixes to 0.24.1.  If I have my audio set to 5.1 I
> get buffer underruns, setting it to stereo the audio is ok.
>
> This was not happening in 0.23.
>
> Here's the output from the frontend log, any ideas?
>
> 2012-01-23 12:25:34.921 AFD: Opened codec 0x90fc720, id(MPEG2VIDEO)
> type(Video)
> 2012-01-23 12:25:34.921 AFD: codec AC3 has 6 channels
> 2012-01-23 12:25:34.922 AFD: Opened codec 0x9103520, id(AC3) type(Audio)
> 2012-01-23 12:25:35.039 AO: Opening audio device 'iec958:CARD=SI7012,DEV=0'
> ch 6(6) sr 48000 sf signed 16 bit reenc 1

something is not right here...

it is trying to open the iec958 device in 6 channels mode, when a
iec958 is 2 maximum.

As there's no error when trying to open it, the issue is most likely
in the ALSA driver reporting this device has having 6 channels...

How did you select this audio device?

Go into the Settings -> General -> Audio Settings, and press the Scan
Audio Device button.
Browse the list generated. What does it say in the comment text when
you select iec958:CARD=SI7012,DEV=0

To get around this ALSA issue, go into A

> 2012-01-23 12:25:35.047 ALSA, Error: Unable to sufficiently increase ALSA
> hardware buffer size - underruns are likely

Well, the log does tell you you're going to get uderruns !

My guess is that this audio cards has only 64kB of hardware buffer,
and it's already set to 64kB

run mythfrontend with -v audio

re-run the settings, scan the audio devices, select iec958, then try
to play some audio and post the whole log here.

If you have selected that audio device through the generated audio
device list, and it is indeed configuring iec958 as a 6 channels, then
go into the Advanced Settings page, and check "StereoPCM"

This should fix all your issues..
Then raise a bug with ALSA, that the iec958 port on the SI7012 audio
card let you open it in 6 channels mode when it shouldn't.

JY