Mailing List Archive: Weird Audio Problems

Weird Audio Problems

Oct 29, 2002, 9:46 AM

Post #1 of 3 (1222 views)

I've been trying to get mythtv working but have been running up against a
weird intermittent issue with the audio.

The box I'm using has integrated audio and uses the VIA686 driver.

My initial attempts at getting mythtv working had problems with the kernel
audio driver ... it would hang attempting to initialize the audio
component (actually, it would often hang the system). Anyway, I decided
to punt the shipping driver for the ALSA version. This worked ... sort of
... well, at least it didn't hang.

Now, when starting the mythtv app, I get this:

$ mythtv

Probed: /dev/video0 - Television
Probed: /dev/video0 - Composite1
Changing from None to WatchingLiveTV
ran out of free AUDIO buffers :-(
ran out of free AUDIO buffers :-(
ran out of free AUDIO buffers :-(
...

on for a while until it either segfaults or a video window comes up with
extremely choppy video.

The only problem with this is that it doesn't *always* happen. About 1
out of 8 attempts will succeed. TV playing will be flawless, captures
perfect, ... it just works.

I like what I see enough when it does work to want to work through the
issue. I messed around a bit with uping the buffers in libNuppelVideo
without much luck.

Any clues would be helpful.

Re: Weird Audio Problems [ In reply to ]

radford+myth at blackbean

Oct 29, 2002, 10:16 AM

Post #2 of 3 (1200 views)

Permalink

On Tue, Oct 29, 2002 at 11:46:59AM -0500, rlbpublic@rlblounge.mine.nu wrote:
> I've been trying to get mythtv working but have been running up against a
> weird intermittent issue with the audio.

Me too!

> The box I'm using has integrated audio and uses the VIA686 driver.

I'm using snd-cmipci, so it might not be specific to the card.

> $ mythtv
>
> Probed: /dev/video0 - Television
> Probed: /dev/video0 - Composite1
> Changing from None to WatchingLiveTV
> ran out of free AUDIO buffers :-(
> ran out of free AUDIO buffers :-(
> ran out of free AUDIO buffers :-(
> ...

> on for a while until it either segfaults or a video window comes up with
> extremely choppy video.

I get this once in a while as well. :-(

> The only problem with this is that it doesn't *always* happen. About 1
> out of 8 attempts will succeed. TV playing will be flawless, captures
> perfect, ... it just works.

Yep.

-Jim

Re: Weird Audio Problems [ In reply to ]

tarek at tarek

Oct 29, 2002, 3:53 PM

Post #3 of 3 (1224 views)

Permalink

Well, this problem is a "full duplex" problem..

If you think about it, your sound card has to constantly be recording and
then playing back.. if it can't achieve "full duplex", then this doesn't
happen.. and so the audio buffers run out.. Yes, this is not the *only*
reason that audio buffers run out.. You can google for some previous
attempts to fix this problem.. This is, however, the most common reason I
have found in my experiences.. So, what can you do? Well, I don't know..
but I'll tell you what I did: I got a new sound card.

Many cheapo sound cards nowadays have full duplex and alsa support for
said full duplex (www.alsa-project.org to verify).. Only problem is they
have horrendous Signal-to-Noise most of the time.. oh well.. you win some,
you lose some : )

If myth *SOMETIMES* works and *SOMETIMES* doesn't in terms of sound, then
it could be that you're overloading the system.. here, extra buffers
(dma_buffers= in most cases) might sort out your problem.. Just keeping
the strain off your system might also help.. When the computer is
complaining of buffer problems, it'll slow down the video and such..

tarek : )

> On Tue, Oct 29, 2002 at 11:46:59AM -0500, rlbpublic@rlblounge.mine.nu wrote:
> > I've been trying to get mythtv working but have been running up against a
> > weird intermittent issue with the audio.
>
> Me too!
>
> > The box I'm using has integrated audio and uses the VIA686 driver.
>
> I'm using snd-cmipci, so it might not be specific to the card.