[Mplayer-users] Audio problem: it has 'wheezing' artifacts

Nick Kurshev nickols_k at mail.ru
Wed Jun 6 13:00:12 CEST 2001

Hi, Alex Kanavin!

On 2001-06-05 16:14:40 you wrote:

>> Did you tuning of your Linux driver for SB16?
>> It seems that you have misconfigured Linux driver.
>> I have Creative SB16 (Vibra 16c) PnP but my card never used dma 3
>> (16-bit DMA channel).
>Ok, my fault. smpeg actually has the same problem. It's not the soundcard
>or mplayer, but the videocard or it's driver. (s3 virge/dx 2mb). If I run
>X in a smaller resolution (640x480 rather that 1024x768), or decrease the
>refresh rate (60 Hz rather than 85) the sound plays perfectly. Somehow,
>Windows 98 manages to play everything fine in any resolution. I think I
>should report this to the XFree virge driver maintainer. Or get a better
>card :)
>By the way in Windows 98 the picture is much smoother, this is especially
>noticeable during credits, that move from bottom to top. I suppose that's
>because Windows can achieve a much better a/v sync. Is it true? Is it
I have almost same configuration:
S3VirgeDX-PCI + SB16PnP + Duron-750 + 256RAM
I use mplayer with SDL output: -vo sdl. And it works for me in real-time
with 600x400 (4:3) 48000 DivX-MPEG4 streams.
A-V resync problem was in mplayer but it seems that Arpi've fix it.
At least it don't occur for me now (I use mplayer from CVS).
But when I try to run any windoze player under my NT4.0 then
they can't play me in realtime even 320x200 stream with sound.

>> Second: by default Linux assigned 1K dma buffer for SB16.
>> Did you increase that (at least up to 32K)?
>If you're talking about the dmabuf=1 option, it's not setting the buffer
>size (that's fixed to 64K), but tells the driver whether the DMA buffer
>should be persistent. The info is from
>/usr/src/linux/Documentation/sound/README.modules. And yes, I have that
>option set to 1 in modules.conf.

Yes, I know it. It's useful only for linux-2.2 kernels where this option undocumentedly
changes size of dma_buf. At least on my old hardware (K6-200) it had perform silence in
my speakers and uninterruptable playback of mp3 but before sound could be interrupted
by pressing F3 in Midnight.
But if you look at /usr/src/linux/Documentation/sound/ then you can find there that 16-bit DMA channel
can be only >= 5 but not 3 (Althrough 3 is present there in one sample).

Best regards! Nick (2001-06-06 10:44:17)

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