[sclug] Re: Codec

Alex Butcher lug at assursys.co.uk
Mon Apr 5 12:12:58 UTC 2004

On Mon, 5 Apr 2004, Tony Sumner wrote:

> On Mon, Apr 05, 2004 at 10:53:23AM +0100, Alex Butcher wrote:
> > Sounds as though either the driver for your sound device doesn't support
> > variable output sample rates, you've got a limited sound device that doesn't
> > support variable output sample rates (i.e. it's not AC'97 2.1+ compliant),
> > or (possibly), some other process has a lock on /dev/dsp. Do you have KDE's
> > arts or esd running, perhaps? ... Windows probably works because
> > its driver is doing resampling to 48KHz in software
> It's either the first or second (the device is 2.1 compliant but not
> 2.1+). But this makes Patrick's point; Windows 'just works' and RH
> could too if the driver did resampling.

I would imagine the reasons why the Linux driver doesn't do resampling is
because, like software mixing, the amount of CPU time needed to do it is
unbounded, and as such, in the opinions of Linus et al, is not a suitable
thing to do in kernel space.

Windows kernel hackers and driver authors obviously have no such concerns.

Go figure.

> So a naive user like me has to wait months and read lots of stuff before
> getting the right answer from an expert, which is (I guess) to buy a sound
> card with driver.

Alternatively, you could try ALSA if you're not using it already. I had some
issues with OSS' i8x0 sound driver that ALSA's i8x0 driver didn't have.
Maybe it'll be the same for you.

> Re this AC97 Codec. I have a file endoftheworld and I played it like this:
>   Script started on Mon Apr  5 13:20:55 2004
>   % file endoftheworld
>   endoftheworld: RIFF (little-endian) data, WAVE audio, Microsoft PCM, \
>   8 bit, mono 8000 Hz
>   % play endoftheworld 
>   sox: Unable to set audio speed to 8000 (set to 48000)
>   Script done on Mon Apr  5 13:21:28 2004
> What I got was a little white noise and then the 'song'. Does that tell
> me whether it is the first thing or the second? (... thinks) Sounds as
> if the codec is fixed at 48kHz, play does resampling but RealPlayer
> (which is what plays BBC programmes) doesn't.

Could very well be the case.

> Anyway I think I can afford to get a sound card and find out. Thanks for
> your help.
> Tony

Best Regards,
Alex Butcher      Brainbench MVP for Internet Security: www.brainbench.com
Bristol, UK                      Need reliable and secure network systems?
PGP/GnuPG ID:0x271fd950                         <http://www.assursys.com/>

More information about the Sclug mailing list