On Wed, 29 Oct 2003, Roman Roschin wrote:
> Hello!
>
> My name is Roman Roschin. I'm developing a database tool for ambulance
> service running on Linux. Between others, the program has a
> functionality of audio recording for the incoming calls.
>
> I'm trying to use ALSA 0.9.8 on the Gigabyte GA-8LS533 Motherboard
> with
> the integrated audio codec AC97 Realtek ALC101.
>
> The problem is that ALSA allocates (for recording) only 2x2 Kb buffer
> on 8kHz frequency, or 8x2 Kb in 44 kHz frequency. Unfortunately, such
> small buffer is not enough for my purposes.
Note that if your codec does not support resampling, then you must take in
account that ALSA does sample rate conversion for you, thus multiply the
buffer size with this difference - for example:
8000Hz mono 16-bit to 48000Hz stereo 16-bit conversion
4096 * (48000 / 8000) * 2 * 2 = 24576 * 2 * 2 = 98304
(it's the most close value to 128kB when buffer size for application
must be power of two).
Also note that intel8x0 hardware has fixed support for stereo 16-bit (you
cannot change it).
> 2. Is there a possibility to distinguish motherboards/integrated
> chipsets with large enough buffers without buying them and testing?
You can change the maximum buffer size in sources. See for
buffer_bytes_max string.
Jaroslav
-----
Jaroslav Kysela <[EMAIL PROTECTED]>
Linux Kernel Sound Maintainer
ALSA Project, SuSE Labs
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