Subject: [linux-audio-dev] Alsa OSS emulation
From: Jens M Andreasen (jens.andreasen_AT_chello.se)
Date: Mon Nov 22 2004 - 22:15:32 EET
Hi (Takashi?)!
The OSS emulation in ALSA is slightly wrong regarding number of
requested buffers. To quote from my own "notes to self" from own source:
/** Setting up the soundcard for CD-HiFidelity Stereo
*
*/
audio.path = "/dev/dsp";
audio.speed = SAMPLERATE;
audio.format = AFMT_S16_LE;
audio.is_stereo = TRUE;
// 3 buffers of 256 bytes == 3 * 64 (16bit) stereo samples
// 0x0002 buffers == n - 1, although Alsa (mis)interpretes oss buffers
// == n!!! Use 0x0003!
//
// 0008 bytes == log2(number of bytes in buffer), 2^8 == 256 == 64
// stereo samples;
audio.bufsize = 0x00030008;
... so ALSA UNDERSHOOTS the number of buffers BY ONE (which of course
will not work for RT-people on the edge.)
mvh // Jens M andreasen
PS: Thanks to the mdk10.1 beeing distributed on DVD by LinuxFormat this
month, work is ongoing for a clean alsa solution of my handyworks ...
DS
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