On Wed, May 27, 2009 at 9:47 PM, Cameron Stone camerons.lists@cse.unsw.edu.au wrote:
I've got a USB microphone application that I want to sample at 256000 8 bit samples per second so I can listen to bats. I know that my device can get close to that rate, but alsa seems to restrict sampling rates to 192kHz.
Is it possible to push the maximum sampling frequency higher? If so, where should I start looking?
For starters, try adding a 256K sample rate to include/sound/pcm.h:
118 #define SNDRV_PCM_RATE_176400 (1<<11) /* 176400Hz */ 119 #define SNDRV_PCM_RATE_192000 (1<<12) /* 192000Hz */ 120
and sound/core/pcm_native.c:
1762 1763 static unsigned int rates[] = { 5512, 8000, 11025, 16000, 22050, 32000, 44100, 1764 48000, 64000, 88200, 96000, 176400, 192000 }; 1765
Line numbers may vary, mine are from 2.6.27 kernel source.
Lee