[alsa-devel] Why there is no SNDRV_PCM_RATE_24000 in pcm.h
hi, guys I checked the include/sound/pcm.h in kernel and find this problem, it seemed strange, so many codecs support the 24000 sample rate, why there is no such definition. Any special concern?
Wei Kai wrote:
I checked the include/sound/pcm.h in kernel and find this problem, it seemed strange, so many codecs support the 24000 sample rate, why there is no such definition.
When the header file was created many years ago, 24000 Hz wasn't a common sample rate.
To support a sample rate that is not in that list of predefined rates, your driver should set the RATE_KNOT bit and call the snd_pcm_hw_constraint_list() function; see the section "Constraints" in the "Writing an ALSA Driver" document.
HTH Clemens
Thank you, Clemens.
2007/8/10, Clemens Ladisch cladisch@fastmail.net:
Wei Kai wrote:
I checked the include/sound/pcm.h in kernel and find this problem, it seemed strange, so many codecs support the 24000 sample rate, why there is no such definition.
When the header file was created many years ago, 24000 Hz wasn't a common sample rate.
To support a sample rate that is not in that list of predefined rates, your driver should set the RATE_KNOT bit and call the snd_pcm_hw_constraint_list() function; see the section "Constraints" in the "Writing an ALSA Driver" document.
HTH Clemens
participants (2)
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Clemens Ladisch -
Wei Kai