[alsa-devel] regarding setting of fragment size in usbaudio driver

Amit Nagal helloin.amit at gmail.com
Sat Dec 11 10:16:30 CET 2010

Hi ,

i am using a OSS based usbaudio application for usb audio streaming .

my usb audio device is capture only device .

i want to set the fragment size of usbaudio alsa driver to reduce
latency problem coming in my application .

currently even if my application reads 4k data from userspace , i
observed driver will buffer for 100 ms data ( period size data )= 16 k
at 44100 frquency

and after driver  reads 16k data , read call will return with 4k data
.  so read() call remains blocked for 100ms which is causing some
latency problem .

i used SNDCTL_DSP_SETFRAGMENT  ioctl , but still driver behaviour to
buffer 100ms data remained same .

how driver's  fragment size in driver can be set to some less value in
OSS based application .

Can some patch  be implemented in kernel space to do that .?

Thanx & Regards
Amit Nagal

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