Hi , Thanx for the reply . Actually on my embedded target , i am not using arecord , but reading from (/dev/dsp0) capture data . i have 2 question : i used SNDCTL_DSP_GETBLKSIZE ioctl to find the fragment size of driver . i found it to be 16k . 1) now if the application reads 4k data from userspace , read call will remain blocked for audio driver's fragment size usb data read ( 16k) or app_request_size(4k) ? 2)time taken for read(4k) = time_taken(fragment size read ) or time_taken(app_request_size=4k) ? thanx & regards amit nagal On Mon, Dec 13, 2010 at 6:04 PM, Clemens Ladisch <clemens@xxxxxxxxxx> wrote: > Amit Nagal wrote: >> 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 . > > There is no extra buffer in the driver. > There seems to be something wrong with your algorithm. > > Does recording with the arecord tool work? > > > Regards, > Clemens > ------------------------------------------------------------------------------ Oracle to DB2 Conversion Guide: Learn learn about native support for PL/SQL, new data types, scalar functions, improved concurrency, built-in packages, OCI, SQL*Plus, data movement tools, best practices and more. http://p.sf.net/sfu/oracle-sfdev2dev _______________________________________________ Alsa-user mailing list Alsa-user@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/alsa-user
