I have successfully increased the amount of buffer by writing a new value into /proc/asound/cardX/pcm*/sub*/prealloc. For a mono .wav file I was able to successfully change this from 64 to 512. I was really happy with this. I presume this value is in the units of kBytes? And that this value needs to be 2 to the n. ie 16,32,64 etc? Dont know why but I couldn't change this to > 512, do you? I also tried this change on a stereo .wav file but it didnt scale as I thought. In fact I could only set this to 32! Which doesnt make sense. Do you know why? On 8/30/07, paul blakeley <pblakeley@xxxxxxxxx> wrote: > Thanks for replying. > > I am writing an application that is generic enough to a number of > different drivers. If thats possible! I am trying to achieve a 2 > second of buffer for a number of different sample rates. This means > that for a sample rate of 44.1KHz I require a buffer size of 88.2K > frames!!!! For all the different types of sound cards that I have > used I havent seen a buffer size > 16K frames : ( > > I have noticed that various drivers have certain behaviour which makes > writing a application that is generic for all drivers very difficult. > For example for an intel chipset I have found that the driver was very > versatile and allowed me to choose various period sizes for different > buffer sizes. Whilst the driver for the CS4299 chipset, although > allows a buffer size of upto 16K the period size has to be half that > value. Therefore this makes it impossible for me to use with the ALSA > callback mechanism, which I need to use for the design to work! > > By the way how do I find out which driver is assigned to a chipset? I > understand that I can use 'lsmod'. Can a driver be used on multiple > chipsets? You will have to excuse my knowledge on this : ) > > On 8/29/07, Clemens Ladisch <cladisch@xxxxxxxxxxxxxx> wrote: > > paul blakeley wrote: > > > Is it possible to increase the buffer size of a ALSA driver? > > > > Yes. No. Er, maybe. > > > > Each driver has a certain limit for the buffer size. The ALSA framework > > preallocates memory for the buffer, but usually only half the limit. > > You can increase the amount by writing a new value into > > /proc/asound/cardX/pcm*/sub*/prealloc. > > > > The limit is sometimes just an arbitrary value invented by the driver > > writer, but in many cases a hard limit of the hardware. > > > > What driver are you using? > > > > > > Regards, > > Clemens > > > ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ Alsa-user mailing list Alsa-user@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/alsa-user
