With regard to the buffer size requiring more than x2 period size. If I understand ALSA correctly and to give you more understanding of my application. I require a large buffer of 2 seconds because the app that drives data to my application, via Ethernet UDP, can sometimes starve my application for a short while. It is my responsible to top up the buffer to its correct position. The period size is related to the hw interrupt which drives the ALSA callback function. I use this function to top up the buffer to correct level. Also I require more than 2 period sizes to do this. The algorithm may take several period sizes to gradually adjust the buffer level to correct level. On 8/31/07, Clemens Ladisch <cladisch@xxxxxxxxxxxxxx> wrote: > paul blakeley wrote: > > 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. > > The CS4299 is just an AC'97 codec; the buffer constraints depend on > the controller and/or the controller driver. > > > Therefore this makes it impossible for me to use with the ALSA > > callback mechanism, which I need to use for the design to work! > > ALSA cannot guarantee that any specific buffer/period size combination > is available on all sound cards. Your program must be able to work with > any value. > > There are several sound cards that require exactly two periods per > buffer. Why does your design need more? > > > By the way how do I find out which driver is assigned to a chipset? > > /proc/asound/modules > > > Can a driver be used on multiple chipsets? > > Yes, there are driver that can control several similar chipsets. > > > 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
