At Tue, 7 Nov 2006 09:15:42 +0200, Assaf Hoffman wrote: > > Hi, > Yes, I read the "Writing an ALSA driver". > Nevertheless, it seems that the stack can configure the HW with two > independent parameters: Buffer size and period size. Yes, but they are _not_ necessarily independent with each other. You can set correleation/limitations between them (called "hw_constraints"). For example, you can limit the number of periods to 2 or 4. That's what Lee suggested. > In such a system > where you get the interrupts on a portion of the DMA buffer size those > parameters depend on each other. How the ALSA stack can know that? Takashi > Thanks. > > -----Original Message----- > From: Lee Revell [mailto:rlrevell@xxxxxxxxxxx] > Sent: Tuesday, November 07, 2006 9:08 AM > To: Assaf Hoffman > Cc: alsa-devel@xxxxxxxxxxxxxxxxxxxxx; Rita Shtern > Subject: Re: ALSA HW buffer managment > > On Tue, 2006-11-07 at 08:48 +0200, Assaf Hoffman wrote: > > Hi, > > As I understood, ALSA buffer management uses the 'periods' notion to > > control the latency between SW stack and HW DMA. > > My HW is not capable of interrupting the SW on a period basis. The > only > > interrupt HW generates is on half or quarter of the DMA buffer (for > > example, in capture, after each half of the buffer is filled with > > samples the HW will signal interrupt). > > "Period" just refers to the interval between interrupts. So your > hardware supports either 2 or 4 periods per buffer. > > Did you read "Writing an ALSA driver"? > > Lee > > > ------------------------------------------------------------------------- > Using Tomcat but need to do more? Need to support web services, security? > Get stuff done quickly with pre-integrated technology to make your job easier > Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo > http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 > _______________________________________________ > Alsa-devel mailing list > Alsa-devel@xxxxxxxxxxxxxxxxxxxxx > https://lists.sourceforge.net/lists/listinfo/alsa-devel > ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/alsa-devel
