Re: [Alsa-user] period size and hardware limits
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From: Clemens L. <cl...@la...> - 2006-06-01 06:53:17
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Matthieu Redouin wrote: > I am trying to have short latency on my computer. I am using the > hda-intel driver and I am wondering about the output latency : > - with a buffer size of 64 and period of 2, I get around 1.5ms of output > latency > - with a buffer size of 64 and period of 4, I get around 4.2ms of output > latency ! I don't figure out this big difference. What are the units you're using here? Is your period size in bytes, in frames, or the number of period per buffer? And what are the sample format and rate? > Setting period size to 4 allows me to set buffer size to 16 and have an > output latency of 1.2ms, whereas period size of 2 and buffer size of 16 > gives me too many xruns (even with patched kernel). > So I am wondering if buff/period size of 64/2 was my hardware limits and > 16/4 settings only a trick handled by the driver ? If you're using the OSS emulation, the buffer parameters of the actual hardware might be different. Have a look into /proc/asound/card0/pcm0p/sub0/hw_params to see what the parameters used by the driver are. Regards, Clemens |