On Fri, 03 Aug 2018 08:28:37 +0200, Yu-hsuan Hsu wrote: > > Hi all, > > I have a question about the period we set in hw_params. I found different > boards may have different explanations about it. I have two guesses about > its meaning. > > 1. The period_size is the size of each hardware's consumption. If we set > period size to N, the pcm will consume N frames each time. > > 2. The period_size is the size to control when hardware call interrupt. If > we set period size to N, the pcm consume frames in its step. When the > number of frames it consumes more than N, it will call interrupt. 2 is the correct answer. HTH, Takashi > We can use snd_pcm_avail function to check the real available frames in > the device. If guess 1 is correct, the size of consumption should be fixed. > Else, setting period_size is nothing to do with hardware's > consumption. I've checked some boards and found that each board has > different behavior (Most of them meet guess 2). I'm confuse which one is > correct. Thanks! > _______________________________________________ > Alsa-devel mailing list > Alsa-devel@xxxxxxxxxxxxxxxx > http://mailman.alsa-project.org/mailman/listinfo/alsa-devel > _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
