Raymond Toy wrote:
I'm working on an application where I'd like to have relatively fixed timing between calls to snd_pcm_writei.
Why?
[...] I see is that most calls to snd_pcm_writei are spaced about 50 ms apart. This makes some sense, but I was expecting the calls to be about 42.67 ms apart. However, about every 6th call, the time is just 200 us or so. Why is that?
In theory, when the device is configured for a specific period size, its interrupts (and therefore the application wakeups) will arrive spaced at this interval (modulo any scheduling delays).
However, if you're using the dmix plugin, the period size of your application's device will not necessarily be identical with the period size of the hardware device. To see the actual period size, look into /proc/asound/card?/pcm0p/sub0/hw_params.
Regards, Clemens