On Tue, Sep 10, 2019 at 9:18 AM Takashi Iwai tiwai@suse.de wrote:
The value read from snd_pcm_status() should give the accurate pair of the position and the timestamp.
Thanks. IIUC, if I call snd_pcm_status() in that mmap_commit method, get data between e.g. 10 seconds, and divide the increase of status._ptr https://github.com/michaelwu/alsa-lib/blob/afb2fbd0e554e42e51325c3197a176ea9... by increase of status.tstamp, I should get the the most precise available soundcard rate estimate referenced to system time.
You need to check the delay count as well, which compensates the in-flight samples.
I need just the rate at which the soundcard consumes/produces samples, I do not care about time at which the sound is being produced. I do not know exact meaning of the delay field. Is it involved in this calculation? Please is there any exact detailed description of the status fields?
Thanks.
Pavel.