[alsa-devel] Is there a way to figure out if the clocks of two snd_pcm_t's deviate? (snd_pcm_info_get_sync?)

Heya!

I am looking for a way to find out whether the clocks of two snd_pcm_t's are perfectly in sync and don't deviate (or only deviate by a constant phase).

i.e. for real duplex devices that use the same crystal for input and output this should tell me "Yes" for the playback snd_pcm_t tested against the recording snd_pcm_t; and for all other, unrelated audio devices it should return "No".

I found snd_pcm_info_get_sync() in the docs, but its documentation is a bit terse, so I am wondering if this might be what I want. Is it?

Does this (untested) code snippet do what I hope it does?

<snip> snd_pcm_info(a, info_a); snd_pcm_info(b, info_b); in_sync = memcmp(&snd_pcm_info_get_sync(info_a), &snd_pcm_info_get_sync(info_b)) == 0; </snip>

Thanks,

Lennart