Re: [Alsa-devel] midi timing fixes/questions

[Jack Moffitt]

> There is still the same amount of drift though.  

I have calculated the drift:

the interval in microseconds is calculated by
snd_pcm_timer_resolution_chage() like so:

1000000000 * period / rate

and truncated to an integer.  for a period of 32 and a rate of 44100,
this means we are throwing away .58276643 microseconds per period.

There are 1378.125 periods per second, which means we lose about 803
microseconds per second.

Over a five minute song, we lose about 240 milliseconds, which is _very_
noticeable.  Every minute we'll lose 48ms.

With a period of 128, the drift is only 38ms over five minutes, or 6.8ms
a minute.

jack.

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