I would like to be able to make small adjustments the playback clock rate of a PCM device as it is playing in order to accurately synchronize music playback across several computers. Looking at the kernel source, this functionality has been previously implemented in both the aloop driver and ST's uniperif driver where the clock rate adjustment was exposed to the user space as a control element.
Although the control interface can be used to communicate this information, the naming and properties of the clock adjustment controls don't appear to be standardized or documented and I don't see anything related to clock rate adjustment in Documentation/sound/alsa/ControlNames.txt.
In order to make a standardized interface, do you think it makes more sense to standardize on a clock rate adjustment control or introduce a new interface other than the control interface because the control interface is only for mixer controls rather than arbitrary runtime changes to the driver?
Regards, Chas