On Fri, 04 Dec 2015 01:32:41 +0100, Chas Leichner wrote: > > 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. Right, the document hasn't been updated much, and it doesn't mean to stop you inventing a new one. Just propose the de facto standard. > 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? It's not clear what kind of interface you're referring to. Is the new IFACE_XXX of kctl element, or a new API or whatever? IMO, we can keep using the alsa ctl API, but yes, we can standardize the control name. The IFACE_* can be set to IFACE_PCM, for example, if it's dedicated to a certain stream. Or it can be IFACE_CARD if it's global to all. In both cases, it won't appear in the mixer list, at least. thanks, Takashi _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
