Alan Stern wrote: > On Tue, 4 Sep 2012, Jassi Brar wrote: >>> Second, people involved in real-time programming (such as audio or >>> video) generally want to keep latency to a minimum. >> >> If we progress the h/w pointer of ALSA ring buffer at URB completion >> (and not at URB submission), > > I don't understand this comment. As far as I can tell, the relevant > pointer already is being advanced during URB completion.
It's advanced directly after submission. The queued data is double- buffered because the USB API lacks the ability to scatter/gather from a coherent buffer. >> this shouldn't affect the latency. How would this make any difference? The time between the application writing samples to the buffer and the samples actually being played by the device would not change. Regards, Clemens -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
