2010/2/21 Kai Vehmanen kvehmanen@eca.cx
Hi,
On Mon, 15 Feb 2010, Raymond Yau wrote:
Even using a high resolution timer , the application still cannot achieve
latency better than the configured period size
For USB case , the driver cannot give accurate hw pointer position , hw pointer increase in steps for the current implementation, (i.e. the graph is
... but that's a real hardware limitation for the USB-driver, right? And even in the USB case, hw pointer is incremented in steps of URB transfer size, so even in this case, latency of a highres timer based application is not limited by the set period-size.
Of course, there is no ALSA API to query the burst size (e.g. the granularity of hw_ptr updates), which is a real problem for generic apps (that are not hardcoded to work with just one ALSA driver).
The burst size is less than or equal to the minimum period size