Re: Fw: writing audiowerk driver (philips saa7146a), some questions

["Martijn Sipkema" <msipkema@sipkema-digital.com>]

> there is a runtime instance for a pcm stream, and this holds the
> informaton such as the current rate, channels, formats, etc.
> there is no pitch parameter implemented in alsa, but this can be added
> easily into the runtime instance, if inevitablly necessary.

i don't think the audiowerk is the only card capable of varipitch, though
most cards don't support it, but it is a nice feature and since alsa is
supposed to be advanced... :)

> alsa pcm engine invokes a timer interrupt to update the "tick", and
> this tick is determined using the rate of the runtime instance.
> if you change the rate value dynamically during playback, then the
> tick interrupt will be wrongly scheduled, and leads to wrong detection
> of under/overrun.

shouldn't the driver detect under/overrun? would a soundcard with a
bad dac (as in not accurate) also cause problems?


--martijn






_______________________________________________________________

Don't miss the 2002 Sprint PCS Application Developer's Conference
August 25-28 in Las Vegas -- http://devcon.sprintpcs.com/adp/index.cfm