2010-07-13 07:08, Raymond Yau skrev: > 2010/7/10 David Henningsson <launchpad.web@xxxxxxxxxxxxxx> > >>> PA developer often complain the driver did not provide accurate playback >>> position by the pcm_pointer callback >>> >>> Did the pulse_pointer callback also provide accurate position of the >> pulse >>> device ? >> >> Yes, but it provides the pointer to the fake ring buffer (the alsa-lib >> plugin system expects that all pcm plugins are ring buffers, which seems >> to me like a design flaw). >> > This mean that pulse_pointer jump suddenly when PA wake up from sleep and > write audio to sound card until the ring buffer is empty, Those "0 bytes in > queue " message is the result of PA server flush the ring buffer. > Did alsa-lib regard this condition as underrun, since the application > pointer and hardware pointer of the pulse device seem at the same point ? No, I don't think so. An underrun message is a special message sent from the PA server and should not be directly related to the fake ring buffer, and it is that message now being ignored (configurable, thanks to Takashi). My first patch (http://git.alsa-project.org/?p=alsa-plugins.git;a=commit;h=1675414) fixes so that if pa_stream_writeable_size returns a value greater than the ring buffer's size, it only reports size-1 bytes available, which means that the alsa app won't see it as the application pointer and hw pointer being the same. > Is this the reason why alsa-time-test.c fail on the pulse device ? No idea, haven't looked further into that application. // David _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
