Clemens Ladisch wrote: > Timur Tabi wrote: >> It turns out that ALSA (when using mplayer to play a divx video file via OSS >> emulation) is rapidly sending back-to-back SNDRV_PCM_TRIGGER_STOP and >> SNDRV_PCM_TRIGGER_START commands. Why would it do that? > > To recover from underruns. I've added some function traces to ALSA, and apparently ALSA is telling the driver to STOP when the driver calls snd_pcm_period_elapsed(). Here's a log: snd_pcm_period_elapsed snd_pcm_update_hw_ptr_interrupt:232 <- last line of this function PERIOD <- printk in the driver's ISR snd_pcm_period_elapsed snd_pcm_update_hw_ptr_interrupt:232 snd_pcm_update_hw_ptr_post xrun snd_pcm_stop snd_pcm_action snd_pcm_action_single snd_pcm_do_stop STOP 279 <- command to stop after sub-buffer #279, which is at the end of the period Unfortunately, very little of the code in sound/core/pcm???.c is documented, so I'm having a hard time figuring out what's going on. Why is ALSA telling the driver to stop during a period interrupt? -- Timur Tabi Linux kernel developer at Freescale _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
