> > I found some audio noise problem when I trying to set the sink latency to a lower value. > > here is the alsa dump: > > D/NMAudio ( 1959): Its setup is: > D/NMAudio ( 1959): stream : PLAYBACK > D/NMAudio ( 1959): access : MMAP_INTERLEAVED > D/NMAudio ( 1959): format : S16_LE > D/NMAudio ( 1959): subformat : STD > D/NMAudio ( 1959): channels : 2 > D/NMAudio ( 1959): rate : 22050 > D/NMAudio ( 1959): exact rate : 22050 (22050/1) > D/NMAudio ( 1959): msbits : 16 > D/NMAudio ( 1959): buffer_size : 8192 > D/NMAudio ( 1959): period_size : 2048 > D/NMAudio ( 1959): period_time : 92879 > D/NMAudio ( 1959): tstamp_mode : ENABLE > D/NMAudio ( 1959): period_step : 1 > D/NMAudio ( 1959): avail_min : 7751 > D/NMAudio ( 1959): period_event : 0 > D/NMAudio ( 1959): start_threshold : -1 > D/NMAudio ( 1959): stop_threshold : 1073741824 > D/NMAudio ( 1959): silence_threshold: 0 > D/NMAudio ( 1959): s > > here is the log when problem happened: https://git.kernel.org/cgit/linux/kernel/git/tiwai/sound.git/tree/include/linux/dmaengine.h * @DMA_RESIDUE_GRANULARITY_SEGMENT: Residue is updated after each successfully * completed segment of the transfer (For cyclic transfers this is after each * period). This is typically implemented by having the hardware generate an * interrupt after each transferred segment and then the drivers updates the * outstanding residue by the size of the segment. Another possibility is if * the hardware supports scatter-gather and the segment descriptor has a field * which gets set after the segment has been completed. The driver then counts * the number of segments without the flag set to compute the residue. * @DMA_RESIDUE_GRANULARITY_BURST: Residue is updated after each transferred * burst. This is typically only supported if the hardware has a progress * register of some sort (E.g. a register with the current read/write address * or a register with the amount of bursts/beats/bytes that have been * transferred or still need to be transferred). */ How accurate can you sound card hw_ptr increase ? period size or DMA brust size ? http://mailman.alsa-project.org/pipermail/alsa-devel/2014-September/081501.html you can try Alexander's pcm_avail.c -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.freedesktop.org/archives/pulseaudio-discuss/attachments/20150609/ff54179c/attachment-0001.html>
