Opening a stream with a framesPerBuffer of 0 causes a buffer underrun and a stutter

[Darfk]

portaudio/examples/stereoSine.go

Line 30 in bb74aa4

s.Stream, err = portaudio.OpenDefaultStream(0, 2, sampleRate, 0, s.processAudio)

I noticed in your example I receive many messages about a underrun accompanied with a jarring stutter, I simply changed the framesPerBuffer parameter to 1024 and no longer received these messages.

Terminal output with original framesPerBuffer amount:

% go run main.go
ALSA lib pcm_dmix.c:1089:(snd_pcm_dmix_open) unable to open slave
ALSA lib pcm.c:2642:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.rear
ALSA lib pcm.c:2642:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.center_lfe
ALSA lib pcm.c:2642:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.side
ALSA lib pcm_route.c:869:(find_matching_chmap) Found no matching channel map
ALSA lib pcm_oss.c:377:(_snd_pcm_oss_open) Unknown field port
ALSA lib pcm_oss.c:377:(_snd_pcm_oss_open) Unknown field port
ALSA lib pcm_usb_stream.c:486:(_snd_pcm_usb_stream_open) Invalid type for card
ALSA lib pcm_usb_stream.c:486:(_snd_pcm_usb_stream_open) Invalid type for card
ALSA lib pcm_dmix.c:1089:(snd_pcm_dmix_open) unable to open slave
ALSA lib pcm.c:8526:(snd_pcm_recover) underrun occurred
ALSA lib pcm.c:8526:(snd_pcm_recover) underrun occurred
ALSA lib pcm.c:8526:(snd_pcm_recover) underrun occurred
ALSA lib pcm.c:8526:(snd_pcm_recover) underrun occurred
ALSA lib pcm.c:8526:(snd_pcm_recover) underrun occurred
ALSA lib pcm.c:8526:(snd_pcm_recover) underrun occurred
ALSA lib pcm.c:8526:(snd_pcm_recover) underrun occurred
ALSA lib pcm.c:8526:(snd_pcm_recover) underrun occurred
ALSA lib pcm.c:8526:(snd_pcm_recover) underrun occurred
ALSA lib pcm.c:8526:(snd_pcm_recover) underrun occurred
ALSA lib pcm.c:8526:(snd_pcm_recover) underrun occurred
ALSA lib pcm.c:8526:(snd_pcm_recover) underrun occurred
ALSA lib pcm.c:8526:(snd_pcm_recover) underrun occurred
ALSA lib pcm.c:8526:(snd_pcm_recover) underrun occurred

[gordonklaus]

I'm not sure what the real issue here is. Passing zero as framesPerBuffer is valid (although it would be more explicit to pass FramesPerBufferUnspecified).

I assume PortAudio (or ALSA) would then choose a buffer size appropriate to achieve the desired latency. Perhaps your latency settings are unreasonably low? I'm not familiar with how to configure ALSA.

Sorry I can't be of more help. I recommend asking on the mailing list.