On Wed, 19 Sep 2007 16:17:55 -0700 "Sheng \(Sean\) Liu" <shengl@xxxxxxx> wrote: > 1. The control point here the start threshold, which defines the number of > frames of space/data necessary to start the device automatically. If set to > some value other than zero for playback, it is necessary to prefill the > playback buffer before the device will start. If set to zero, the first data > written to the device (or first attempt to read from a capture stream) will > start the device. > > My question: what does he means on " If set to zero"? Does anyone know which > parameter of which API should be set to zero? I believe this would be snd_pcm_sw_params_set_start_threshold. > 2. You can also start the device explicitly using snd_pcm_start, but this > requires buffer prefilling in the case of the playback stream. If you > attempt to start the stream without doing this, you will get -EPIPE as a > return code, indicating that there is no data waiting to deliver to the > playback hardware buffer. > > My question: Is there anything to be done before calling snd_pcm_start in > the case of capturing stream? If there is, what are they? I use: snd_pcm_open SetUpHwParams () ... /* lots of snd_pcm_hw_params_set ... calls */ SetUpSwParams () ... /* lots of snd_pcm_sw_params_set ... calls */ snd_pcm_prepare snd_pcm_start Best regards, Scott. _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
