Takashi Iwai wrote: > At Sun, 24 May 2009 19:26:42 -0700, > Troy Kisky wrote: >> Does >> >> (substream->dma_buffer.bytes) need to equal (snd_pcm_lib_period_bytes(substream) * runtime->periods) ? >> >> When this is not true, it seems like the buffer is not being filled correctly. >> >> >> for testing, this works >> .buffer_bytes_max = 16 * 7 * 512, >> .period_bytes_min = 32, >> .period_bytes_max = 7 * 512, /* This is size of ping + pong buffer*/ >> >> and this doesn't. >> .buffer_bytes_max = 16 * 7 * 512 + 512, >> .period_bytes_min = 32, >> .period_bytes_max = 7 * 512, /* This is size of ping + pong buffer*/ >> >> >> When playing back a sine wave, I can hear breaks. > > Well, there are two misunderstandings here: > > - substream->dma_buffer.bytes doesn't define the actual buffer size. > It's substream->runtime->buffer_size (in frames). The former is the > allocated buffer size which can be larger. > > - The buffer size doesn't have to be aligned to period_size as default, > i.e. it's not always equal with period_size * periods, and periods > isn't always an integer. > > To align the buffer size to period size, call below in the open > callback > snd_pcm_hw_constraint_integer(runtime, SNDRV_PCM_HW_PARAM_PERIODS); > > > HTH, > > Takashi > Yes, that fixed my problem. Thanks you Troy _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
