[alsa-devel] Understanding SND_PCM_INFO_ [BATCH, BLOCK_TRANSFER, DOUBLE]

Eliot Blennerhassett linux at audioscience.com
Wed Feb 17 08:35:36 CET 2010

I've been looking at these info flags, and whether they cause the driver
to be accessed any differently by the upper layers.
So far I can find hardly any examples where they are used in any
significant way - what am I missing if anything?

double buffering
skips the check enabled by XRUN_DEBUG_JIFFIESCHECK
alsa-lib returns it in snd_pcm_hw_params_is_batch()

/* hardware transfer block of samples */
translated by pcm_oss.c into ~DSP_CAP_REALTIME
lib: snd_pcm_hw_params_is_block_transfer()

/* double buffering needed for PCM start/stop */

I don't see any of these functions called by aplay...


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