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?

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

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

_PCM_INFO_DOUBLE /* double buffering needed for PCM start/stop */ snd_pcm_hw_params_is_double()

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

-- Eliot