thank you very much. but, （1）what is the relationship between DMA buffer size and the boundary size？does the variable buffer_size equal to DMA size？ (2)how the pos>buffer_size will happen in the interface snd_pcm_update_hw_ptr0()？ the variable pos is in the range of DMA_size，it can not bigger than the buffer_size.it blocked me.

thanks a lot.

在 2012-12-10 00:23:55, Clemens Ladisch clemens@ladisch.de写道: l9jj wrote:

can anyone help me to figure out the concepts between period_size ,buffer_size and boundary size? n * period_size = buffer_size?

Yes. On many devices, n is not required to be an integer.

m * buffer_size = boundary_size?

Yes, where m is very big. In applications, the actual value of the boundary size does not matter (except as a special value for some sw params).

and how the dma buffer mapped to the alsa buffer?

The DMA buffer _is_ the ALSA buffer.

Regards, Clemens _______________________________________________ Alsa-devel mailing list Alsa-devel@alsa-project.org http://mailman.alsa-project.org/mailman/listinfo/alsa-devel

l9jj@163.com

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