Hi Cliff, On Wed, 2008-01-02 at 06:26 +0000, cailinhua wrote:> I want to enable dmix for our sound card.Unfortunately for some reason the sound card driver don't support > 'mmap' way,it only support 'copy' callback to copy data from upper level to DMA.So ,I think maybe I can modify > the alsa-lib dmix source code to let it use 'copy' way to send data to the driver. Is it possible？> Could you please give me some ideas? I don't know how difficult it would be to change alsa-lib's dmixsources, but my suggestion - in general - would be to alter the driverof your sound card to use the "intermediate buffer" technique (usingpcm-indirect.h): Setup a buffer in RAM, which can be mmap'ed byapplications and copy the contents of this buffer to the hardware in abackground process for example.(See Takashi's "Writing an ALSA Driver" guide.) I know, perhaps this is not the easiest solution ... and it's not a"direct" answer to your question - just a thought. Joachim _______________________________________________Alsa-devel mailing listAlsa-devel@xxxxxxxxxxxxxxxxxxxx://mailman.alsa-project.org/mailman/listinfo/alsa-devel
