Thank you for your reply. Please let me clarify. What you say is that my device can deliver a raw ICE958 data from the capture channel to the DMA buffer and the ALSA stack will know how to deal with it? No need for the device to strip down the payload and only then transfer it to the DMA buffer? In case the sound card can strip down the IEC958 frames into raw sound data + ch status + user data, how would the ALSA stack expect the data? Is there an API for that? Thanks again. -----Original Message----- From: James Courtier-Dutton [mailto:James@xxxxxxxxxxxxxx] Sent: Wednesday, October 11, 2006 3:54 PM To: Assaf Hoffman Cc: alsa-devel@xxxxxxxxxxxxxxxxxxxxx; Rita Shtern Subject: Re: ALSA snd_xferi_t buffer arrangment Assaf Hoffman wrote: > Hi, > > I'm mew to sound and ALSA. > > My project deals with PCM in standard (I2S) mode and IEC958 (SPDIF) > mode. > > Can anyone tell me how the ALSA stack expects to "see" the data received > form the sound device? I mean, what is the format of the data DMA'ed > from the sound device to DRAM that the ALSA stack expects? > > Is this raw sound data? SPDIF frame includes non sound data as well. > Does the sound card HW strip the sound payload from the IEC958 frame to > deliver the raw sound data to the ALSA buffer? > > Please shed some light... > > Many thanks. > > ALSA can deal with all the different formats that the sound device might deliver. The low level sound driver simply tells the upper layers what formats are available. ALSA then handles those formats and all format conversion required to reach the user space application. It depends what your device does as to which format ALSA will see. James ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/alsa-devel
