Takashi Iwai wrote: > At Wed, 11 Oct 2006 16:00:54 +0100, > James Courtier-Dutton wrote: >> Assaf Hoffman wrote: >>> Hi, >>> Thanks again for clear answers. >>> In case the HW strip the IEC958 frames, where the ALSA stack expect to >>> find the various frame data fields such as perr, valid bit, audio >>> sample, user data and channel status? Is there a data structure the HW >>> should follow when DMAing the striped data to the DRAM buffer? >>> What do you think of such acceleration? Does this saves a significant >>> CPU time processing the ICE958 frames? >>> Many thanks. >>> P.S. >>> I was looking into the ASLA stack and I could find >>> SNDRV_PCM_FMTBIT_IEC958_SUBFRAME_XX only in snd_pcm_hardware structure >>> initialization. I could not see where it is used to tell the ALSA to >>> process the data as IEC958 frames. >>> >> A majority of sound cards strip the frame, and only put the audio >> samples in the DMA buffer. The sound card then stores the valid bits, >> non-audio bit, user data etc. in a separate register on the sound card. >> >> The processing of the IEC958 frames is done in alsa-lib. >> ALSA has two parts, and kernel part, and a user space lib. >> The kernel part does as little as possible, with the user space part >> doing all the format conversion etc. >> >> I have not looked closely, but I don't know if the alsa-lib decodes the >> IEC958 frames or not yet. > > It can. iec958 plugin does encode/decode IEC958 frames. > > > Takashi Does it let the user app set the valid, non-audio etc. bits? ------------------------------------------------------------------------- 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
