Let me first describe the concepts I understand and then I might be able to ask some questions that make sense.
Data is broken up on an S/PDIF stream into 64-bit frames grouped into 192-frame blocks (1536-byte blocks). Assuming I can properly decode all of the status bits in each frame, blah blah blah, I can end up with either a PCM stream or, let's say, a compressed-audio stream consisting of AC-3 to DTS bitstream data. (For example, I might be recording the output of a DVD player.) Once I have the specific information about what to do with the bitstream (either record it directly to file if it's PCM or run it through a decoder if it's AC-3 or DTS), I'm golden. The problem somes in my trying to figure out the proper way to open a device and record the output so I can do whatever it is I need to do. So, from the beginning, I know I'll need to open a device. Normally, I'd use snd_pcm_open() on "hw:0,0" (for example) but I'm not sure that's even appropriate here. I want to be opening the decive for S/PDIF capture, not necessarily "PCM" capture. Also, once the device is open I don't know of any real hardware parameters I might want to set. Maybe I should be setting the buffer/period parameters but the rate at which I receive data from the interface is not necessarily constant. I'll assume I want to read in blocks of 1536 bytes-at-a-time as long as ALSA is properly synchronizing to the S/PDIF frame and giving me aligned blocks. Is this an assumption I can make? Some pointers on where to start learning about all of this would be great. After reading lots of documents I could currently find and trying to read code in existing programs I don't see anything that answers my questions so I know what I'm doing. Thanks! Paul Braman ------------------------------------------------------------------------------ Nokia and AT&T present the 2010 Calling All Innovators-North America contest Create new apps & games for the Nokia N8 for consumers in U.S. and Canada $10 million total in prizes - $4M cash, 500 devices, nearly $6M in marketing Develop with Nokia Qt SDK, Web Runtime, or Java and Publish to Ovi Store http://p.sf.net/sfu/nokia-dev2dev _______________________________________________ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
