On Mon, 25 Oct 2010 10:45:10 -0400 Paul Braman <bramankp@xxxxxxxxx> wrote: > Interesting, but I see a couple of idiological problems with this > approach. > > "dat" implies reading 32-bit frames at a rate of 48KHz. That's all > fine and good but an S/PDIF bitstream is going to be pumping data > faster than that rate. Assuming the embedded audio is 48KHz, 16-bit, > stereo then each frame of raw 32-bit PCM is encoded within a 64-bit > S/PDIF frame. It's as if "arecord" is told to set up to read at only > half the speed it needs to be reading. I'd suspect xrun conditions to > cause the noise. I'm certainly no expert but I don't think it works quite like that. Taken from http://ac3filter.net/guides/ac3filter_spdif... "Since compressed data is transmitted in place of PCM data, the bitrate of the compressed stream must exactly match uncompressed stereo 16-bit PCM bitrate. As a rule, compressed stream (even a multi-channel one) having a lower bitrate, compressed stream must be padded with zeros to match PCM bitrate." It goes on to say that DTS can be converted to use 14 bits instead of 16 to lessen the harsh noise you get when compressed data is mistaken for PCM. When you try to record from S/PDIF with arecord, it only allows S16_LE and S32_LE and I'm pretty sure I tried both. James ------------------------------------------------------------------------------ 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@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/alsa-user
