Florin Andrei wrote: > [...] > But with the PC, once the digital coaxial carrier comes up, it's always > ProLogic and 2.1, never Dolby Digital and 5.1 > > So there are a few possibilities here: > 1. I am really dumb. > 2. I just had a long string of bad luck and just used bad sound cards > 3. There's something wrong with the amplifier 4. software patents SPDIF was designed for stereo, so it has only the bandwidth for two channels of data at 48 kHz. (There are extensions for higher sample rates by increasing the clock, but there are never more than two channels.) To transport more than two channels over SPDIF, the audio data has to be compressed so that it fits into the bandwidth that two uncompressed channels would use. There are two common codecs, Dolby/AC-3 and DTS; both are heavily patented. Any sound card that wants to encode multichannel audio for transport over SPDIF has to include an encoder license. Very few do (the Windows drivers for CMI8768+/8770/8788 and some X-Fi cards come with encoders). Without encoder, 5.1 playback works only when the source data has already been encoded previously (e.g., on a DVD). AFAIK there is no Linux distribution that ships with an encoder, but you can download and install an AC-3 encoder manually (see <http://www.alsa-project.org/main/index.php/A52_plugin>). HTH Clemens _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx http://lists.linuxaudio.org/mailman/listinfo/linux-audio-user
