On Wed, 21 Nov 2007, Sergei Steshenko wrote: > On Wed, 21 Nov 2007 20:33:39 +0100 > Paolo Saggese <pmsa4-alsa@xxxxxxxx> wrote: > >> Hi everybody, >> >> I have a question for you guys. >> >> (I'm new to this list and hope this is the right place to ask >> and not an FAQ... I've tried to search to see if this question >> had been answered previously, but I have been not able to find >> what I was looking for). >> >> I'm thinking about using a dedicated (fanless, diskless, etc) >> PC as a digital source for my hi-end Hi-Fi system. >> >> Of course I plan to use the PC only to provide a "bitperfect" >> (exact copy of the original media, normally CD) digital stream >> to an external DAC. >> >> As you probably know better than me, the one major known problem >> when you strive for the highest possible quality in digital audio >> reproduction is jitter... and the best (if not only) way to really >> minimize it is to use a good, clean and stable clock close to the >> DAC chip, slaving everything else to that one. The clock jitter tends to be in the ppm range. This means that the frequency jitter is very low (if I believe the ppm then at the level of -120dB) which is completely inaudible. My cheap Transit card reliably gives me noise levels of the order of -90db below the level of the signal, again inaudible. >> >> Thus, what I would need to do would be to "slave" the sound card >> SPDIF output clock to the external DAC clock i.e. to make this one >> become the "master clock" for the whole digital audio stream. SPDIF is a digital output stream. Its "clock" is irelevant. The clock on the machine that converts that stream to analog is the important one. >> >> AFAIK, one possible way to do this is to set up a "fake" SPDIF >> output from the external DAC and connect it to an input of the >> sound card whose SPDIF output goes to the DAC for conversion. ???? >> >> Of course the sound card must be able to "slave" (synchronize) >> its SPDIF output clock with the one coming from its SPDIF input. >> >> (BTW: are there other -perhaps easier and/or better- ways to do >> what I would like to do?) >> >> >> Thus, I would need a sound card which must be: >> >> * cabable of "bitperfect" (pass through) operation at CD standard >> 16bit/44.1KHz (as well as, possibly, also at higher resolutions and >> sample rates such as 16/48, 24/48, 24/96 and 24/192). bit perfect digitial operation is trivial Almost anything can do that. Computers do it at GHz frequencies so 96KHZ is completely and totally trivial. The only crucial thing is the Digital to analog converter. >> >> * capable of "slaving" its SPDIF output clock to an external one, >> such as the one reconstructed from its SPDIF input. >> >> ....last but not least, of course all of this must be done on Linux, >> thus the sound card must be fully supported by ALSA! 8-) >> >> Well, yet another requirement is... that it should possibly (and >> hopefully) not cost me a fortune! $-) >> >> > Extracting data digitally from CD is unrelated to soundcard. > > Perform web search for 'cdparanoia'. > > In fact, if you want reliable sound, first transfer data from _all_ your > audio CDs to HD and then play it from there. > > Regarding soundcard and syncrhonization - M-Audio Revolution 7.1, and > quite possibly M-Audio Revolution allow you to use external clock > source. > > I have never used SPDIFF myself though. ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Alsa-user mailing list Alsa-user@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/alsa-user
