audioengr;324281 Wrote: > I see. Then the clock rate that you want must be provided to the > Transporter as the correct word-clock BEFORE you try to decode the data > stream. > > I though that you meant that the file frequency alone would determine > the clock-rate. > > What happens if you provide 96kHz word-clock and the file that you are > trying to play is 44.1? >
Yes, the file (WAV, FLAC, whatever) contains in its headers the information that _normally_ Transporter would use to select which of its internal oscillators to use. This information is also indicated (passed through, you might say) in the s/pdif channel status bits. When word clock is enabled, Transporter plays at the word clock input frequency no matter what the source file indicates that the sample rate is supposed to be. However, the information from the source file is still passed through untouched to the s/pdif channel status bits. So to rephrase (I think) your question, the problem is how does the Pace-Car know what sample rate to send the Transporter if it has yet to receive those s/pdif channel status bits? Well, it can't know until it gets them. So if you're playing along at 44.1 and all of a sudden some 96KHz content comes along, what will happen is that you'll have to switch your internal clock source as soon as you see 96KHz in the channel status. At that point there would be some brief drop-out of the signal while the PLL on Transporter's side resycns. I forget how fast that is but I think it's pretty quick - 10ms or something. Add to that perhaps some time for the s/pdif receiver to resync, which usually takes a bit longer. I don't know how noticeable it might be. I've never had an external clock source on-hand that could change its output word clock depending on the s/pdif information. What I do know is that Transporter will have no problem changing clock rates quickly - the way the PLL works inherently creates a clean transition. One thing that is fun to try, if you have a function generator, is to feed that directly into the word clock input and then turn the knob to hear what it does. Between about 20KHz and 100Khz it should have no problem. Above or below that range it will break in obvious ways. -- seanadams ------------------------------------------------------------------------ seanadams's Profile: http://forums.slimdevices.com/member.php?userid=3 View this thread: http://forums.slimdevices.com/showthread.php?t=50273 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/lists/listinfo/audiophiles
