seanadams;324445 Wrote: > 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.
Okay, I think I understand. My Pace-Car does not rely on the channel status bits to decode the sample-rate because it must determine this for an I2S input bus also. This means that I must preselect the word-clock output frequency probably with a switch or by changing the cable to another connector. Steve N. -- audioengr ------------------------------------------------------------------------ audioengr's Profile: http://forums.slimdevices.com/member.php?userid=8041 View this thread: http://forums.slimdevices.com/showthread.php?t=50273 _______________________________________________ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
