adamdea;655913 Wrote: > e) although analog filters would have a job doing this without phase and > all sorts of other problems, most of the work can now be done digitally > by purely mathemetical proceesses which will not vary with age, > temperature conditions or anything else and can operate with vastly > more than 16 bits precision even if the recorded samples are only at > 16 bits. Great post, adamdea. You have very eloquently presented the points that I feared I might have to try and put across, so I am relieved of that task. However, I do have one nitpick regarding the above statement...
Digital filtering has probably come on from when I last investigated it, but my understanding is that filtering per se is a mathematical treatment of the signal. Whether you implement a filter in hardware (analogue) or software (digital), you end up with the same artefacts predicted by the mathematical model, viz. phase anomalies in the passband (and the steeper the cutoff, the worse those anomalies). In other words, if you implement a brick-wall filter at 22kHz, you WILL get phase errors below 20kHz, regardless of whether the filter is analogue or digital. That's why oversampling is useful in both the A/D and D/A processes. But there remains the issue that even if you record at high sample rates, when you resample down to 44.1 for final delivery you have to put in place that 22kHz brick-wall filter to avoid aliasing. This is the one aspect of Redbook that I might conceivably be persuaded is worth eliminating by increasing the sample rate of the delivery format. That said, there is little evidence that even quite serious phase errors in the top octave are actually audible, so I don't think it matters in practice. I'm still 95% certain that 16/44.1 is good enough. -- cliveb Transporter -> ATC SCM100A ------------------------------------------------------------------------ cliveb's Profile: http://forums.slimdevices.com/member.php?userid=348 View this thread: http://forums.slimdevices.com/showthread.php?t=89733 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/mailman/listinfo/audiophiles
