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Originally Posted by Bob Pariseau 
The reality is that people making high quality recordings -- made with maximal care and attention to detail -- are more likely to author those for high bit rate rather than CD rate. The actual frequency and dynamic range in the RESULT might not be better than if they had stuck to CD rate, but odds are they feel more comfortable working at the higher rate.
The reality is that people making high quality recordings -- made with maximal care and attention to detail -- are more likely to author those for high bit rate rather than CD rate. The actual frequency and dynamic range in the RESULT might not be better than if they had stuck to CD rate, but odds are they feel more comfortable working at the higher rate.
If I knew another version had used more care, technique, better equipment, etc. during mastering I would chose it virtually regardless of format. But comparing differently mastered sources is not what the article deals with:
"This paper presented listeners with a choice between high-rate DVD-A/SACD content, chosen by high-definition audio advocates to show off high-def's superiority, and that same content resampled on the spot down to 16-bit / 44.1kHz Compact Disc rate."
The same content resampled on the spot - and even without dithering (which I suspect would show up at the very end of a reverb tail or fade out when listening at very high volume levels via headphones).
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Next the sampling rate: Digital audio gets "processed". Perhaps quite a lot. (Such processing is not necessarily a bad thing!) Even though 44.1KHz may be perfectly adequate to carry the desired end result in frequency range, you have to be very careful when processing that digital audio data stream to keep from introducing artifacts which can look a lot like the "aliasing" that happens if you try to force too high frequency of content audio into that 44.1KHz. Aliasing doesn't affect just the frequencies that are too high for the sampling rate. It affects ALL THE LOWER frequencies too. So the audio engineers need to be sure they've pre-filtered out the high stuff before digitizing, or the result WILL be screwed up.
Now using a higher sampling rate means you can use a higher filter (as if the human ear could really hear those higher frequencies), but that's not where I'm going. Where I'm going is that making digital audio processing math work at lower sampling rates is tricky stuff! Operating at a higher sampling rate takes more processor power, but you are less likely to trip over a goof in the algorithms that introduces aliasing-like artifacts.
So these are two, good arguments for doing the audio engineering at high bit rate.
Now using a higher sampling rate means you can use a higher filter (as if the human ear could really hear those higher frequencies), but that's not where I'm going. Where I'm going is that making digital audio processing math work at lower sampling rates is tricky stuff! Operating at a higher sampling rate takes more processor power, but you are less likely to trip over a goof in the algorithms that introduces aliasing-like artifacts.
So these are two, good arguments for doing the audio engineering at high bit rate.
The focus of the article as I view it is in listing to a finished product, sans processing, as an audiophile might - the only processing would be an analog volume control. Yes, forcing "too high frequency of content audio into that 44.1KHz" will indeed cause aliasing artifacts, but is there an ADC in common use that doesn't properly handle this? And when it comes to signal processing the math is known and techniques of upsampling, oversampling, etc. are generally properly applied. I agree that if you want to later digitally process the material a higher bit rate is advantageous for the same reasons it is now common place during recording, processing and mastering.
All things being equal there may be some advantage to SACD/DVD_audio vs. CD regardless of bit rate, and that is whether or not those formats have adequate error correction, such as a data CD might, providing for 100% reliable data transfer, which a Redbook CD doesn't (if you rip a CD multiple times, or on different equipment, are the files all identical?). Although this is not an issue raised in the article - it's focused on downloads.
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Of course if just do that willy-nilly, without regard to whether you are carrying ultrasonics along to the final result or any of the rest of the litany of problems he's worrying about, then sure the end result is not "best".
But operating at lower bit rate comes with its own pitfalls! Those algorithmic artifacts for example.
So here's my take: You can't assume a recording is good simply because it is delivered as 192KHz 24-bit.
But you also can't assume it is bad!
But operating at lower bit rate comes with its own pitfalls! Those algorithmic artifacts for example.
So here's my take: You can't assume a recording is good simply because it is delivered as 192KHz 24-bit.
But you also can't assume it is bad!
Granted. But if (under the conditions as presented) the higher bit rate file contains ultrasonic information and your delivery chain cannot either properly reproduce it or filter it out then there a good chance that it will sound worse than the lower bit rate file. And, as I stated in a previous post, the 192kHz example file, which should be silent, does create audible artifacts through one of my audio chains.
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The proof is simple: A 192KHz 24-bit data stream can contain A BIT-PERFECT IMAGE of a 44.1KHz 16-bit data stream. So who's to say it doesn't?
Q.E.D.
Q.E.D.
Is this true? Clearly true with a 16bit/48kHz file (evenly divisible), but with a 44.1kHz file the resampling isn't as straightforward.
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It all comes down to how much care was taken in the recording and audio engineering process. There is nothing INHERENTLY bad about 192KHz 24-bit.
By the way, those same, digital audio processing gotchas come into play in the home theater gear that's trying to render the audio track.
By the way, those same, digital audio processing gotchas come into play in the home theater gear that's trying to render the audio track.
Agreed. And is nothing inherently wrong with any file format that accomplishes its objective. And if you have gear that can properly handle ultrasonics all the better - but I doubt, under the conditions of the article, that it will sound any better, will be a slower download, and take up more space; and require more power - if your gear doesn't filter the ultrasonics out you will need to amplify the stuff you can't hear as well as that that you can (and maybe your overhead and transients will be negatively affected).
Chris
