I have a general question on dynamic range (DR). Redbook CD offers 16 bit, corresponding to 96dB DR.
According to a more accurate
formula, it is even about ~98dB, and I think strictly speaking, that is referring to the
SNR, rather than the dynamic range. Although in
linear quantisation systems, both refer to more or less the same, in non-linear ones, the dynamic range can be a lot higher if one accepts a varying noise-floor, like the G.711 codec does when mapping 12 bit linear to 8 bit of non-linear PCM.
With dither up to 120dB. High-Res 24 bit audio even 144dB.
Yes, although the term "high resolution" actually already is a stupid marketing term. Being higher "resolved" of what? The visual counterpart of resolution would rather go along with sampling in the case of audio, so higher numbers, given, allow for more bandwidth although any human would require a way better set of ears to make use of it. When it comes to quantisation, nothing is finer "resolved" regardless of the bit-depth, but only the SNR is higher, given proper dither. No stairsteps, they aren't there.
Vinyl, according to different sources up to 70dB and tape machines roughly 65dB.
I'd want to see that on any vinyl, but let's believe that in good optimism. I'd rather opt for tapes or FM-modulated analog audio like the LaserDisc provides it, if it really has to be analog for the ones who don't trust discreet character sets.
So my question would be, why is it not possible (or desirable?) to record the full dynamic range of live music and why is the capacity of the standard CD not taken advantage of?
The sad truth probably is that apparently less and less individuals really want a lot of dynamic range. Even so-called "audiophile" recordings, while often well-produced without a doubt, are rather mediocre in terms of dynamic range. Same partly with movies, where rattling, heavy bass and noise all the time is often confused with high dynamic range, although the opposite is true.
Is the 96dB - 25dB = 71dB difference of capacity minus actual content on CD actually wasted? Not talking about 3dB loudness war abominations or even High-Res. Or am I mixing things up?
The diagnose of being "waste" depends on the desired result, I'd say. Interestingly, it occurs on a technical level as the amount of data is somewhat wasted though if the dynamic range isn't used by the content. Often, 12 bit / sample propably would suffice as well and with nowadays, mostly horribly produced pop music, even 8 bit (properly dithered and noise shaped) would be casting pearls before swine, not to speak of 16, 24 being the definition of absurdity.
Same is true for the sample rate, by the way. If the content never uses frequencies above 16 kHz for example (assuming to start from 0 Hz), then 32 kHz sampling rate would do it as well, taking details such as anti-aliasing filtering aside (which would have to be very steep then, etc.).
If it is a 16bit recording, this is all that's left:
View attachment 283553
Beware of trying to make any point by using Audacity's really lousy rendering of waveforms as this is
not what one will get to hear on any DAC's output. Audacity shows the usual stair-steps without any visual reconstruction which happens in reality. Editors like Adobe Audition (formerly "Cool Edit (Pro)") do this way better and show the mathematical reconstruction of the time- and value-continous waveform.
DR (as in the database) has nothing to do with dynamic range.
While I agree with your posting in general, I disagree with the "nothing", especially given such an emphasis as of course, the DR values in the database do have something to do with dynamic range or at least a sub-set of it depending on the definition (or rather the 'scope'). According to some explanation from the DR TT Meter back in the days, this tool deliberately only takes the loudest parts of tracks and effectively measures the average level to peak ratio in order to prevent giving music with quiet parts somewhere else higher results than they "deserve". Sure, the total (macro) dynamic range is the entire span from quietest to loudest, but the DR meter rather takes the micro dynamics approach.
That is the point, redbook CD has about 30dB more DR then vinyl, but at least in that database the DR of the same recording in both formats is basically the same. Why not make use of the additional capacity?
I might be wrong about this point, but I assume that this is also due to the DR meter telling only some part of the dynamic range, here the average to peak relation. Also, most music neither uses the entire range of "so so vinyl" nor that of 16 bit PCM by far of course. Because of vinyl's (well, at least when used in an analog way which is virtually the only established application) higher noise floor, the macro SNR / dynamic range of a given musical piece will be lower than the PCM's counterpart but since the focus is rather on the average to peak - ratio for that measurement, it doesn't change too much.
You may take a 16 bit PCM file, measure the DR value, convert it to a dithered 8 bit one and measure again.
In general, today we have the "screaming irony" that we surpassed the ability to reproduce sound entirely flawlessly since the introduction of the CD with 44.1 kHz / 16 Bit since 40 years now, being enough forever (at least until evolution gives us better ears and with no frustrating aging, please) but instead of using it, we constantly keep barking up the wrong trees* with "high res audio" here, "lossless audio" there, the last dB of SNR even further below the threshold of hearing, considering lossy formats as inferior (god forbid, a streaming service "only" uses AAC or movies nowadays only provide AC3 or DTS) but then praising the worst one of all - scratchy vinyl - which proves pretty well, how bad quality can actually be without necessarily neglecting the enjoyment of music or entirely masking a good production.
Wrong world and a pity for the CD as its marketing claim "perfect sound forever" was closer to the truth than many realise, especially today where anything other than 2.x MHz DSD or 192 kHz / 32 Bit PCM floating point is pure blasphemy.
* for the ones who read German, I can only highly recommend
pelmazo's blog where he especially disassembled the usual marketing bullshit and misinformation where "data reduction" and "compression" are thrown together and the oh so evil lossy codecs of course are the root cause of our quality misery. Neither, he is too fond of all the voodoo non-sense which is going on and which drowns real information beyong recognition. Also his other posts are extremely enriching.