24bit vs 16bit, the myth exploded! - Page 6

No, as I understand it, the 24bit 192kFs/s standard was decided upon because it was way beyond what was ever likely to be needed. If you create a standard which is so ridiculously beyond what humans are capable of perceiving that will hopefully result in this format never going out of date or requiring a new format incompatible with old formats. Bare in mind this format was agreed before any converters existed which were capable of 192kFs/s.

ADAM, Yamaha and SPL did not invent the format, as far as I know the first to support this format were DigiDesign. I can't remember off the top of my head the name or composition of the standards organization responsible. I should also mention, that professionally we've been using higher than 16bit for almost 20 years, although it's only relatively recently that it's been called Hi-Res and there has been a consumer demand for it. Now there is a market, I cannot blame Yamaha or ADAM for taking advantage of it, even if the demand is almost entirely superfluous for the consumer. If you are talking about professional studio monitors, then as mentioned previously 24bit is useful for recording and mixing, it's as a playback consumer format that 24bit is irrelevant.

G

Yes, those Sennheiser mics look interesting. I haven't had chance to see them yet. They were only released last year and have only become available in the last few months. In fact, AFAIK some of the 8000 series models have still not been released yet. I presume they are designed to replace the MKH40 series, which I have used and which have a maximum frequency of 20kHz, good mics though.

To be honest I'm looking forward to having a play with the 8040 and seeing exactly what their frequency response is. At the moment though I don't have access to one and I don't know anyone who has done more than just seen them at a trade show. Again though, all but the last few kHz of their (quoted) maximum frequency response (50kHz) can be encoded at 96kFs/s. They go nowhere near the 96kHz of 192kFs/s.

As they are so new though, they cannot account for differences that consumers think they hear with existing 192kFs/s recordings.

As I said before, there are a few mics which go up to 40kHz (Schoeps for example) and it looks like there is a new one which might go up to 50kHz. All the most commonly used studio mics though, max out at 20kHz or lower.

You can try nit-picking and finding any scrap of information which may provide some proof that some relatively insignificant detail of what I have stated is disputable. But the main substance of what I have stated is correct, namely: 24bit is a complete waste of time for the consumer and so is 192kFs/s.

G

Theoretically there is good a reason why 96kFs/s could sound better than 44.1kFs/s. The anti-alias filters at 44.1k have to be very steep (to stay out of the hearing range) and it's relatively difficult and expensive to create good steep brick wall filters without noticeable artifacts. The anti-alias filters are much smoother (less steep) with 96kFs/s and so are much easier and cheaper to implement without noticeable artifacts. So in theory it is potentially possible that a difference could be perceived. There is some anecdotal evidence to support this potential difference but so far as I'm aware no one has yet managed to get a significant result in DBT. Most good studios use good quality ADCs though, so in most commercial releases it is extremely unlikely (but not provably impossible!) that the anti-alias filter at 44.1kFs/s is going to have any noticeable artifacts which could be improved by the smoother filters in 96kFs/s.

Again though, even if there is a perceivable difference with 96kFs/s it is not related to data resolution. I conducted my own tests in 2002 with both 96kHz and 192kFs/s and neither I nor any of my colleagues could tell a difference, except that my hard disk space seemed to get eaten up at an alarming rate and my processing ability was decimated!

These days, when recording for TV/Film I use 24bit-48kFs/s and then dither down to 16bit. For CD I generally use 24bit - 44.1kFs/s or if I'm not convinced with the quality of the ADC, I might use 24bit-88.2kFs/s then dither back to 16bit-44.1k. Beyond for testing purposes, I don't bother with 192kFs/s at all.

G

Filtering has to be involved, there is no choice or option. The Nyquist limit for 44.1kFs/s is 22,050Hz anything above this frequency must be removed otherwise the sampling (or re-sampling) process either fails entirely or results in alias images which cause serious artifacts. It's not hardware filtering, just as it isn't hardware filtering in ADCs but it must brick wall filter, this is a basic "law" of digital audio.

No they don't, there is no equivalent in audio to "large poster format". With bit depth it would mean the audiophile listening at a volume which would at the least make them permanently deaf and in sample rate it would mean pitch shifting the highest frequencies in the music down by more than 2 octaves, while leaving the lower frequencies unaltered (otherwise they would be too low to be heard!).

G

"Doing it right" is a contentious issue. I know that a lot of design and processing power is thrown at "doing it right" in high end ADCs. What I do know is that it's very difficult to avoid artifacts with a steep brickwall filter. But brickwall filters aren't all created equal, there are quite a number of different ways an anti-alias filter can be implemented. I posted a link earlier in this thread to a really good paper on digital filters. The exact implementation of what is done by Wavelab or indeed inside ADCs with regards to brickwall filters is beyond my knowledge and to an extent probably considered by some to be a trade secret. To be honest Wavelab is not generally used in commercial studios and I don't believe is considered "professional" quality more of a pro-sumer product. I don't know what dithering algorithms are used by Wavelab either.

Sorry, I haven't really answered your question. I would like to run the test file "Dragon boat" myself to find out what is really going on but my system is currently configured for a project I'm working on and I won't want to mess with it until I'm finished on the 7th April.

G

Exactly, to hear the accuracy at very low levels in 24bit audio you would have to turn your amp up so high that when a sound came in near the high end of the dynamic range it would probably put the listener in a coma (no joke)!! But as I've already mentioned there is no equipment out there that can actually resolve 24bit audio. And yes, your analogy with using a higher sample rate would mean at 192kFs/s three quarters of the colours used would be beyond the light frequencies visible to a human being.

In other words, a correct analogy would be a poster which included colours so bright that looking at them would cause permanent blindness and where three quarters of the colours used could only be seen or appreciated by bees!! Unless of course you are a 'visiophile' in which case those ultra-violet colours and x-rays definitely improves the percievable quality of the image

G