…BC people asked:
This video is about the recent rise of audio interfaces that can record directly in 32-bit IEEE float instead of the standard 16-bit integer audio [or high-end-audio-production 24-bit integer].
This is the best video I know about the subject, talking about the Zoom UAC-232 and how it probably works.
https://www.youtube.com/watch?v=s0g0XXm9XJk
This is the thumbnailed video. I can't vouch for it.
https://www.youtube.com/watch?v=0Wk_VPEi8Z8
The 232 does appear to have problems with software support…you need Reaper
@mcc I'm reminded of design notes for Forth in the 1980s - the rationale for only supporting 16 bit ints. Because none of the real world sensors and actuators you'd ever interface with had anywhere near a full 16 bits of dynamic range.
After you capture this blazing sound, what DAC is going to play it back? What amplifier is going to play it back without destroying your speakers?
@hyc @mcc Maybe watch the video to see it in action, it does work and has some merit.
I think the way it works is by employing multiple DACs each set at different gain levels to make sure some part of the signal is always captured, and then encoding the end result in a 32-bit float value so it can be boosted or attenuated without maxing it out (hence the "no clipping").
The only practical use of this is to make it possible to salvage a recording after the fact if too much gain was applied.
@cvtsi2sd @hyc @mcc Yeah, it is a bit like that. But instead of making different exposure levels visible at once, like in HDR, this simply helps you to turn down the gain of your audio signal if it turns out it was recorded too hot.
So it's useful, but only in a very specific scenario that can be somewhat easily avoided anyway by simply not turning the gain up too high.
111dB 768kHz / 32-bit 4 ch Advanced Audio ADC The AK5534VN is a 32-bit, 768kHz sampling, differential input A / D converter for digital audio systems.
@mcc there are some fancy ADCs that do adaptive dynamic range, which you could use for floating point representation (essentially translate the adapted dynamic range level to an exponent and the value to a mantissa). they don't directly output IEEE floats; you'd do that in the DSP.
high performance FPADCs are a subject of ongoing engineering efforts in the test equipment world.
I don't know if there is now, but with clever circuit and FPGA design you can in theory do it with a fixed-point ADC + some very rapidly adjusting auto-gain circuits in front of it (giving you the exponent.)
10 years back my employer did some experiments on that for RF signals, but the designers could not get an auto-gain circuit to slew levels fast enough without distorting the fixed-point values while adjusting the incoming power.
But that was at multi-MHz sample rates.
Silly PS: I never know whether it reads better to say "sample rate" or "sampling rate."
A multi-stage analog-to-digital conversion method and system use window functions and translation to match high gain frames of data to target frames of data. The technique selects window data packets for the output stream based the stage of data having the highest gain satisfying selection criteria, such as requiring a frame of data for the respective stage to satisfy a predetermined accuracy of fit value compared to a target frame of data for a zero gain stage.
@mcc 32-bit float for audio uses only the ±1 range. An audio interface that produces float samples will be made such that this range coincides with the limits of the ADC chip. Anything outside of that will be clipped by analogue circuitry.
Floating-point is useful in a processing chain since it lets you normalise the range at the end without worrying about clipping or loss of precision at intermediate stages. In an audio interface, it is quite pointless. Likewise for distribution.
@mcc This gives major Julian Krause vibes.
But also, not knowing what channel it's from, this kind of thumbnail is always such a toss-up. It's either some highly accurate, in-depth technical info, or a massive pile of nonsense.