Rocinante
Well-known member
Interesting article on 16, 24, and 32 bit.
https://www.sounddevices.com/32-bit-float-files-explained/
https://www.sounddevices.com/32-bit-float-files-explained/
john12ax7 said:Rather misleading / inaccurate imo. When recording your converter will put a limit on max and min levels, 24 bit vs 32 bit float storage makes no difference, you can't even achieve true 24 bit performance at this time
32 bit float can make a difference in post processing, but even there the dynamic range claims are overblown. It's a sliding scale, you can store really large and really small numbers. But you can't simultaneously manipulate really large and really small numbers.
john12ax7 said:Rather misleading / inaccurate imo.
EmRR said:What do you find misleading?
You can manipulate really large and really small floating point values at the same time but there is little point since the small stuff gets swamped by the big stuff...john12ax7 said:Rather misleading / inaccurate imo. When recording your converter will put a limit on max and min levels, 24 bit vs 32 bit float storage makes no difference, you can't even achieve true 24 bit performance at this time
32 bit float can make a difference in post processing, but even there the dynamic range claims are overblown. It's a sliding scale, you can store really large and really small numbers. But you can't simultaneously manipulate really large and really small numbers.
john12ax7 said:Thought I explained it? A converters circuitry would determine its dynamic range. You don't magically gain headroom by choosing to represent the converter data as float vs fixed.
EmRR said:Well, there are multiple types of headroom. This is but one. If you can’t anticipate the dynamic range you might encounter, this offers more latitude.
john12ax7 said:Could you explain what you are referring to? What are the multiple types of headroom for the front end capture?
(I think we can all agree more bits are useful for DSP)
It is not trivial to maintain an input (analog) noise floor lower than the A/D convertors noise floor "and" take advantage of the digital dynamic range (upper bits). Premium convertors will dither the LSB trading the grainy quantization noise for more natural sounding noise floor (but still noise). Digitally boosting (multiplying) a signal encoded too low will amplify the digital noise floor. This sounds better than the digital noise floor of old technology convertors but while the gain does not add any noise of its own, there will always be a noise floor.squarewave said:Actually it seems to me that there's one major caveat here.
If the mic pre and converters are one device (like Sound Devices recorders), then yes, once the mic pre noise floor exceeds the converter noise floor, there is no noise performance benefit. In fact, it is potentially a disadvantage because the signal could be clipped or distorted. You can amplify digitally later with no impact on noise performance.
But! If you have any analog gear in between (and that could just be the output stage of a pre in a separate box) the noise floor of that is going to be relatively high which necessitates that you boost the signal enough to get good noise performance from it.
More is always better right? :user 37518 said:Lets assume that you have 24 bit converter with a maximum input (analog level) of +22dBu, thats 9.76VRMS or a peak voltage of 13.798V, That means that the lowest step (the LSB) the converter can code is 13.798/(2^24) = 0.82 microvolts, thats -122.5dBU (after converting to RMS) of minimimum signal, thats the noise of a 1Kohm resistor across a 20KHz bandwidth, giving a roughly 144.5 dB of dynamic range, most microphones or line level devices are no way near that noise floor, which basically means that the first 3 or 4 bits in your 24 bit converter are always on, effectively making your 24bit converter into a 20 bit or so converter. So whats the point of having a 32bit converter? I do agree that 32 bit float in post processing provides an advantage, but in the conversion stage? I dont think so, to me 20bit is more than enough.
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