Comment by jrajav | Hacker News Reader

Comment by jrajav | Hacker News Reader

Parent Full thread

You're absolutely right insofar as you're speaking about static audio that's already been produced and finished - there is almost no point in storing anything above 24-bit integer as far as dynamic range even for archival purposes.

However, there is a legitimate purpose behind having higher dynamic range for production purposes and sample sources. There are some recording sources that can actually produce 32-bit audio. Plus, you might want to do some processing on the sound that would end up affecting the dynamic range, or otherwise benefit from the increased resolution. One example is nonlinear processing that generates new musical information from the original signal - you can of course just reduce the gain after processing, but you are then sacrificing some of the resolution of the new combined signal, which itself could otherwise be used by further downstream processes. This all happens post-recording, but can still be musically important before getting to the finished product.

This is why DAWs work in 32-bit or 64-bit processing internally, and why many high-quality sample libraries will come in 32-bit, especially smaller one-shots. I often convert samples to .flac for space reasons, and have to either skip 32-bit .wavs or downsample them to 24.

> However, there is a legitimate purpose behind having higher dynamic range for production purposes and sample sources.

This is the justification for 24-bit audio... is there a reason why 24 bits is not enough here?

If you're capturing audio sources directly, you'd use something like a 24-bit ADC, which you can find easily enough. The "raw" output of the ADC is 24 bits.

If you're doing intermediate processing in your DAW, then the DAW is using single-precision floats (or possibly double), which cannot be losslessly converted either to 32 bit or 24 bit integers, so how would you choose the right format to store? It seems to me that you'd either store the original floating-point data, or you'd perform some kind of lossy conversion to a high-quality archival format... but if you do that, isn't 24 bits good enough? You're quantizing either way, and at 24 bits, you can have plenty of headroom and noise floor at the same time. Loads, even.

There are two justifications, one, for recording - 24-bit is the standard in the studio yes (and more than you need for that context indeed), but 32-bit is more and more the standard for field recordings where the hardware is capable of it and it provides genuine utility, where you often have extremely soft and subtle sounds captured that you want to increase in gain to a more useful level.

Also, once inside the digital world, there are many processes you can perform that add new musical information to the original sound that might be higher in gain but that you want to preserve for downstream processing until you're ready to actually "print" and quantize the final product, at which point, yes, 24-bit will be more than enough.

A microphone, preamp, and ADC that have > 144dB of dynamic range are extraordinarily rare outside of lab equipment.

Physically, you are talking about signals measured in the tens of nano-volts (or nano-amps, depending on the mechanism of the microphone).

The latest Zoom field recorders support 32-bit float recording and achieve a wider dynamic range than that (upwards of 210db) by having a circuit with two different ADCs.

Also, it's less about the absolute resolution, and more about the ability to boost the gain, often by a lot, while still having a wide and useful dynamic range after the fact.

Color me skeptical, that's a wider dynamic range than air

32bit FLOAT is 24 bits of audio data, and has the unique advantage of being the typical internal processing format of plugins and audio workstations, due to the desire for headroom while processing to avoid artifacts from overflows of various kinds, among other things. (Upsampling is also common before performing calculations that may alias or mirror.)

The stacked ADC approach does allow for a wider overall dynamic range, but I would be skeptical of the physical transducers capabilities in using it all, but the 32-but float format here appears to be largely about lossless transfer to a DAW such that further processing is lossless, as we are not converting from int to float and back.

This format could then be said to be useful as a master media format.

The article in the OP is about a flac containing a 32-bit int audio stream, however, which appears less useful and not at all related to 32-bit float

DAWs use floating point numbers, which are not applicable to this discussion. They also waste about half the bits most of the time.

Reply on news.ycombinator.com