32Bit Dial vs 24 Bit Dial

[kd_special]

Using PT 10HD

Is there reason to up convert 24Bit dial to 32 Bit if you know you are going to use heavy Audio suite Processing i.e. Noise reduction? I believe audio suite plugs are 32 Bit in PT 10 so no dithering correct?.

If so does the whole process become obsolete because you will eventually at some point have to convert it back down to 24Bit?

for example in the mix back to 24Bit or as a stem to bring into a 24Bit mix session.

Is dithering something PT does well or should you use a separate plug to convert it back down to 24Bit

thanks in advance

[CME]

There's no reason to record 32-bit float audio, as there are very few, if any, interfaces/converters that output 32-bits. So you're not gaining anything at that stage.

However I mostly mix audio that is recorded elsewhere. And I set my sessions up as 32-bit. You don't have to convert the audio files. Pro tools will play back 24-bit files in a 32-bit session no problem.

My reasoning is, while I've not read or heard anyone confirm this, that it might allow the audio to stay 32-bit as it passes between plugs.

And to explain that a bit more. Yes I use 24-bit audio. But once an audio file goes through a plug-in and is processed it is probably a 32-bit or maybe even 64-bit file inside the plug. So it must be converted back down before going to the next plug or mix engine.

And I do know in earlier versions of pro tools it had to be converted back to 24-bits before leaving the plug. So it had to be truncated/dithered down. But if pt now allows plugs to pass 32-bit float files there's no/less need for truncation or dither. It can simply output the result of the plug-in process. Depending on how the plugs process the audio.

And if I'm right it also gives more headroom through the mixing process. But that's just my opinion. Take it for what it's worth.

[kd_special]

Originally Posted by CME

However I mostly mix audio that is recorded elsewhere. And I set my sessions up as 32-bit. You don't have to convert the audio files. Pro tools will play back 24-bit files in a 32-bit session no problem.

what is the bit rate of the audio you usually get from elsewhere?

Originally Posted by CME

My reasoning is, while I've not read or heard anyone confirm this, that it might allow the audio to stay 32-bit as it passes between plugs.

I have also herd this from a colleague. Less dithering = more headroom is what he was getting at.

[CME]

Originally Posted by kd_special

what is the bit rate of the audio you usually get from elsewhere?







I have also herd this from a colleague. Less dithering = more headroom is what he was getting at.

It's 48khz. I record it also. It's the audio from our church services. We use an iLive and record via Dante into reaper. I then import the audio files into pro tools.

And no dither isn't related to headroom directly. Dither is the process of adding noise to the audio when rounding the math back to fixed point after being floating point. The noise is super high in frequency, but I guess it does indirectly steal some headroom. But not enough headroom to matter. The noise on the other hand is something to consider.

The difference in headroom is due to floating point vs fixed point. A 24-bit fixed point file has a maximum dynamic range of 144dB. A 32-bit file has a theoretical dynamic range of something crazy like 1600dB. But 144dB is much more than needed. But add the extra dynamic range and the potential to cut out some dithering and IMO it makes sense to use 32-bit float sessions.

[kd_special]

Thanks for the reply

Originally Posted by CME

It's 48khz.

Sorry what bit rate?

Originally Posted by CME

The difference in headroom is due to floating point vs fixed point. A 24-bit fixed point file has a maximum dynamic range of 144dB. A 32-bit file has a theoretical dynamic range of something crazy like 1600dB. But 144dB is much more than needed. But add the extra dynamic range and the potential to cut out some dithering and IMO it makes sense to use 32-bit float sessions.

But if you have 24bit audio the run it through a plug its dithers it to 32Bit to go into the plug and on the way out to go back to 24bit?

Or after you audio suite (noise reduce) a clip it converts to 32bit in the timeline?

I think since my colleague knows he will be doing multiple passes at noise reduction he's trying to save some dithering. thus reducing noise


thanks in advance

[kd_special]

Anyone else got any ideas?

thanks kindly in advance

[CME]

Dithering is only necessary for reducing bit depth.

And it works something like this. Pro tools reads the audio file. It sends it to the plug ins. The plug ins process the audio. Most plugs use either 32-bit or 64-bit floating point math. So once it's been processed by the plug-in the audio stream is no longer 24-bit unless it's converted back. In older versions of pro tools the plug in had to do this. So the plug had to either truncate or dither back to 24-bit fixed before sending the audio stream to the next part of the mix engine.

But one thing to note is the actual audio file is still at the beginning of the chain untouched. Think of it like a tape machine. Unless you rerecord the audio feeding the mixer, it's still the original take. You just hear the result of the mixer-plug ins on the audio file/tape.

And just to point out I'm only assuming pro tools will now allow the plugs to keep the audio as 32-bit float if you select that option. So there is no need for truncation/dither between plugs. I've never read that officially.

Maybe I explained it a little better that time.

[kd_special]

Thanks for the reply

and that makes perfect sense to me. The engineer has now changed his session to 32 bit float but keep all the audio from the 24Bit AAF at 24 Bit.

instead of converting it all.

So one last question.

When you have 24 BIt audio in your 32BIt float timeline then you audio suite RX noise that Clip. what bit rate does it go back in the timeline. 24Bit becasue thats what the file was originally? Or 32 because thats what you timeline states?

i may have to test this to find out.
thanks
kd

[CME]

Originally Posted by kd_special

Thanks for the reply



and that makes perfect sense to me. The engineer has now changed his session to 32 bit float but keep all the audio from the 24Bit AAF at 24 Bit.



instead of converting it all.



So one last question.



When you have 24 BIt audio in your 32BIt float timeline then you audio suite RX noise that Clip. what bit rate does it go back in the timeline. 24Bit becasue thats what the file was originally? Or 32 because thats what you timeline states?



i may have to test this to find out.

thanks

kd

I believe it will become 32-bit float. But probably worth a test to confirm.

[Greg Malcangi]

Originally Posted by kd_special

Is there reason to up convert 24Bit dial to 32 Bit if you know you are going to use heavy Audio suite Processing i.e. Noise reduction?

No, none whatsoever!