I work in the 24 bit mode for my projects, but I keep the setting for rendering audio at the default 32 bit resolution because it is supposed to achieve better results for rendering. So when I ‘bounce to clips’ it raises some questions as to what happens in the 24 bit project.
 
Do I now have a hybrid file with some 32 bit clips (the rendered clips) and some 24 bit clips (the un-rendered clips) in the one project? Or are the rendered clips still 24 bit clips even though the rendering process is done in 32 bit mode?
 
If the rendered clips are now 32 bit clips, how do I go about exporting the audio when the project is finished? In other words, if the file contains some 32 bit clips and some 24 bit clips, wouldn’t I have to apply dither if I want the resulting audio to be 24 bit?
 
It would be a shame to have to add dither in this scenario, affecting the whole file when only some of the clips really require dithering down. Wouldn’t I be better off rendering clips (i.e. for the ‘bounce to clips’ function) in 24 bit resolution and save the added step of applying dither during export?

Can't you just always render / export projects to 32 bit . . . then, afterwards dither down to 16 bit for CD, or 24 bit for online streaming, depending on where you are planning on having them played ?

There's theory and then there's practice. And in practice...
 
1. Dither isn't necessary when converting 32-bit files to 24 bits, so don't worry about dither.
 
2. Despite what you may have heard, the truth is there is almost never any audible difference between 32- and 24-bit files. 
 
3. If your audio originated from an ADC then you never had either one to begin with, as audio interfaces are really only capable of between 20- and 22-bit resolution. The least-significant bits start out as random noise, and remain random noise whether you store them as 24, 32 or 64 bits.
 
4. Even if your audio is entirely generated in the box, e.g. 24-bit samples, it makes no quality difference if you render them at 32. All you're doing is tacking on some zeroes.
 
Simplest approach is to stay at 32 bits throughout. There is no downside. 
 
 

Thank you Noynekker and Bitflipper.
 
There is obviously a lot I don't understand about bit rate. Bitflipper, you said that it makes no difference if I render at 32 bit, that I am just adding zeros. So why don't I just render in 24 bit and keep my files smaller? (I assume 32 bit files are larger than 24?)

bitflipper
There's theory and then there's practice. And in practice...
 
1. Dither isn't necessary when converting 32-bit files to 24 bits, so don't worry about dither.
 
2. Despite what you may have heard, the truth is there is almost never any audible difference between 32- and 24-bit files. 
 
3. If your audio originated from an ADC then you never had either one to begin with, as audio interfaces are really only capable of between 20- and 22-bit resolution. The least-significant bits start out as random noise, and remain random noise whether you store them as 24, 32 or 64 bits.
 
4. Even if your audio is entirely generated in the box, e.g. 24-bit samples, it makes no quality difference if you render them at 32. All you're doing is tacking on some zeroes.
 
Simplest approach is to stay at 32 bits throughout. There is no downside. 
 
 

Actually Bit you can hear audiable artifacts if you don't use 32bitfp audio files, and as some will know I use 64bitfp audio files. Where bit is right, is say you record an acoustic track with minimal processing. You will not hear much difference between 24bit 32bit and 64bit. And indeed if this is your goal in regards to recording or if you're planning to send your audio in and out of the box or you do your processing via outboard gear - then stick with plain old 24bit - unless you're planning to get Ifools to distribute, because they use a 32bit conversion process.

Where bit is wrong is if you process your files heavily like I do. This includes Melodyne. The difference between a 24bit Melodyne file and 64bit is night and day. The 24bit file tends to sound a bit grainy. It's also night and day in regards to analogue emulation effects. Now bit and others might say 96khz fixes some of these problems...and they may, I have not done the tests to really know, and indeed it's been decided that a beginning point to hi resolution audio is a 24bit 96khz master file. But I believe, although I don't have a test file at this point to demonstrate indefatigably, that 64bitfp 48khz master files are the starting point in regards to hi resolution audio files. For the above reasons.

There will be lots of hate poured onto me for saying what I've just said. But the proofs in the pudding, go to my website in signature to hear what I believe is hi resolution audio up until the distribution point or Youfool.

Thanks BenMMus
 
So, as my audio interface (RME Fireface 800) is only officially 24 bit it makes no sense to record anything going through it at 32 bit, because it will still be a 24 bit recording. But for processing effects, 32 bit or higher will achieve a better result?
 
Here’s the grey area for me: it seems that the place for changing the default bit rate of your projects is in the ‘Record Bit Depth’ box (Preferences > Audio Data > Record Bit Depth). But doesn’t this setting only affect the recording of an audio clip – and doesn’t apply to MIDI recording, or to the bit depth of anything you render, or to the final mixdown/export process?
 
Question: does the ‘Render Bit Depth’ setting (Preferences > Audio Data > Render Bit Depth) also affect the final ‘Export Audio’ process? (In other words, does the Export Audio process come under the heading of Rendering, affected by the Render Bit Depth setting?) Or is it only the settings in the Export Audio window that apply in this process? For example, if I have a project with a bunch of plugins that have not been rendered yet on audio tracks, and a bunch of virtual instrument MIDI tracks that have not been bounced to audio yet, and I have my Render Bit Depth at 64 bit and I export the project, am I effectively getting a 64 bit rendered file as a result? Or do the settings in the Export Audio window take over at this point?

Export settings take over.

I render to 32 bit.

I don't agree that the least significant bit doesn't matter. When i make a file with only the least significant bit from a 24 bit wave and normalize, i can identify the song.

Regardless of your dither settings, unless necessary they will not be applied. This from Noel, cto.

gswitz
I don't agree that the least significant bit doesn't matter. When i make a file with only the least significant bit from a 24 bit wave and normalize, i can identify the song.

There are good reasons for using 32-bit data, having to do with sinking rounding errors down into the noise floor and not letting them accumulate to the point of audibility. But I'm not talking about signal processing, but rather rendering, in response to the original question. Once exported as a final product, human ears are incapable of differentiating between 24- and 32-bit data.
 
Not that I doubt your hearing acuity, Geoff. You're younger than me, so there's no question you hear better than I do. However, I think I can make the case that no human can hear the difference between rendered files at 24 vs. 32 bits.
 
Look at it this way...whatever differences exist between a 24-bit file and its 32-bit equivalent lie below -144 decibels. The full range of human hearing is only ~120 dB. Now, if you were a barn owl, you actually could hear something 14 dB below the threshold of (human) hearing, e.g. a mouse walking half a mile away. But you couldn't record that even with the best microphone on the planet, and even if you could you wouldn't be able to hear it.
 
The lowest known sound level ever achieved is -14 dBSPL (in an anechoic chamber at Microsoft). You'd have to install a jet engine in that chamber to realize a 144 dB range. If you were then able to pick out a mosquito buzzing 10 ft away - while the engine was running - then I'd believe you can hear what's happening at -144 dB and below.

Thanks Gswitz for chiming in and clarifying that the export settings take over.
 
So just to clarify: even though the export setting takes over from the 'render bit depth' setting, exporting a project is still regarded as a form of rendering?
 

Yes. "Render" just means to save a fully-processed track or mix, whether by bouncing, freezing or exporting.