Dithering in PT

[martthie_08]

I've been recording my mixes within ProTools (currently 11 on HDX) for quite some time now instead of bouncing to disk. This way, I can simultaneously record an unprocessed mixdown, along with a limited version for the client to take out of the studio for approval before the unprocessed mixdown goes out to mastering.

I usually set up my sessions 24 bit, 44.1 KHz interleaved stereo. So far so good, but two things have always been unclear to me:

1. when exporting the limited file (Apple-shift-K) for my clients, I have no options of choosing a desired Dither/Noise shaping algorithm. Does PT do this automagically with preset settings? Normally the export file format will be mp3 / 44.1KHz....

2. is there any advantage in using the provided bit length reduction / noise shaping that most limiter plugins come with even when using this workflow (recording to 24bit, then export with Apple-shift-K)?

thanks for any insights...

[Drew Mazurek]

Originally Posted by martthie_08

Does PT do this automagically with preset settings? Normally the export file format will be mp3 / 44.1KHz....

Yes, there's a chart in the manual spelling out what it's doing. I use this workflow as well and have for years.

[martthie_08]

OK, thanks for pointing me in this direction, the manual states that both Dithering and Noiseshaping using standard Digirack Plugin is automatically used when exporting from 24 to 16 bit, so I guess it makes sense to turn any Dithering and Noiseshaping from my 2-bus limiter off to avoid double processing...

I wonder though if there is a way for me to experiment with different Dithering and Noiseshaping algorithms integrated into my workflow bypassing the standard Digi plugins.

FYI, I've been using FabFilter Pro-L and Waves L3-LL Multi for most of my final limiting and these plugins each provide dedicated Dither/Noiseshaping sections.

[Top Jimmy]

Exporting to a lower bit depth always has dither applied. Bouncing, on the other hand does not. So if you want to get a mix out with your preferred dithering, bounce the final result instead of exporting.

[martthie_08]

So if you want to get a mix out with your preferred dithering, bounce the final result instead of exporting.

understood, but how would I go about doing this?

Record the limited file with 16 Bit dithering and noise shaping of the chosen limiter plugin on a stereo track (as 24 bit) and then do another (offline) bounce as 16 bit without dithering?

the elegancy of working with audio tracks for mixdown is that I only have to have one realtime run-through (with all the analog outboard) and then have all the files I need. This is something I do not wish to loose...

[Rich Breen]

Yes, PT is not particularly elegant WRT this issue. The only way I know of to force a truncate (which is what you want if you're supplying your own dither) is to do a BTD - at least you can do this offline now.

Personally, I use other apps for final prep and delivery that are more tightly focused on that part of the workflow: Wavelab, Triumph, Sample Manager, or even Audacity might be worth looking at.

best,
rich

[Top Jimmy]

Originally Posted by martthie_08

understood, but how would I go about doing this?



Record the limited file with 16 Bit dithering and noise shaping of the chosen limiter plugin on a stereo track (as 24 bit) and then do another (offline) bounce as 16 bit without dithering?



the elegancy of working with audio tracks for mixdown is that I only have to have one realtime run-through (with all the analog outboard) and then have all the files I need. This is something I do not wish to loose...

I would print the mix just as you have been, but leave off the dithering. Then I would put the dithering plugin on the printed track and bounce that track out to 16 bit.

[martthie_08]

I would print the mix just as you have been, but leave off the dithering. Then I would put the dithering plugin on the printed track and bounce that track out to 16 bit.

this seems like a good solution, thanks for that!

although this whole subject is more academic, with the little peak to rms margin I am working with on normal days, I did want to find out what I was missing out on by not exploring the wonderful world of dithering and noise shaping!

now I just have to find out why sometimes HDX randomly crashes my whole system when doing offline bounces, but that is for another thread