ProTools question

[shaneperc]

Hi,
Does anyone know the internal resolution of ProTools? I'm just wondering, and since this is ProTools country, someone around here probably knows.

Thanks!
Shane

[PDupre]

Don't understand the question. Please elaborate.

[shaneperc]

I'm talking about the internal wordlength that ProTools uses to perform gain change functions. Most of the eq, compression, and other special case gain changes are handled by the plugins, which have their own resolution. I'm interested in what wordlength the faders operate. If they're adjusting the gain at 24 bits, and you're recording at 24 bits, then the LSBs are more subject to quantization errors. This is the reason why companies like Waves use 48bit internal resolution for their processing functions.
Some companies are starting to get into higher DSP resolution, like Steinberg with VST/32. I personally think Cubase audio sounds substandard, but if you've ever listened to the difference between recording in 24bit mode and 32bit mode, the difference is notable. (They might also be doing something else different with their TrueTape 32 bit, but I don't know.) A better example would be Sonic Solutions, which has a 48 bit internal resolution.
Anyways, I just wanted to see if someone knows the internal wordlength of ProTools.

[shaneperc]

I agree with you, Justin. Then again, I don't think there's anyone who, in their right mind, would argue that specs are more important than sound quality. (Well, I'm sure there are SOME people:)).
Just in case anyone's wondering though, this thread was started out of pure curiosity, and not calling into question the quality of ProTools. PT might very well perform DSP at a 24bit resolution, but will that change the way it sounds right now? No, of course not. It will still sound great, but I was just wondering for my own edification.
PS I'm also a big fan of DAE. Quite a set of algorhythms they have going there!

[Nika]

The bussing of all channels in Protools is 24 bit. Each fader is capable of more than 24 bit which we know because there is a potential +6dB of gain on each fader, indicating that each fader is actually 25 bit at least, and more likely 32bit, though I'm not sure about that.

The data bussing from each fader to aux busses and all of the plug-ins is 24 bit, though. Much of this is a limitation of the Motorola 56xxx series processor and how much throughput it has. Those processors are limited to 24 bit inputs for practical applications (thus are most external effects processors as many of them use those very chips!)

The summing bus in Protools I believe is 32 bits. Individual plugins can operate at much higher bit rates, though.


Does this answer the question?

Thanx!
Nika.

[shaneperc]

Yes! Thank you, Nika. That is a strange thing with the faders going to an additional 6db. Obviously, that's exactly one bit more, but a 25bit word would be really awkward to write code around. Then again, maybe not. Maybe it uses an internal 32bit word, but only one of the additional 8 bits is accessible to the user, using the other 7 for some mathematical headroom. Right now, I'm going to stop writing for fear of becoming even nerdier.

[David Klausner]

I'm not sure if this is what the question was originally asking, but the internal mixer in a ProTools TDM system is done with 52 bit floating point math. The PT LE mixer is done with 32 bit floating point.

[Nika]

David,

I believe that the accumulator itself is actually smaller than that. I thought that the accumulator was 32 bit fixed point. I could be wrong here.

Nika.

[shaneperc]

Nika and David, I'm just curious, but do you guys ever see eachother at work? It makes me laugh to think about you guys writing eachother posts while at your desks, which are separated by 30 feet of cubicle partitions. :)
(Sorry, but that's the picture I have in my head everytime I read posts between you two.)

[Nika]

Shane,

Until a few weeks ago we sat right next to each other. Now we sit about 10' from each other. There's one cubicle wall that divides us.

Nika.

[shaneperc]

Hilarious! I keep thinking about the scene in Office Space where the guy with the big glasses and inferiority complex (don't remember his name) calls Peter in the next cubicle to rant about his job. Except, instead of ranting about jobs, carrying on about the merits of tube preamps.

[Nika]

Shane,

Well, you see, we're both rather consumed in our work, and only interface a few times a day. If I'm on the phone on hold and see a question on the forum I can answer I do so - without getting Dave's permission or input. I'm sure he does the same. And there are about 15 other people in this building that also frequent this forum and that's just kind of the way it works.

Office space was a hilarious movie for those of us in cubicled office environments. It's not uncommon at all for me to call someone a few cubicles away on the telephone to ask a question. Most often I just email them, though. As odd as it sounds, it's just part of a certain style of efficiency that Sweetwater has.

Now what I personally think is REALLY funny is on another forum that I frequent, one of the members lives maybe eight houses from mine, and he and I CONSTANTLY answer each other's questions on line, without ever thinking of picking up the phone or just walking over there.

Anyway, I'm glad we could be a source of amusement for you.

:)

Nika.