[UnderTow]

Originally Posted by Cellotron

Allistair -
I've never seen Bob Lentini deliberately vague about this. In response to inquiries on his forum he's spelled out explicitly what it does in some posts, and in direct phone conversation with him he's also confirmed and clarified some points for me.

to wit:
* Multiples and divides are in fact done using 64bit double precision fixed point math.
This returns a full 32bit DWORD (truncated, not dithered, from the 64bit) before being handed off to the next signal process.

This is why I say he is being vague. If a multiply or divide operation returns a 32 bit word it is effectively a 32 bit operation. It is even truncated which means you lose any additional precision that might occur. (Not that there really is any). Anything in between is irrelevant. That is the resolution available and nothing more. This is exactly what I was alluding to before. To me this is similar to saying a 32 bit float calculation has 80 bit resolution when using the CPU float units. It is stretching the truth too far for my taste.

* The built in eq's use 64bit floating point math however. Originally fixed point math was used for these as well but then he found it was causing some DC offset in some operations with this method so he changed the algorithm for these.
* When a VST plugin is placed in line the 32bit integer figure has to be converted to 32bit float first, and then the plugin handles the math at whatever maximum allowable bit depth it has been coded at. The returned figure needs to be converted back again from floating point to integer.
* SAW native plugins from RML Labs all use fixed point math except for the Reverberator which uses 32bit floating point as it is legacy code created by another developer
* SAW native plugins from JMS Audioware afaik 64bit floating point math.
* SAW native plugins from Sonoris use 64bit double precision fixed point math (except for some filters which use 64bit floating point) and return a full 32bit DWORD with TPDF dither used when requantizing this from the 64bit figure.
* Unless the native dither is activated or a dither plugin is placed just prior to output then the 32bit fixed point figure will be truncated to 24bit prior to hand off to the DAC.

Thanks for clarifying all the details.

So I actually think Bob Lentini has been more forth coming about what's actually going "under the hood" with his DAW app than nearly any other developer with the exception of Digidesign, who went to the length of issuing a white paper.

Or Cakewalk. The devs have repeatedly discussed the details of the audio engine on the forum. Sonar has full 64 bit float throughout. There are a few legacy plugins but any of the new ones are 64 bit float. Any 3rd party VST 2.4 plugins will also communicate at 64 bit float. The limitation is the audio I/O and/or file bit depth if the user chooses less than 64 bit. (Which you usually will of course but if you want to use 64 bit, you can).

Anyway - SAWStudio is definitely not for everyone as it commands are a little different than other DAW's, and it's price is in the higher range for DAW apps - but I've been using some version of it since 1994 so that I'm super quick on it, it's incredibly stable, the support is excellent, and do find that the results after processing is done with it remain very high quality.

If it works for you and sounds good, what else can you ask for?

Personally I don't really think 64 bit makes that much difference in the end for most operations. For the more complex stuff any plugin can use a larger bit depth where needed. But yes I turn on the "double-precision" switch in Sonar if I sue it. If it is there...

Alistair