Subject:is the (24-)bit depth between effects in SF preserved?

Posted by: polot

Date:7/16/2002 4:41:05 PM

Hi there,

If I apply some effect/process to a file, say a .wav with standard 16-bit depth,
the SF plugins process the data with 24-bit precision (I think, at least that is
what the plugin control window says).

Now I want to apply a second process on the results of the first one.
Question: is the 24-bit depth of the intermediate results preserved between
the plugins/ processes so that quantization error is not unnecessarily introduced?
In other words, is the second plugin receiving 24-bit samples (per channel)
or not.

I would expect this to be so, at least as long as I don't "Save" the results of
the first process.

For an example, for improving old 78 vinyl recording, I found that doing first
Click and Crackle Removal, and then Noise Reduction, produces good results.

I don't want to introduce distortion between the two processes, which would be
necessarily introduced if the intermediate results of the Click and Crackle Removal
are truncated/dithered/noise-shaped before executing the Noise Reduction process.

If SF does not preserve bit-depth/precision automatically as expected (by me at
least, as long as I don't save the intermediate results as a 16-bit .wav), what is
the way to "force" SF to do so?: save the results into an intermediate file in a
24-bit format?, will this preserve the 24-bits or will it first create a temp 16-bit
".wav" kind of format and then expand this to 24-bits, defeating what I want to do?.
Which format would be the best to save the intermediate 24-bit-deep results then?

I looked for any comments/threads about this in the web and in this forum but
found nothing interesting. Also the SF manual does not describe what happens
to the bit-depth of intermediate results when applying multiple processes and
the Sound Forge Power book does not get even close to discussing any of this.

Any input or pointers to the information will be highly appreciated. The first that
provides a good, authoritative, complete answer may get a free lunch at Chez
Panisse in Berkeley, CA.

Thanks in advance!!

-Polo

Subject:RE: is the (24-)bit depth between effects in SF preserved?

Reply by: Chienworks

Date:7/16/2002 4:46:32 PM

I'm not sure about the 24 you're seeing, but Sonic Foundry maintains repeatedly that they process everything at 32 bits. I would assume this means all 32 bits are preserved through all effects chains.

Subject:RE: is the (24-)bit depth between effects in SF preserved?

Reply by: polot

Date:7/16/2002 5:09:23 PM

The 24-bit that I am seeing can be seen by anyone by opening any plugin,
e.g. "Distortion" by clicking DX Favorites | Sonic Foundry | Distortion,
and looking at the bottom right of the Distortion parameters window that
appears. It says "(24-bit Processing)". It does not say 32-bits.

I don't want to assume anything, but rather I am seeking to authoritatively
either confirm or negate that in the process that I described in my initial posting,
the 24-bit processing precision that the plugins advertise is preserved when
I apply multiple effects without saving the intermediate results between them.

Building a "chain", as it is possible to do in SF 6.0 could be a solution
if that *is* the solution, of which I have no evidence right now.
I was talking about manually execute one process after the other,
without saving the intermediate 24-bit results (if at all available) and
expecting the unaltered, undithered, untruncated not-noise-shaped,
results being fed to the second plugin.

Thanks for trying.
Any other takers?
Thanks again in advance.
-Polo

Subject:RE: is the (24-)bit depth between effects in SF preserved?

Reply by: RikTheRik

Date:7/16/2002 6:55:19 PM

All the plugin do process at 32 bit besides what is written under the plugin. I doubt very much that there is an intermediate 24 bit result !! I think there is a chain of streaming in 32 bits between all plugins.

Subject:RE: is the (24-)bit depth between effects in SF preserved?

Reply by: Sonic

Date:7/16/2002 7:09:05 PM

The output of any effect, process, or chain, regardless of the processing depth, is converted back to the source file's bit-depth with no dither and no noise shaping.

If you wish to retain higher precision, go to Options->Preferences->File and check "Use IEEE Float temporary files". When enabled, all temporary files will be generated as 32- or 64-bit IEEE Float (32-bit float for <=24-bit PCM, otherwise 64-bit double). The results of any process will be stored in this format until the file is saved.

Processing precision is maintained between effects in a chain (SF6.0).

Subject:RE: is the (24-)bit depth between effects in SF preserved?

Reply by: polot

Date:7/16/2002 8:05:34 PM

Thanks a lot, Jason.
Is this info available also in the SF documentation/help files?
Thanks once more!
-Polo

Subject:RE: is the (24-)bit depth between effects in SF preserved?

Reply by: Sonic

Date:7/18/2002 10:49:11 AM

It should show up in the preferences section and the "What's This?" help on the pref page itself.