Mastering in Vegas - SRC, Dithering & Bit Conversion advice requested

SoundBloke wrote on 5/20/2003, 8:50 PM

What would the recommended order of processing be for rendering a project originally multi-tracked in 24/96 to a stereo 16/44.1 wave file on the PC platform - primarily using Vegas 4 but hopefully taking advantage of the Waves L2 plugin's noise-shaping algorithm, with Soundforge available as an additional tool if needed?

My limited understanding is that generally Sample Rate Conversion, followed by Dithering & Noise-Shaping, and finally Bit Conversion, should be the very last
processes occuring in the mastering chain - right?

I'm rather fuzzy though about how Vegas internally implements the "Render As" process, i.e. in what order are the operations carried out when a plugin such as L2 is attached to the Master Bus...

When the 24/96 project is "rendered as 16/44.1", does Vegas truncate, round or perhaps even automatically add dither? At what point does the down-sampling
occur, and how good is the SRC algorithm used by Vegas?

If I stubbornly want to use L2's Dither and Noise-Shaping, and if it's recommended that SRC takes place BEFORE the Dithering, does Vegas allow one to down-sample from 96 KHz to 44.1KHz first, before dithering/bit-conversion through the L2 plugin on the Master Bus?

I am assuming that Vegas's internal arithmetic occurs at the 32-bit floating point level...

Hopefully these clumsily-phrased questions will actually make sense to some of the gurus out here, would appreciate any and all suggestions/pointers...thanks! :)

E

P.S. If Waves L2's IDR isn't recommended, I also have Logic Platinum's built-in POW-r dithering algorithm available as an alternative.

Comments

Rahman wrote on 5/22/2003, 8:56 AM

Hi Soundblocke:

I hope one of the guru's respond because i have exactly the same Q's :

1) on mixdown / render does Vegas 1st convert file from 96/48 to 44.1k?

2) if you do use the L1 or L2 at the end of the master chain and have some
plugins (like timeworks, Ozone, etc.) preceding them with 64-bit resolution,
will the resulting 44.1k/16-bit preset take all this into account and dither info
from L2 down to 16-bits?

3) I also noted that Sound Forge doesn't have a "render as" option in the menu.
(However, what it does have is a "process selection" option in the plugin window).
does the "process selection" with the L1/L2 at the end of the chain, dither down
to 16-bits? If you now "save as" a 16 bit file, are the other 8 bits of data zero's ???

As you can see, I'm as confused as you on this one. Hopefully, someone can give us
a little guidance here.

thanks

SckidMarq wrote on 5/22/2003, 11:13 AM

I'm also waiting for some professional input on this.

fishtank wrote on 5/22/2003, 3:04 PM

I'm pretty sure the Vegas manual does not do a very good job descriping how the "Render As" works. I always end up using Sound Forge 6.0 to *Master* my stuff with the L2 last in the chain (performing sample rate conversion first if not at 44.1 already). I then do the bit depth conversion as the final step before burning a CD. The nice thing is that by rendering the Vegas project to a 24 bit stereo file I have more to work with if I want to *tweak* it later in Sound Forge.

FWIW - I have heard many good things about the Waves IDR. I seriously doubt any of the competing dithering schemes will make much of a difference in the positive direction.

IMHO -I have yet to be convinced that 96 KHz (or above) sampling provides much advantage other than greatly increasing the amount of processing needed. Today's oversampling converters pretty much negate the need for very high sampling rates. I realize that many insist on using high sample rates, but unfortunately most people seem to think that MP3's sound as good as CD's. The fact is, I couldn't even come close to mixing any amount if 96KHz tracks with the amount of Direct X plugs I end up using. Thus I work at 24/44.1 or 24/48 as my experimentation with higher sample rates has not proven to me it is worth the added CPU load.

pwppch wrote on 5/22/2003, 7:04 PM

1) on mixdown / render does Vegas 1st convert file from 96/48 to 44.1k?

2) if you do use the L1 or L2 at the end of the master chain and have some
plugins (like timeworks, Ozone, etc.) preceding them with 64-bit resolution,
will the resulting 44.1k/16-bit preset take all this into account and dither info
from L2 down to 16-bits?

Rahman wrote on 5/23/2003, 9:49 AM

Hello Vegas Fam:

thanks Peter, but I am still a bit unclear about the following:

"For the typical case of a single master with multiple buses/tracks feeding the master, the master is the final rendering stop before conversion from floating point to the rendered file format. That is, the output from the master bus 32 bit floating point at the rendering templates sample rate".

so does this mean that if an L1 or L2 is on the end of the effects chain before
hitting the template, the 32-bit file will have already been dithered to 16 bits with the
other 16 bits of data insignificant for the resulting 16-bit/44k wave file?

Also:

" We don't do any noise shaping or dithering to the floating point stream from the master bus. Yes, this is something that others have asked for. The ability to connect dithering/noise shaping/mastering plugins POST master bus fader. It is something we are looking at for the next version of Vegas".

This seems a little strange because in Vegas 3, the master bus fader was PRE- master effects. This was appearantly changed for Version 4, which had me very confused.
So I submitted a post on the forum about the master effects bus and fader issue, and the response I got was:

"The master effects in Vegas 4 are now PRE- master fader, (as they should have been all along)! "

I have run some tests and verified that indeed the master effects are POST fader in V3 and definitely PRE fader in V4.

Therefore, are you saying that if I want to dither / noise shape from 32-bit down to
16-bits, I have to go back to V3 (Where I can add noise shaping plugs after the master bus fader) ? If so, does V3 hit the 16-bit render template file format at the the output of the master effects & POST fader ?

Sorry to dwell on the issue. I am clear"er" but still a bit confused.

thanks

rahman