sample rate, bit depth in rendering final mix

[3buddhas]

Forum friends,
Same question asked three ways.
When rendering a mix for mastering, CD album the goal, is there advantage to upping sample rate and bit depth from my 44.1/24-bit settings?
Might the upsampling/resampling at higher rezzies make for better mastering and CD sound, even though the res would be knocked back down again for CD burning?
When rendering at a higher sample rate and bit depth than project settings, would you guess/know there'd be not only bigger files but higher sound quality as well?
Cheers

[3buddhas]

Correction. My project setting is 64-bit float.

[serr]

You have a 24 bit recording, mix, and master. Might as well save that even if you don't wish to produce or release a more high falootin format than CD. Reduce to 44.1k and 16 bit from the 24 bit original sample rate master.

CD is a one trick format. 16 bit at 44.1k. You can't put higher def audio in the CD format. Release in flac files or bluray disc for that.

The sound of your 24 bit final master is your target. You might try different dither noise options for the reduction to 16 bit and see if one sounds more transparent.

The work you did upstream - from recording technique and quality to mix work - is where your 'quality' comes from. The 24 bit final master at the original recording and mix sample rate preserves it fully.

A reduction to CD shouldn't be glaring but you might hear a difference after reducing to 16 bit.

The harsh brickwall limiting and treble boosting you hear with many CD versions of albums are intentional mastering decisions (or lack thereof). Reducing to 16/44.1 doesn't just do that by itself.


FYI
The internal mix engine paths are 64 bit floating point. Which preserves the 24 bit resolution of your recorded tracks no matter how low you put a fader.

[3buddhas]

Many thanks for the in-(bit)-depth reply, serr. Much for me to chew on, and it's answering my questions.

Seems you're saying quality is not added by up-/re-sampling. Quality is upstream of such settings. Just as with increasing resolution in Photoshop. Quality/resolution of a digital image comes from scanning resolution. If it's not there at the scan (recording), it won't get added by upping resolution later.

I'm guessing you mean "reduction to CD should NOT be glaring, but ... " But for the limiting and presence-boosting typical of CD mastering?

Thanks for the FYI. I've heard folks on both sides—-Lowering fader doesn't lower resolution vs. lowering fader does lower resolution. Maybe it's a desk vs. DAW thing. I'm leaning to your view--in 64-bit DAW float lower fader doesn't mean lower rez.

Cheers

Originally Posted by serr

A reduction to CD should be glaring but you might hear a difference after reducing to 16 bit.

The harsh brickwall limiting and treble boosting you hear with many CD versions of albums are intentional mastering decisions (or lack thereof). Reducing to 16/44.1 doesn't just do that by itself.


FYI
The internal mix engine paths are 64 bit floating point. Which preserves the 24 bit resolution of your recorded tracks no matter how low you put a fader.

[serr]

Yes "shouldn't be glaring"

Upsampling SD program to HD would make it sound more transparently like the HD original on DA converters that run cleaner at HD vs SD. There is no quality added. It's simply making the converter machine not have to anti-alias filter the sampling rate frequency. It's preventing degradation.

That might sound ass backwards...
How could a further conversion - upsampling - prevent degradation?!
The degradation in this example would come about from the AD converter's performance in SD mode. Not from the reduced to SD data. Because even though the data has been reduced to SD, that doesn't touch the actual audio band.

Again, this assumes no one is entertaining the idea that any artifacts above the range of hearing are useful or perceivable. Many people seem to entertain this notion. Some use it as a strawman to state "You can't hear those frequencies so HD is bs!". Trying to suggest that the purpose of HD sampling was to capture above the range of hearing.

Fixed point digital does in fact lose resolution as the volume goes down. Literally losing fidelity as you lower the volume. Put a half volume signal into a 16 bit container and you use 8 bits. That's an 8 bit recording. You need to pay attention to levels with 16 bit. That's still a decent amount of resolution for a finished master. Pop stuff that's squashed dynamically doesn't even hit the edges! Classical or artsy music might get hit a little. This WAS a factor in starting the volume wars. 24 bit gives you an 8 bit "noise floor" bed with 16 bits above that. True 96db dynamic range with pretty full resolution on the very bottom.

Floating point formats preserve a much wider range when the decimal can float and preserve the 'meat' of the numbers instead of padding zeros. Math.

Consumer format is 24 bit fixed... so get your levels in order at the end of your mixing chain!

[3buddhas]

Many thanks, serr, for a second thoughtful reply. Lemme see if I understand.

Originally Posted by serr

Upsampling SD program to HD would make it sound more transparently like the HD original on DA converters that run cleaner at HD vs SD. There is no quality added. It's simply making the converter machine not have to anti-alias filter the sampling rate frequency. It's preventing degradation.

So upsampling SD (is that 44.1???) to HD (48? 96?) frees the mastering lab's converter from having to anti-alias, giving the lab a more faithful version of the original. No quality or resolution is added by the upsampling, but less quality is lost in the DA conversion. This then would be a good argument FOR upsampling a mixdown headed for mastering, yes?

Originally Posted by serr

Consumer format is 24 bit fixed... so get your levels in order at the end of your mixing chain!

Not sure I get this point yet, but would like to. I've heard "Don't worry about mid-chain overs because with floating point math they can be fixed end-chain" (Andrew Scheps, Kenny Gioia). David Gnozzi argues mid-chain overs miss out on plugin sweet spots. I wonder if I'm even close to getting YOUR point.
Cheers

[ashcat_lt]

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