Can't burn 24-bit to CD?

All audio CDs are 16 bit.

poflynn wrote:
Exported a Track from a Project to iTunes at 24-bit. iTunes song Info showed it as "Sample Rate 24-bit." Then burned to CD, (Speed: Max, Disc Format: Audio CD, Sound Check off). Then imported from CD back to iTunes (aiff) and it changes to 16-bit! Can a CD not burn at 24-bit? Should I have picked another speed in the Burn Settings window?

Basically, how do I get my tracks on CD at the best possible quality for using later in GB (if original Project is lost, e.g.), or for sending to someone for editing, etc?

Hi Po,

There are really 2 issues that are getting mixed up: audio CDs that play in CD players, and making archival discs at highest resolutions possible.

To clarify, the type of audio CDs playable in CD players are called "red book" and are at 16 bits (not 24 bits). This is what iTunes calls audio CD. If you record a project at 24 bits and want to distribute it on traditional red book audio CDs, you will need to reduce the bit length from 24 bits to 16 bits (what iTunes did automatically when you asked to burn a CD).

When you reduce the length from 24 to 16 bits, there are two ways to do this. First, you can simply chop off the extra bits (which is easy but bad, since you loose meaningful information). The other way is to dither down from 24 to 16 bits - use algorithms that are designed to stuff as much of the 24 bit audio information into the smaller 16 bit file, rather than arbitrarily chopping off the extra bits. Logic and many audio editors offers dither options when going from 24 bits to 16; I'm not sure if GB automatically applies dither or arbitrarily chops (my guess would be that it dithers - maybe someone else knows for sure?). In iTunes, I would guess the opposite, that it simply chops (again, just a guess).

So... when producing a traditional redbook audio CD that will play in a CD player from a 24 bit project, you need to somehow get from 24 bits to 16 bits.

However, you end your question by asking how to best archive your work for using later in GB or for sending to someone else for editing, which is something else. For this, it doesn't matter if your CD conforms to 16 bit redbook standards and is compatible with traditional CD players. It is more important to preserve as much information as possible. So in this case, you'd want to maintain all 24 bits, and NOT convert to 16 bit redbook standards (an "audio CD" in iTunes).

If I were you, to archive your work at best resolution for future editing, I'd keep it out of iTunes (and its automated processes). Better to "share" it to disk at highest resolution possible, and burn/backup on whatever media you prefer - CD, DVD, holographic crystals, computer punch cards, etc.

isteveus wrote:
All audio CDs are 16 bit.

Except those that aren't. 🙂

(e.g. SACD, DVD-A).

You don't have to use iTunes to burn your files to a CD. Can't you just go to the folder where the 24 bit file or files reside and move it onto a CD and then have the finder burn it? This should keep it 24 bit I believe.

Man, I would love to see 1GB worth of punch cards:

Given a card that is .01" thick and holds 80 bytes, you would need a stack of 12.5 million cards which would be 125,000 inches or a little under 2 miles high!

poflynn wrote:
Okay, lots of useful info. Thanks everyone. And yes, Matti, it really is two different questions.

Do I need to Share to disk first or can I just find the folders in Finder as WarriorAnt suggests? Because what I want is to keep each Track in the Project separate.

In that case, it's just a basic backup, and there wouldn't be anything special about the fact that it's a Garageband file. In other words, you just back up your "My Song" GB project file as is, in the finder.

"Sharing it" creates a stereo mix of your project at whatever resolution you choose. It's like a snapshot of your work at any particular point.

So... what you might want to do is both. Share the project to disk (and back that up) so that you have a reference mix of what the song sounds like the last time you worked on it, and is in a format independent of GB, as well as backup your original project file so you can always go back to GB and continue working on the original tracks.

(I'm stockpiling those punchcards. - My dad, who use to work for RCA and Honeywell in the late '50s/early '60s still loves to tell how an entire large-room-sized computer stored only 10,000 bytes - each byte, of course, being one character).

That reminds me of a line from "Apollo 13" in which Tom Hanks' character says something along those lines, extolling the miracles of computer power and miniaturization at the time (comically outdated from the audience's perspective).

No doubt the same will repeat: future storage will make our hard drives seem as quaint and bloated as punch cards now seem from our current perspective.

poflynn wrote:
Okay, so to clarify (sometimes I need things really spelled out), I can share the song to disk (all tracks, mixed, at once, at the best quality) and backup that .aif file, and/or I can just back up the .band file that's in GB? I was thinking I had to export each track separately and then backup all of those. I guess that's overkill?

Unless I'm missing something, that does sound like overkill. Since all the individual tracks would exist in their raw form - whatever it is - in the project file, backing up the project file is a way to back up all the individual tracks in one fell swoop. Then, as a reference that's independent of GB, I'd also back up a "shared" master in a universal format, like AIFF.

But I'm not sure there's a benefit to backing up individual tracks outside of GB. The only benefit I can think of is if there's a need to bring them into another DAW, but the .band file shouldn't be perishable, so you could always open that up in the future (with GB, Logic, or at the finder level) and extract parts if you have to.

Locking tracks mainly makes the files bigger. You'll save a 32-bit audio rendering of every locked track on top of what space they use anyway. I don't see much sense in that. You mention the effects - if you use an effect on a track that the user who opens the file doesn't have, GB will complain anyway. I assume that the locked tracks will play fine, with the effects, but you won't be able to modify them.