Importing 24bit/96kHz audio in a 16bit/44.1kHz session.

[michele.bartolettistella]

Dear Forum,

sometimes I use Pro Tools to convert my Hi-Res (24bit/96kHz, tipically) audio files bought through the Internet, when I want to write them on audio CD.

Normally I don't need to edit the tracks, so I simply create a CD-quality (16bit/44.1kHz - Interleaved) session, then I import the tracks: when Pro Tools finishes converting and adding them to the clip list, in fact I do have my CD-quality tracks in the Audio Files folder, ready to be burned to a CD.

Now my question. No problem for the sampling rate: I see that Pro Tools re-samples the files; but what about the bit-depth? Should I take some prudence, expecting dither-related issues in the converted files?

If applying dither was necessary, then I'd better follow the more laborious conventional procedure: to create a 24bit/96kHz session, to add the Hi-Res files as new tracks, to apply dither and finally bouncing each of the tracks with CD-quality bouncing options. But, you see, this would be a bit more annoying. That's why I decided to directly convert the files through the Importing Audio file manager.

What's your ideas?

Thank you!

[albee1952]

Not sure what happens when converting files from 24 to 16 bit on import, BUT, if you drag the files into a 21 bit/96K session and then choose Export Clips as Files, you can select 16 bit/44.1K and Pro Tools WILL automatically add dither as it converts and exports(no BTD required)

[michele.bartolettistella]

Originally Posted by albee1952

... if you drag the files into a 21 bit/96K session and then choose Export Clips as Files, you can select 16 bit/44.1K and Pro Tools WILL automatically add dither as it converts and exports.

Really interesting, and useful. Great to learn that this way PT adds dither automatically.

Not so with bouncing, instead. When BTD, indeed, the PT Reference Guide warns: 《Please add dither!》



Thank you.

[mjslakeridge]

I think albee1952 is right on this one. Just make sure the session you set up to import the tracks is the same sample rate and bit depth as the music files you purchased. Because I don't think dither is applied when converting imported files and by that time they would already be at 16bit, 44.1K, so applying dither when doing the bounce wouldn't accomplish anything. I thought there was a global setting somewhere in Pro Tools where you could select the type of dither to apply when exporting Clips (but I am on an old version so something may have changed).

[albee1952]

Indeed^^^there is a spot in Preferences where you can select which dither will be used automatically, so do make sure that something is selected there(if none is listed, then probably none would be applied on export, which you do want)

[michele.bartolettistella]

Originally Posted by mjslakeridge

[...] I thought there was a global setting somewhere in Pro Tools where you could select the type of dither to apply when exporting Clips [...]

Originally Posted by albee1952

[...] there is a spot in Preferences where you can select which dither will be used automatically, so do make sure that something is selected there [...]

Oh, thank you.
But I couldn't find the option about Dither in Preferences. So I searched the Help for details, and found the following informations:

When you export clips to a lower bit depth, Dither (with or without Noise Shaping) is applied as shown in the following table:

Dither and Noise Shaping with Export Selected dialog

Bit Depth                     Dither  Noise Shaping 

32-bit float to 32-bit float   Yes         Yes 
32-bit float to 24-bit         Yes         Yes 
32-bit float to 16-bit         Yes         Yes 
32-bit float to 8-bit          Yes         No 
24-bit to 32-bit float         No          No 
24-bit to 24-bit               No          No 
24-bit to 16-bit               Yes         Yes 
24-bit to 8-bit                Yes         No 
16-bit to 32-bit float         No          No 
16-bit to 24-bit               No          No 
16-bit to 16-bit               No          No 
16-bit to 8-bit                Yes         No

The Dither used for any conversion is the Avid Dither plug-in (with or without Noise Shaping enabled).

So how could I setup the dither? What is the so-called "Avid Dither plug-in"?

[mjslakeridge]

Hello Michele:
Go to Setup, then Preferences, then the Processing tab. Look in the Audio Suite box and there should be a place right near the Buffer Size option to check "Use AudioSuite Dither". Under that you can select the dither plugin to use and the bit depth.

Again, I am using an older version of Pro tools, so the settings may have changed slightly for your version.

[michele.bartolettistella]

Thank you mjslakeridge.

Unfortunately, I can't find this option in my Pro Tools 11.

Dither.jpg

Audio Suite provides two dither plug-ins. So it would be important to know what of them PT applies when exporting a clip as a file from the clip list.

[mjslakeridge]

Hmmm, Looks like they changed the setup options on newer versions of ProTools. Maybe someone here with PT 11 or newer can help find where to set the dither options.

[michele.bartolettistella]

The issue has been rather debated, elsewhere.

• PT dither question
• PSA: Pro Tools automatically dithers when exporting to a lower bit rate. And you can't stop it.
• Does the dither used in the conversion follow the session processing preference?
• Is Dither applied when Exporting audio from a Pro Tools session?

***

Anyway, apart from the CD burning. Suppose I only want to convert my Hi-Res files in Mp3: I usually opt for a Variable BitRate (V2).

This case, I don't need to open Pro Tools: with freeac converter I can directly convert the 24/96 wav in Mp3.

These Mp3 are marked as "48kHz" files, while if I came from 16/44.1 files, they would be "44.1kHz" files; I noticed that such a different sample rate wouldn't affect so much the files dimension, though. The two types of Mp3 are almost equal in terms of MB (if the content is the same, of course), and it seems that my portable Mp3 player can read the "48kHz" Mp3 without problems.

But, I wonder, should I add dither also in this encoding process?

Wav 24bit/96kHz -> Mp3

Here, as I said, there's apparently no passage from Wav 24bit to Wav 16 bit.

Sorry if a little Off Topic!