Bit Depth, Avid to Pro Tools Workflow

[youthofbeast]

Hello everyone, I'm panicking!

I edited an 80min film in Media Composer. Two months ago I exported 5 reels into a Pro Tools session by selecting the respective sequences, clicking Send To --> ProTools --> Quicktime - Consolidate Audio.
I assigned both Bit Depth and Sample Rate to "Project," assuming that this would maintain whatever format I had been using thus far.
But now, 2 months later, and after a lot of intense sound work, I discovered that the Avid project settings were set to 16-bit, and that the files I was working from were recorded in 24-bit.
I'm guessing that this forced Avid to "dither down," and that this may have resulted in a lot of unwanted noise.

Now, my desperate question is:

Can I re-export all of the reels, this time in 24-bit audio, and relink the new files in such a way as to maintain all of the work I've done in the PT session?

[Top Jimmy]

It's tricky but it can be done. Assuming these are wav files, export the files from MC again at 24-bit and stash these in a folder. With the appropriate session open in PT, go to File>Save Copy In selecting 24-bit and choose to copy all of the audio files as wav. Once the session has been copied along with all of the wav files, quit PT. Now go through the audio files folder in the copied session and rename the 24 bit files in the folder from MC so that the same files have identical names. Now trash all of the files from the audio files folder replacing them with the renamed files from MC. When you open the copied PT session, you will get a file relink pop-up. Choose to relink manually and then find by file name only. When the links appear in the relink window, commit them and get on with your production.

If the wav files directly from MC are not interchangeable with PT wav files, an intermediate step is required to make them so. Create a new 24-bit PT session and import the files from MC. Now you can use the files from the audio files folder of this new session to drop into the converted one.

[youthofbeast]

Great, thanks so much. And can I just ask you, how necessary do you think it is to go ahead and correct this mistake considering that this is a feature film that is aiming to be screened in theaters with 5.1 surround? Is it likely that the conversion from 24 to 16 resulted in a lot of audible noise?

[Top Jimmy]

Originally Posted by youthofbeast

Is it likely that the conversion from 24 to 16 resulted in a lot of audible noise?

Possibly though maybe not directly. It comes down to how hot the original tracks were recorded and whether MC dithered or truncated when the files were exported. If dithered, there would be a low-level noise added. If truncated, the quantization noise would be correlated to the audio. The first most important test is whether or not you can discern either of these noises. Can you?

The issue you really need to weigh is what your peers would think if they knew of this. I for one know that I could successfully save all the work accomplished so far while reverting to the original 24-bit audio. So can you, and it's not as difficult as it seems.

[TommyT]

You should keep in mind that although higher sample rates & deeper bit rates of course make everything sound better. Feature films played in theaters with Dolby 5.1 employ roughly a 10 to 1 data compression, essentially your listening to a 320k bit mp3 in 6 channels.. and DTS is roughly 5 to 1.. So although more bits and samples for all your sound processing will all have a combined effect of sounding better through the mixing & dubbing process. Your final product is essentially an Mp3... Imagine if you spent a lot of time & money fixing some bad graininess , or color correcting some badly lighted shots , only to have your final output the quality of a mediocre youtube video... So you should keep this in mind when spending time & recourses on a fix that in the end may not be noticeable...

Just some thoughts ...