Upsample Audio Duration

[Jazzvibe]

dearon80, thanks for the insight regarding clock speed of various devices. That's not something I fully understand.

The two 48k 24 bit files came from separate video cameras, a pro camera with a line in from the board and a zoom camera with built in mic. None of the sources were sync but the audio for the first two sources do line up. The third 44.1k 16 bit source is from a zoom audio recorder w built in mic. That's the one that does not line up. I may try your suggestion of recording analog out of that zoom recorder if I can barrow it.

The audio line into the pro camera clipped badly. After trying to work with it in Izotope RX I wanted to try blending in the other sources to hear if that improved anything.

Thanks again.

[albee1952]

How I would handle this:
1-create a new blank session at 48K/24 bit
2-import the pair of 48K files onto new tracks
3-go to file>Import>Audio. Find the Zoom audio file and SINGLE-click it(so its selected in the left column ONLY.
4-Click on "Convert". This action will convert the sample rate so it matches the session.

Any time you import audio that doesn't match the session, you need to convert it(if you don't select to convert, then you get the message that the file will not play at the correct speed/pitch). Of course, you could go the other way and use a 44.1K session and convert the 48K files, but why throw away quality at this point in the process

[Jazzvibe]

albee1952 Thanks that's exactly what I did.

I previously described the message I get above the convert audio window that says PT can convert the file but that it will play back at the wrong speed.

[ehaber]

When you say that the “convert audio window that says PT can convert the file but that it will play back at the wrong speed,” that’s not what PT is actually saying. If you are attempting to import an audio file into Pro Tools that’s at a different sample rate from your project sample rate, Pro Tools says that the file “can be added directly to the current session, but it will play back at the wrong speed.” What that means is that if you use the Add button to add the file without applying sample rate conversion, the file will play back at the wrong speed. If you actually use the “Convert” button to import the file, Pro Tools will create a new wav file at the session sample rate that will have converted the audio file using sample rate conversion. In that case, the new file will not play back at the wrong speed.

Am I correct that in your 48 kHz project, both 48 kHz audio files and the sample rate converted file that was originally at 44.1 kHz are all at the correct pitch? If that’s the case, that would mean that all three files originally had header info in the wav file that was correct as to the sample rate (that is, two of the files were correctly thought of as 48 kHz files and one was correctly thought of as a 44.1 kHz file). So that doesn’t seem to be an issue.

Now since you used three independent recorders to record the audio, what you need to understand is that since each recorder had its own internal clock, each clock’s definition of how long a second actually is will vary very slightly from the other. So when you loaded the three files into Pro Tools (two at 48 kHz and one sample rate converted from 44.1 to 48 Khz), and presumably laid them out by ear so that they seemed to sync up with each other at the very beginning, because each had a different internal clock, all three could be expected to drift slightly over time from each other. So, if your two 48 kHz files don’t drift out of sync over time with each other, that just means you were lucky with those two files. The fact that the 44.1 kHz file that’s now been sample rate converted to 48 kHz does drift off sync with the other two, has nothing to do with it originally being a 44.1 kHz recording; it simply means you weren’t as lucky with that particular file (and with that particular recorder’s clock versus the internal clock of the other two recorders). Now you can try to use TCE to adjust the file that drifts, but my experience is that doesn’t work very well for that purpose and won’t sound very good. My guess is that, instead, you’ll have to listen to the three files, and as the one file that drifts, drifts out of sync, you’ll have to do many small edits to get it back in sync. Very time consuming and tricky to do, but that’s what happens when you use multiple recorders that aren’t recording using the same master clock.

[Jazzvibe]

ehaber thanks for your reply. I'm starting to understand what you and daeron80 have said about separate recording device clock speeds and the problem it can cause. I appreciate that.

The other part about PT saying it can convert the file (which is the only button option you can use to get it into the 48k 24 bit session) but that it will not playback at the correct speed, makes no sense if it actually converts the file to the correct speed. Why would that message show up? I don't understand.

[ehaber]

It's not true that the convert button is the only button option you can use to get an audio file of a different sample rate into your 48 k 24 bit session. When using the import audio function and you highlight an audio file of a different sample rate, the "convert" button is colored purple, which basically only indicates that it's the preferred method of importing as it will create a new file that's sample rate converted to the sample rate of the session. However, you can still click the Add button (which is white) instead of the Convert button and it will add the file to your session--but it will play back (as the warning goes) at the wrong speed. Why don't you try it--pick a random audio file that's not at 48 kHz and add it to your 48 kHz Pro Tools project by clicking the Add button, and then put the unconverted audio file on a track and listen to it--you'll hear that the pitch is way off.

[Jazzvibe]

ehaber, Interesting, I don't see that here at all. As soon as I highlight a file of a different sample rate the Add button changes to Convert. The only option I see at that point is Convert and the message about playback at the wrong speed comes up.

I'm using ProTools LE not HD could that be the difference here?

[ehaber]

Well, firstly, just so you know, the terms Pro Tools LE and HD don't exist anymore. What used to be called Pro Tools HD is now called Pro Tools Ultimate. And what used to be called Pro Tools LE would now simply be referred to in the software as Pro Tools (without the Ultimate designation). Now in one of your earlier posts you say that you are running Pro Tools 2021.12.0, which is the latest version of Pro Tools, on Catalina. I'm also running the same. I do have both Ultimate and regular Pro Tools--authorized on separate Iloks. When I open Pro Tools with the Ilok with regular Pro Tools authorized, the program opens as regular Pro Tools and not Ultimate. I've now tested it either way, and with both Ultimate and regular Pro Tools, when you go to import audio that has a different sample rate than the session sample rate, while Convert is purple, the Add button in white remains as a choice (and if using the Add button, no sample rate conversion will happen). Not sure why you're seeing something different--when you are importing audio, are you selecting the "File" drop down menu from the top, navigating down to "import", and then from the right hand menu that appears selecting Audio? Or are you using a different method of importing audio that I may not be aware of?

[Jazzvibe]

ehaber Thanks for reminding me, I started with Pro Tools about 15-17 years ago, version I can’t even remember, and had forgotten the name changes (and the confusing purchase options) after V 12

I may have found part of the answer to the problem though!

i had been using command-shift-I to import. Following your directions I tried the file menu drop down to import and when the window opened, this time it flickered for a very brief moment, shifted the view of the audio from the right side of the window to left, and then voila, I saw exactly what you described.

Very Bizarre! It's as if something reset itself. I suppose it's possible my eyes reset themselves but I'm almost positive it was not that way before. Previously there was only the one option, the add button that changed to convert and the audio files were to the right of the import window directly above where the audio files populate after clicking the add or convert button as oppose to above the left column where they start.

I've tested it going back to command-shift-I as well as testing in another user account and it now shows exactly as you describe every time.

With the add button showing as a separate option the wrong speed message starts to make some sense (although you have to read it carefully).

I re-imported the audio using this separate convert button and other than appearing to show a lower amplitude on screen it’s seems to be the same as what I had imported before. So it must have to do with the clock speed issue of that recording device.