session sample rate HELP

[sonora]

i have a session that was recorderd on a system with an external clock. the clock was set to 44.1K, and the session to 48K. is there anyway to fix this so it will play correct on an system using the internal clock? i'm on OS X pro tools 6.9.

[mampam]

From the Support Answerbase:
This is often caused by creating the session at the incorrect sample rate - for example, creating a session at 44.1k and then transferring tracks in digitally from an ADAT or some other device that has a clock set at 48k.

The problem with this is that the audio files have been 'tagged' at the incorrect sample rate - in the case above the audio files are 48k files, but are tagged at 44.1k. When you are no longer clocked to the digital source (by turning it off or switching Pro Tools back to 'internal' clock), the files will play back at the incorrect speed (sample rate).

Here are a few methods for correcting this problem:

If you are using Pro Tools 6.x or higher you can use the built in Digibase to correct the sample rate. Launch Pro Tools and go to Windows>Show Workspace. In the Workspace window locate the audio file(s) that need to be corrected and under the Sample Rate column, change the sample rate to the correct sample rate for the file.

There is no known solution for Windows users running versions of Pro Tools prior to 6.x.

If you are running a version of Pro Tools prior to 6.x and are on Mac OS9 you can use an application called ResEdit, which is freely available at:

http://www.resexcellence.com/support.../resedit.shtml

1. Launch ResEdit and go to File>Open
2. Locate the audio file that needs to be fixed
3. You will get a window with 3 (or more) boxes. Double click on the one marked 'STR' which will show you the resource string for the file.
4. Look for the line labeled 'Sample Rate' and change the sample rate to the correct sample rate for the file (if it's 48000.00000, change it to 44100.00000 and vice versa, assuming you're working with 44.1 and 48k files).
5. Save the file and repeat until you've fixed all the files.
6. You will then need to create a new Pro Tools session at the CORRECT sample rate and choose 'Import Session Data' from the original session.



Platform: OS X, Mac Classic, XP Home, XP Pro *** ID: 28146*** Created: 05/03/2004

[minister]

i have made this mistake more than once! i never looked in the answerbase. that's great, mampam!!

however, i am wondering about his situation. if you simply change the SR in a text way, what does he change it to? it probably DOES say 48k. but it was made at a 44.1k clock rate. does this method solve the problem? (i am asking in an i don't know way, not a you are worng way. 'cause i want to know.)

what i have done is record the file out ANALOG to another device (like a DAT) and then re transferred it. it would be nice to know that there was a simpler, quicker, method.

[Shawn Simpson]

Article on this topic.

[Redmann]

2 things to mention...

1. Manually changing the sample rate in the Workspace is not possible if the audio file format is .aiff. However, if you export all the audio from ".aiff" to ".bwf", it will let you change the value.

2. What is being listed in the Workspace is the "tagging" of the file. The audio file's sample rate will not change. You are simply informing Pro Tools what sample rate the audio is at. When you look to the audio file, if it says 48000 you can type in 44100. Then, create a new session at the proper sample rate, go to the file menu > Import Session Data and call up the original session and import all the tracks from the original session (48k) to the new session (44.1k). Now the session and audio file's sample rates will match.

Hope this helps clear things up.

[Chief Technician]

You could also get a copy of Soundhack through versiontracker.com, and use it to change the header data to indicate the proper sample rate.

[minister]

hi shawn,

thanks for the link. i went there and tried this trick. but it didn't work. OR, it is incomplete.

i happened to have this goofed up session on my system still. session setup as 48, but my clock was at 44.1 (i know, but, it happens). this is the same problem as the original post. i created a NEW 48k (which is the correct sample rate) session according to the instructions. i went to "Import Session Data", and went to the bad session, imported the track, without SRC...and, it sounds exactly the same. too fast. this method did not work.

btw, i use an external wordclock and a sync i/o

what am i doing wrong?

on the other hand, HERE IS MY SOLUTION:

create a new 48k session. import the track from the OLD BAD SESSION, and apply SRC, BUT tell, PT that the source is 44.1 and convert it to 48.

this works.

[Shawn Simpson]

I've never tried this with the external clock still engaged since it usually manifests itself after the session has been removed from the location where the clock was in use. Try turning off the clock and give it another try.

[minister]

hi shawn,

well here is the thing. if i retry the method with the clock turned off and the session setup window setup to 192-internal, here is what i found:

this is the KEY, but the first statement is confusing: Create a new session with the correct sample rate. For instance, if your audio is playing fast when on internal clock, you need to make a 44.1kHz session. If it plays too slow, you need a 48kHz session.

creating a new session with the correct sample rate (48) does not yield the right result. creating a session with the wrong sample rate (44) does give the right speed. the KEY above is the statement about too fast or too slow.

So, even switching to internal, i get the same problem. of you follow the too slow, too fast comments above, you can get the right result. but, in my situation, then i would have to go from 44.1 to 48,. to get where i want to go. ...in that case, i stand by my earlier method of importing the file, applying SRC and telling PT that the source was 44.1 (clock on or off)

or, shawn, or someone else, can you explain to me what i am doing wrong in attempting shawn's method?

[Shawn Simpson]

It's totally possible that I'm not saying what I'm trying to correctly, so I wouldn't be surprised.

The idea is that if you have a session where the external clock was set to 48k and the session to 44.1, the audio you're recording is actually 48,000 samples per second and that's what PT will play at while the external clock is operating. When the external clock is removed, the internal clock will start playing 44,100 samples per second. That will yield an apparent slowing down of the audio, right?

The statement for creating a session at the correct sample rate would mean you should create a session with the sample rate your audio was actually recorded. In the example above that would be 48k. If I import the tracks from the original session and turn off the SRC options, I would have a session operating at 48k referencing audio with 48,000 samples per second, which would make the playback run correctly.

I've done this a few times in the past, but not in a while. I'll check back on my method when I get a chance and see if there's some step I'm missing. It's not unthinkable that I'm just flat wrong.