Applying SRC changes file length

[Mick Boggis]

Have been hit by a weird one since yesterday pm.
When importing audio and using Apply SRC on a 1min 54 sec file, source sample rate 44100, destination sample rate 48000 and using Tweak Head quality I end up with a file length of 2min 04 seconds..
However if I import the file not using SRC the file is imported correctly.
Am using HD 8 Version 8.0.3 cs2.
Any thoughts on this truly gratefully accepted....
Thanks from one very frustrated Friday afternoon Mick

[Serge Perron]

There are two different processes that involve sample rate conversion. One changes the length of the file, the other doesn't. The process you use depends on the application.

if I import the file not using SRC the file is imported correctly.

That's the way to go for your application. If you want to import a 44.1K file into a 48K session without changing the length of the file, you select the convert option for that file without SRC. For example, if you want to import from an audio CD to a 48K session. Pro Tools detects the 44.1K source sample and does the sample rate conversion from 44.1K to 48K automatically. I don't know if this type of conversion can be done correctly with other than standard sample rates of 44.1 or 48.

If you want to change the length of the source file while importing, use SRC. For example, SRC is used to change a file from film to PAL speed. In that case, you would specify the the desired sample rate of 50000 (48K X 25/24).

So the 44.1 to 48K SRC conversion you did involved both processes and predictably resulted in a longer file: 114 sec. X 48/44.1 = 124 sec. = 2 min. 4 sec.

Serge

[Ian Palmer]

Hey Mick,

I'm agreeing with Serge. If I import say music from CD I just drag in the tracks or choose Import Audio.

Most of my work is for the international markets so every mix I do ends up in 24p, NTSC and PAL. I use the SRC to convert my stems to whichever format I need and yes it does change the length of the file (the pitch too which makes all our PAL versions sound like Chipmunks to my ears).

Sometimes automatic processes are a blessing, sometimes not.

Ian

[garret]

I can see what you mean Mick. It works fine here for me. I have a feeling the file your importing may be corrupt or have an incorrect sample rate stamp.

Serge

If you are in a 48k session and want to import a 44.1k file you have to sample rate convert in order to play at the right speed. I think you are confusing two things here. If you want to change the speed of a file you will tell protools it is a different sample rate than it is in order for the speed change to happen

[Mick Boggis]

Thanks very much for that guys, am obviously not functioning at my best today, will now give myself a good ticking off.
Ian am still keeping my ears open for you...
Have a great weekend
All the best
Mick

[Serge Perron]

Serge

If you are in a 48k session and want to import a 44.1k file you have to sample rate convert in order to play at the right speed. I think you are confusing two things here. If you want to change the speed of a file you will tell protools it is a different sample rate than it is in order for the speed change to happen

Thanks garret. My turn to give myself a good ticking off.

To correct what I said earlier: When using the IMPORT AUDIO dialog to import 44.1K audio into a 48K session, in order to preserve the duration and pitch of the original files, the files must be selected with the CONVERT option, in which case the APPLY SRC option is automatically checked and the SOURCE SAMPLE RATE is automatically set to 44100.

As Ian mentioned, simply dragging the 44.1K files into the 48K session accomplishes the same thing.

[Ian Palmer]

Cheers Mick, I appreciate it.