I. Frame Rates

The are several frame rates that you will come across in the post production world.

The most common ones are 29.97(NTSC), 23.98(NTSC), 24(Film), and 25(PAL).  When a picture gets transferred from one speed to another the audio will have to change speeds as well (**Note: this is not always true now with some advanced video transfers, but for the sake of this tutorial I will assume traditional speed changes are taking place)

29.97fps and 23.98fps are both slowed down .1% from real time (from 30 and 24 fps respectively). This means that 1 hour of timecode is actually .1% longer than an hour of real time.  This gave birth to drop frame timecode which is used in television. I will not go into drop frame here.

PAL and Film run at the same speed as real time.  That means that an hour of timecode will equal an actual hour.

The table below shows the speed changes between the different frame rates. (please note: all PAL conversions in this tutorial assume that the picture department plays 25fps picture at 24fps or visa-versa. There are other ways to convert PAL to NTSC and PAL to Film that do not incur a speed change)

II. Examples

Example #1 Film -> NTSC
To do pull ups and pull downs in Pro Tools we use the Sample Rate Conversion (SRC) feature on the import audio window. For our examples we will assume your source and destination are all going to be 48k.

1. Make a new session at the bit depth you are working at.  In the session setup window (command – 2 on the number pad) change your frame rate to 24.

2. Open the import Audio Window (shift-command-I) and choose the file you want to pull down.

3. Press the convert button, and check the box that says “Apply SRC” this will enable the “Source Sample Rate” dialogue.

4. Scroll to the bottom of the “Source Sample Rate” dropdown and you will see a category that says “48kHz (Pull Up/Down) Choose the appropriate setting which in this case is “47,952 – 0.1% Down (film to NTSC)”

5. Click Done and it will ask you where to save the file, and then it will import into your session.  You know have a file that is 48k, but plays .1% slower than the original.

III. Throwing PAL into the mix! PAL to Film Speed

(NOTE: In PAL 2 pops are supposed to be 48frames from FFoA.  If this is done correctly, you do NOT need to cut off head and tail pops as I explain below.  I have gotten a slew of projects where that is not the case, so I use the method below.  See comments for a discussion on the topic.)

Here it get’s a little more complicated.  Before you can do the conversion you have to take off any head or tail pops.  So cut your mix to first frame of action and last frame of action (when appropriate).  Then take that file and follow the steps below.

1. Make a new session at the bit depth you are working at.  In the session setup window (command – 2 on the number pad) change your frame rate to 24.

2. Open the import Audio Window (shift-command-I) and choose the file you want to pull down.

3. Press the convert button, and check the box that says “Apply SRC” this will enable the “Source Sample Rate” dialogue.

4. Scroll to the bottom of the “Source Sample Rate” dropdown and you will see a category that says “48kHz (Pull Up/Down) Choose the appropriate setting which in this case is “46,080 – (PAL to Film)”

5. Click Done and it will ask you where to save the file, and then it will import into your session.  You know have a file that is 48k, but plays 4% slower than the original.

6.  Now you will have to pitch your files up 4% to make up for the speed change. (Note: this is only done with 4% changes as a .1% change is not audible)

7. Add head and tail pops back on the file, and you’re all set to play you PAL audio at film speed!

NOTE: When importing audio into Final Cut watch for this bug.