Archive for August 4th, 2009

The 3 ways of converting 30p to 24p

There are 3 ways to convert 60i/30p to 24p. Each one has its ups and downs. None is really ideal for all cases, so if you really need real 24p, get a real 24p camera. In detail:

1. Resampling (or motion estimation)
This is the default Sony Vegas mode when your project properties has a specific source frame rate and you export in another, or when you slow-down footage. There is a huge amount of ghosting introduced when resampling is ON. I personally always make sure that all the clips in my timeline are set to “disable resample” before I export. I suggest you do too. Vegas’ resampling is one ugly algorithm, avoid. Ghosting:

2. Drop frames
This method will drop 6 frames per second in order to convert from 30 to 24 fps. On Sony Vegas you do that with the “disable resample” option mentioned above. Other editors, use this method by default (it’s the simplest to implement). The problem of this method is that the video it produces is jerky. You see, the camera didn’t record 24 frames at 24 even times a second, but 30, and so there will be “gaps” in the motion of the video. These gaps will show up as jerky video. The good news is that many viewers never notice, the bad news is that this will still not visually feel like real 24p.

3. 25% slow down
This is my preferred method. Basically, by slowing down the playback rate by 0.800, we essentially emulate the 24p capturing process perfectly. There is no jerkiness, everything gets a smooth, dreamy look, which is very cinematic. And no, the vast majority of the viewers will never realize that the footage was slow-motion’ed! It is the perfect way to shoot music videos (using this trick), artistic/abstract pieces, and anything else that doesn’t require synchronized speech. See, this method has a drawback: you can’t resample audio with the same effectiveness as you do for video, it will sound real slow and bad (even after correcting the pitch). So basically, this method is out from the moment you want to use the audio captured along the video. You can only add music/narration during post processing, but no sync’ed speech. This method takes out the ability of shooting short movies where people have to talk on camera, but it’s good for everything else.

Showing all 3 methods visually:

My model is Emily Palen, from the band Dolorata

Here are the playback rates you need to use for the 3rd method:
60i (via interpolated de-interlacing), or 29.97 fps to 23.976 fps: 0.800
60i (via interpolated de-interlacing), or 29.97 fps to 24.00 fps: 0.801
30.00 fps to 23.976 fps: 0.799
30.00 fps to 24.00 fps: 0.800
Of course, always disable resample just before you export, on all your clips in the timeline.

Shooting a wedding

I am shooting a wedding for a friend this weekend, and along enough tapes, a second battery, and two additional HD digicams (Panasonic FX150 and Canon SX200 IS) sitting on tripods, the following Canon HV20 camcorder will be the main rig that I will be using.

JBQ will be shooting still pictures with his Canon 5D, and he will be taking care one of the two digicams (video recording must be restarted every 15 minutes, because of FAT32 limitations). I just need to find a second person at the wedding (possibly a kid) to take care of the second digicam.

Color grading of the week, Part 9

The film look is traditionally low-contrast, and low-saturation.

Picture by Raveesh Vyas, licensed under the Creative Commons “Attribution Share-Alike” 2.0 license.


Picture by Matt Lemmon, licensed under the Creative Commons “Attribution Share-Alike” 2.0 license.