Should I convert non standard frame rates?

[BrandoL10]

Hello,

I am currently editing videos originally shot on an iPod Touch 4G. All of them have really strange frame rates (29.09, 28.14, 27.96 etc) and I have no idea how to handle them. I use iMovie '11 and export using quicktime. When I set the custom frame rate in the export settings, the final export is always slightly off (29.09 > 29.1). Is this an issue? The intended delivery platforms are YouTube and DVD. I know when exporting for DVD, the frame rate needs to be converted to a standard frame rate so it's compliant with the DVD spec, but should I when exporting for YouTube? If so, which frame rate and what program should I use?

[LigH.de]

Most of such videos may have a variable frame rate (VFR), means, they play faster in some scenes and slower in others during the same clip. You won't enjoy converting them when most converters assume a constant frame rate for all clips. Forcing them to a constant frame rate will mean video distortions of one or another kind (stuttering or blending).

[BrandoL10]

Ok, so what should I do with these videos upon exporting? Is it even possible to match the original frame rate on export?

[LigH.de]

There is no "one original frame rate" for the whole movie in case of variable frame rate. The term "variable" should explain that... Every frame may have a different duration. To handle such material properly, you would have to extract the timestamps of every frame before conversion, and restore all the timestamps in the destination format, if that format supports VFR at all; DVD does not, here you would have to resample the video to the target framerate (in case of AviSynth, use source filters with explicit fps parameters; I have no clue about iMovie), which will probably mean some repeated and some deleted frames. Please search other threads for more details about handling VFR.

[hello_hello]

I don't use either itunes or imovie but frame rates such as 29.09, 28.14, 27.96 etc seem to imply a "target" frame rate of 29.970fps, but frames have been dropped along the way, meaning others display for longer than their usual duration, reducing the average frame rate. You might find converting to a 29.970fps constant frame rate simply duplicates frames to replace the "missing" ones and it'll look fine. What frame rate are you specifying when you export? Not having ever used imovie I've no idea what it can do.

I assume if you're nearly there anyway, 29.970fps would be the best frame rate to aim for, for NTSC DVD compatibility, but given you're in Australia.... can you choose the frame rate to record? PAL DVDs are 25 progressive fps (50 fields per second interlaced), although most PAL DVD players will play NTSC DVDs so maybe it doesn't matter.

[BrandoL10]

Upon further inspection through MediaInfo, it appears the frame rate maxes out at 33.333fps(?). I've attached the information here. Every other video also seems to max out slightly above 30fps. When exporting through quicktime, any frame rate can be specified. I didn't know I was dealing with VFR, so I chose to use 29.09 at a CFR. It came out at 29.1 (rounded up?). There is no option to export at a VFR.

In my experience, I've never had any compatibility issues with playing back NTSC video (excluding region locking, of course). I shouldn't have any trouble using 29.970fps as my standard frame rate, in that regard.

[BrandoL10]

Sorry to bring this thread back up, but I'm sill not clear on what I have to do. Any further advice would be greatly appreciated.