Confused over FPS options

[trailryder42]

I'm working with GoPro videos in VS8.

In both the camera and VS, both FPS of 29.97 and 59.94 are called 30 and 60. When choosing a profile to render to in VS, for example, in a 29.97 fps profile, out to the side of the profile description it shows (30). Yet, in the fps dropdown list when making a custom profile, you can choose 29.97, 30, 59.94, or 60 fps.

Is it just that the 2 sets of fps are so close to each other they're considered the same? If so, why differentiate with so many rendering options?

A video from a Gopro shot in 29.97 or 59.94 fps, even tho the camera setting option says 30 or 60, will it be slightly out of time or phase or something if you render it in VS at an actual 30 or 60fps?

Or does the rendering process add or subtract frames as necessary?

[dtvp]

The "NTSC" HD broadcast standard is for 29.97 or 59.94 (and 23.94). It's a hangover from the days of analogue SD colour when the system needed to drop a frame to help with the colour encoding.

There are some cheaper cameras and other sources that ignore this drop frame and produce pure 30/60fps, but any decent camera will actually stick to the broadcast standard. Although this dropped frame is insignificant in terms of the viewing experience - it's only a frame about every 30 seconds - it can cause long term audio sync issues if misdetected during the editing or capture process.

Now, I can't see any project property settings for "pure" 30/60 fps, only in the mp4, MOV and AVI export settings. I assume this is for compatibility with computers, but you can't edit at those frame rates.

Most equipment manufactures use 30/60fps in the descriptions when they actually meant the broadcast frame rates. I assume this is trying to simplify matters.

So, if you are shooting with a GoPro you should chose the 29.97/59.94 options. (Actually, 29.97 is slightly out as well - it is 30fps slowed by a factor of 1.001 but that's what they have to call it as the fps is a reoccurring decimal)

When it comes to the render, if you chose 30fps rather than 29.97 an extra video freeze frame will be inserted as required. The audio and video streams should be forced into sync. Why you would need to use this setting I can only guess, particularly as VS would adjust any footage that was 30fps down to 29.97 when you put it into a project by taking a frame out every so often.

[trailryder42]

Thanks for explaining that.