# Changing frame rate with VSE

Hey guys. I’m trying to convert a video with a frame rate of 59fps to 12fps using VSE, followed by converting the original video to an mp3 and syncing it with the 12fps video.

I followed this guide from the blender wiki:

Changing video frame rates

You can use the speed control to change the frames per second (fps), or framerate, of a video. If you are rendering your video to a sequence set, you can effectively increase or decrease the number of individual image files created, by using a Global Speed value less than or greater than one, respectively. For example, if you captured a five-minute video at 30 fps and wanted to transfer that to film, which runs at 24 fps, you would enter a Global Speed of 30/24, or 1.25 (and Enable Frame Blending to give that film blur feel). Instead of producing 56030=9000 frames, Blender would produce 9000/1.25=7200=56024 frames. In this case, you set a Sta:1 and End:7200, set your Format output to Jpeg, 30fps, and image files 0001.jpg through 7200.jpg would be rendered out, but those images ‘cover’ the entire 9000 frames. The image file 7200.jpg is the same a frame 9000. When you read those images back into your film .blend at 24 fps, the strip will last exactly 5 minutes.

Using the calculation 59.94/12 = 4.995 (the value for the speed control), I managed to output a 12fps video. However, the original video has a duration of 11:37, whereas the 12fps video has a duration of 11:36. I later saw that the speed control effect was only allowing for a multiply speed of 4.99, instead of 4.995. I assume that 0.005 is what’s causing the ± 1 second difference.

Will this difference in duration cause a problem when I want to sync the sound? If so, is there any way to correct the duration? Perhaps adjusting the frame rate of the mp3?

It’s quite a mouthful but I don’t quite see a solution. In any case, any assistance would be greatly appreciated!

I’m afraid that Blender can only add or subtract whole frames (integer frames) and does not perform any frame blending or interpolating, to be more accurate. So you won’t be able to arrive at your exact frame count. as for sync I guess that will depend on the nature of your sound / vision relationship. Speech on camera may well seem off after a minute or 2.

I decided to sync the two and see what I got. Happy to report that the final video came out well. Could be that the duration was only a few frames off, but at 12fps the difference is scarcely noticeable, even after 8 mins.