I have a bunch of videos recorded from a Samsung Galaxy S6. They all have a resolution of 3840x2160 and are supposed to be at 30fps. The weird thing is, some of the clips have video segments twice the length of the audio. In Blender my project's framerate is set to 30fps.
Looking at the source files in VLC, all the video framerates are about 30fps. Why is it that some of the files imported have video segments twice the length they should? For example, the video segment will be 400 frames, and the audio will be 200. I can set Blender's expected frame-rate to 60, which causes the a/v to line up. But then the video plays back poorly (since it was not 60fps to begin with, something is messed up).
Note the following information reported by VLC.
Codec: H264 - MPEG-4 AVC (part 10) (avc1) Resolution: 3840x2178 Display resolution: 3840x2160 Frame rate: 29.981651 Decoded format: Planar 4:2:0 YUV