h.264 - FFMPEG (libx264) "height not divisible by 2"

Question

I am trying to encode a .mp4 video from a set of frames using FFMPEG using the libx264 codec.

This is the command I am running:

/usr/local/bin/ffmpeg -r 24 -i frame_%05d.jpg -vcodec libx264 -y -an video.mp4

I sometimes get the following error:

[libx264 @ 0xa3b85a0] height not divisible by 2 (520x369)

After searching around a bit it seems that the issue has something to do with the scaling algorithm and can be fixed by adding a -vf argument.

However, in my case I don't want to do any scaling. Ideally, I want to keep the dimensions exactly the same as the frames. Any advice? Is there some sort of aspect ratio that h264 enforces?

Answer 1

The answer to the original question which does not want to scale the video is:

-vf "pad=ceil(iw/2)*2:ceil(ih/2)*2"

Command:

ffmpeg -r 24 -i frame_%05d.jpg -vf "pad=ceil(iw/2)*2:ceil(ih/2)*2" -vcodec libx264 -y -an video.mp4 

Basically, .h264 needs even dimensions so this filter will:

1. Divide the original height and width by 2
2. Round it up to the nearest pixel
3. Multiply it by 2 again, thus making it an even number
4. Add black padding pixels up to this number

You can change the color of the padding by adding filter parameter :color=white. See the documentation of pad.