Why does rotating an MP4 video quadruple file size?

[gf1701]

And can I prevent it? I'm happy that I was able to get the process to work, but I'm wondering why the file that resulted is so huge. The only change that I made (knowingly, at least) was to rotate the video 90 degrees, yet the converted file ended up about 4 times the size of the original. I did notice that the Data Rate of the original file is 26257 kbps, and the output of the converted file is 113454 kbps (not coincidentally, I'm sure, about 4x greater), but I don't know why the rate changed. Total Bitrate also increase 4x. I tried specifying the original bitrate in the Video Codec options and reconverting, but that resulted in a choppy, pixelated video that did whose bitrate did not match my specification (and the result file was 1/3 the size of the original). So is there anything I can do to maintain close to the original file size?

[Rémi Denis-Courmont]

You need to transcode, so the new bit rate can be much anything, depending on settings.

[gf1701]

So, what can I do about it?

[Rémi Denis-Courmont]

Nothing. Rotate on the final viewer.