Rotate mp4 videos without re-encoding

https://stackoverflow.com//questions/25031557

21-12-2019
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Question

I'm looking for a way to rotate videos shot with my Nexus 4 on my Debian Wheezy sytem. The videos are shot in portrait mode and I would like to rotate them to landscape mode. Preferably the rotation is command-line driven.

I have found several previous questions which are hinting at a good solution but I can't seem to manage to get it working.

To begin with there was this question: Rotating videos with FFmpeg

But it indicates that ffmpeg is outdated and that I should use avconv. I found this question detailing the way to go forward. https://askubuntu.com/questions/269429/how-can-i-rotate-video-by-180-degrees-with-avconv

This made me using following command:

avconv -i original.mp4 -vf "transpose=1" -codec:v libx264 -preset slow -crf 25 -codec:a copy flipped.mp4

However, this is painstakingly slow (last test took me more than 6 hours for less than 3 minutes of footage) and does not result in a playable movie. I also get an error in logging output which states Mb Rate > level limit.

Is there an issue here with the re-encoding? Should I first re-encode the videos from my phone to another, more "workable" encoding before applying the rotations? Or am I missing another important point?

Solution

If you just want to change the metadata such that mediaplayers that consider the flag play the file rotated, try something like:

ffmpeg -i input.mp4 -c copy -metadata:s:v:0 rotate=90 output.mp4

as found elsewhere on stackoverflow.

OTHER TIPS

Rotation=0 fixed my issue. I started recording video in portrait mode, realized my mistake and immediately turn my phone to landscape to continue recording. My iphone had marked the video as portrait for the entire video.

ffmpeg -i input.mp4 -c copy -metadata:s:v:0 rotate=0 output.mp4

Fixed it.

FFmpeg and similar programs change the metadata even with the -map_metadata option. exiftool can read the rotation matrix and rotation flag, and since version 10.89 also write it as described below.

To get true lossless (incl. metadata) rotation, I couldn't find a solution, so I grabbed a hex editor (eg HxD) and analyzed the rotated video files.

True lossless rotation of MP4:

open mp4 with hex editor and search for vide to find the metadata of the video track
some rows above (for my files mostly 9, sometimes 12) you should see trak...\tkhd
in between there should be an @ sign (HEX 40)
in the two rows before it the rotation matrix is stored

no rotation:

00 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00
40

180°:

FF FF 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
FF FF 00 00 00 00 00 00 00 00 00 00 00 00 00 00
40

90° cw:

00 00 00 00 00 01 00 00 00 00 00 00 FF FF 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
40

90° ccw:

00 00 00 00 FF FF 00 00 00 00 00 00 00 01 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
40

Alter the file as you need it, and it should be rotated in players that support the rotation flag (most current players do).

In case your video contains stereo audio, this is obviously not switched, so in case you want the sound to match with video rotation (180°), you need to switch the left and right channels.

There are several things that you've touched on in your question:

There is almost no chance that you will able able to rotate without reencoding. The exception to that rule (MJPEG codec) has already been pointed out, but it's unlikely that you are using it, so it goes beyond the scope of this question. I will mention that the reason for this ability is that JPEG can be converted via metadata. Thus if you'll be able to find a container which has the metadata rotation, you'll be able to rotate, but none exist (or are wide spread enough) so far.
If it took your hours to rotate and reencode 3 minutes of the video, then the problem can lie on an enormous resolution. And i mean huge! Can you please provide the output of the avprobe original.mp4 so that it can be ascertained.
Libav versus FFmpeg debates are very counterproductive (you can see that by the amount of fud posted here already). Basically what has happened was a split of the project with some developers going one way and some another, the fact that FFmpeg project has managed to keep the name is just a fluke and it makes no sense to call one project original and another a fork. The differences between projects are mostly in the development style and on the philosophy. If you would characterise FFmpeg as more Open Source and Libav as more Free Software, you'd not be all that mistaken. Rational people hope that eventually the developers will come to their senses, and maybe not merge the projects, but cooperate to the larger extent. When Ubuntu came out originally, on every Debian GNU/Linux chat there were huge messages along the line of "Ubuntu is NOT Debian!!!!!!!", but now the situation has calmed down and both sides are quite happy with one another.

This answer is simply a summary of the comments provided by LordNeckbeard.