timothy's Journal: How to rotate AVI files using Avidemux

How to rotate an AVI file:

I take little videos with my Casio digicam, including of note the crazy stories that my ueber-smart niece tells about ghosts, goblins, vampires etc. However, when my videos are taken in portrait rather than landscape mode, it's a bit of a pain -- it's simple to rotate *still* photos (many options exist for this, including the image viewers built into Gnome and KDE, as well as larger hammers like GIMP and ImageMagick), but for AVIs, things get uglier.

With some googling on phrases like "rotate AVI linux," I gleaned that the tool praised most copiously online for rotating AVI files is ... VirtualDub. Which doesn't run on Linux. However "virtualdub for linux" led me to believe that the closest thing going in the Linux world is Avidemux, a piece of software which I've used for simple editing in the past, but which I didn't have installed yet on this system, and which I wasn't sure could rotate AVI files. I promptly apt-got it through synaptic, and checked the Avidemux.org site, and there found that there was indeed a filter to rotate AVI files, though the page where I found this was vague on where to find or how to use this filter.

Here's the where and how, for the easily frustrated (like me):

1) Install Avidemux on your Linux-based system, if it's not already there. Apt-get, yum, portage, whatever rocks your boat and works for your system :) Avidemux is about as simply designed as it can be to do the things it does -- no interface is truly intuitive, but Avidemux does a good job of stripping things down to essentials.

2) Have an AVI file ready that you want to rotate; open it and play just to make sure that Avidemux will indeed see it happily. Being uselessly paranoid is one of my hobbies, so I usually work with a copy of the actual video clip, even if (as I am assured) nothing will be done harmful to the source material. Eh, easy to delete extra copies later. Now, things get confusing, but not too badly.

3) Looking at your Avidemux screen after opening the file, you can see your video clip, and some info / options in the sidebar to the left of it. (Little sections for Video, Audio, and Format.) Rather than "copy" (the default), change the video option to ... well, I am not sure of the benefits / drawbacks of using any of the several available formats; I picked Xvid4, and it worked fine for me. You may well know whether and why to choose a different one. Similarly, I chose Ffm AC3 for the Audio. Format remains AVI.

4) Now that you've changed it from "copy" to something else, the "Filters" option in the Video section is no longer grayed out. Click on it, and you'll get a mysteriously mostly-blank box with some options on the side. Click "Add" -- a list of available filters will now be displayed, and the one you want is "rotate," toward the bottom. Highlight that option, and then click "OK." Now a little window will come up offering a frame from the movie and a slider above it with values going up to 270. For the way I typically hold my camera (shutter button on top, lens bottom), 270 is the right angle, but slide that slider until things look right for you, then hit OK. Now that formerly blank window has the "rotate" filter listed in it. Hit OK again in *that* window.

5) Now, hit Control-S to save your video; Avidemux will ask you to supply a file name to which it will save, and the rotation will be applied to this new file. It will take a few minutes (depending on speed of computer and size of file), but if all goes well you'll now have a video file oriented right-side up, located in your home directory. Yay for free software!

Note that this process involves recompression; for the low-res videos I'm shooting on my hand-held digicam mostly as funny mementos, this is regrettable but forgivable. It actually has an advantage, too -- the resulting file is much smaller than the original without *much* degradation. As with any other editing, the software can't make up for what was lost before the image was committed to hardware. And I'd rather have a correctly-oriented video of slightly lesser quality than a 90-degree neck injury.

Hope this is useful!