Results tagged “MJPEG Tools” from Stream #0

Real World Open Source Video Editing

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A short while ago I wrote a review about Open Movie Editor. Essentially this review was written after a couple of hours testing various video clips and assessing the functionality within OME. Now, I can write about what OME is like on a real editing assignment.

Recently I was given a DVD full of PAL DV material and asked to create a compilation from the individual clips. A fun little project that should only take a day or two. Open Movie Editor was the obvious tool for the job.

The good news I can report is that even after 10 to 12 hours of constant video editing, OME is still a very stable piece of software. I only managed to induce two crashes - once when trying to undo multiple edits in a row and once when vigorously moving clips around on the timeline. Other than that, Open Movie Editor was easily up to the task.

I'm not an advanced video editor, happy within my comfort zone using something like Adobe Premiere, but also not using all the intricate features. However, Open Movie Editor does still lack a few basic features, that would have greatly increased my productivity. Changing playback speed of a clip is not possible within OME. I needed to change the framerate of target clips using FFmpeg and mjpeg tools to achieve this effect. While fade transitions are easy enough, I'm sure they could have been even quicker if such a function was built into OME. Precise frame editing, for splitting clips for example, would also make life easier.

There are some really nice features in Open Movie Editor though. Audio automations are a breeze, the media browser window provides easy access to your video library and the list of render options is quite vast - dependent on FFMpeg, Libquicktime and other shared video libraries.

So what did I produce in my 12 hours of work? A fun 4 minute clip, which is still a little rough around the edges, but generally a good laugh. Here's a link for your viewing pleasure:

http://kapitalmototv.co.uk/play-183-0.html

Edited in Open Movie Editor, with some clip transformations using FFmpeg and mjpeg tools. Follow this with final transcoding to x264, again with FFmpeg for more finite control, and you have an Open Source Editing project.

The Kapital Moto TV site uses open source products where possible. The server runs on Debian Etch, the site is served with Apache, built largely with PHP and data is stored in a MySQL database. Content is a mix of QuickTime generated H.264 and FFmpeg generate x264 video files. The Flash player is not open source, but is free as in beer.

Unfortunately my Linux based non-linear editing tool of choice, Open Movie Editor, doesn't currently support directly altering video playback speed. For example, if you wanted a portion of your new compilation to run at 200% of original recorded speed, it can't be done within OME. This exact functionality was something I needed for an existing editing project.

After some thought and investigation, such changes can be achieved through using a combination of FFmpeg and yuvfps, which is part of mjpeg tools, to alter the framerate of the desired footage. If your original file is PAL based, with a framerate of 25fps, changing the framerate to 50fps will result in the video running twice as fast, for half as long.

I didn't initially have mjpegtools installed, but on my Debian based system this was easy enough with
sudo apt-get install mjpegtools
Next, the input video needs to be converted to yuv4mpegpipe format, passed through yuvfps and output to a new avi file. Here's the command line I used to create a clip at 50fps:

ffmpeg -i input.dv -f yuv4mpegpipe - | yuvfps -s 50:1
-r 50:1  | ffmpeg -f yuv4mpegpipe -i - -b 28800k -y output.avi

Change the 50:1 ratios to whatever framerate you require. e.g. 100:1 for 100fps. Be sure to set the output file bitrate to a relevant quality level. Omitting this flag will result in a poor quality AVI output file by default.

The resulting AVI file was easily played back with Totem, and handled on the timeline admirably by OME.

Thanks to Victor Paesa on the FFmpeg mailing list for pointing me in the right direction.

Some other options to investigate include the new Libavfilter for FFmpeg and converting the original footage to a raw data file, which will lost the audio.

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