Dugan Chen's Homepage

Various Things

Preparing Video for AMVs. In Linux.

I just finished watching an anime and now I feel inspired to make another AMV. This time, I want to use Linux and open source software to do it.

My sources are fansubs by gg. They’re 720p (1280×720 16:9) x264-encoded MKVs with embedded subtitles. Obviously, they would need to be converted to a format that uses intra-frame compression. A lossless format such as HuffYUV would be ideal. Because lossless video uses a lot of space, I would not convert the entire season. Instead, I would convert only the clips I need. Finally, I see no reason not to edit in 720p.

The commands to clip out the first 10 seconds of the first episode follow.

I can specify that the clip starts at second 0 and last 10 seconds:

mencoder -noskip -nosound -nosub -ovc lavc \
 -lavcopts vcodec=ffvhuff -ss 0 -endpos 10 \
 \[gg\]_Puella_Magi_Madoka_Magica_-_01_\[0557C1C6\].mkv \
 -o prolog.avi

The times (starting time and clip length) are in hh:mm:ss format, where fields that don’t actually add information are optional. For example, a clip length 00:00:10 can be shortened to 10.

This results in a clip with the correct frame rate and aspect ratio, that works perfectly in OpenShot. The commands above, of course, strip out the audio and subtitle tracks.

Because I’m starting with video that has already been processed for digital distribution, I do not have to worry about things like removing 3:2 pulldown or otherwise dealing with interlacing. The encoders at gg have taken care of that for me.

Time, now, to go through the dozens of OpenShot videos that are available. These include not only the ones on OpenShot’s project page, but also the ones on AMV Relish.