Custom thumbnail/media sizes for video

[Jonas Öberg]

It would be very useful to be able to generate any number of thumbnails of different sizes from media uploaded, especially videos. This is partially related to #1042, as sharing a link to a video on MediaGoblin to another site would be helped by being able to convey appropriately sized media previews. The current thumbnails are useful for the MediaGoblin gallery, but it would be beneficial to be able to generate additional thumbnails with higher resolutions.

With the attached patch, I've taken some steps towards that, but I know far too little about MediaGoblin to make much progress beyond this. It tries to implement some sort of generic approach to generate images from videos, and supports the old thumb functionality as well a new "share" image, which is a higher resolution image. But both "share" and "thumb" are rather hardcoded, and it would be useful to be able to configure these sizes without modifying the code. I also don't know what else in mg is affected by this.

[Jonas Öberg]

Code diff