Theora source videos may have an encoded frame size that is different from the represented picture size; when transcoding, the transcode should keep the same picture area, regardless of what the encoded frame size was.
Example: this funny-sized video https://commons.wikimedia.org/wiki/File%3AChocolate_cake.ogg is encoded with a non-null picture crop size and position, and the area outside the picture is encoded as solid green thus stressing this bug and making it very visible.
- https://upload.wikimedia.org/wikipedia/commons/a/a6/Chocolate_cake.ogg [Note! Firefox is also buggy and crops this file incorrectly. Play in VLC for proper playback example.]
- Transcode should have picture or black bars up to the edge at all times
- Transcode has several pixels of green bar around the picture
This is possibly a bug/feature/misfeature of libav/ffmpeg/ffmpeg2theora...?