Canvas filter messes up aspect ratio
I run vlc with '--video-filter=canvas{width=800,height=600,aspect=4:3}' option, expecting it to scale the video and add black stripes below and above. Instead, it adds the black stripes and changes aspect ratio in a strange way. When I force aspect ratio to be 4:3, the video is correct.
I attach a patch that fixes this issue, but I'm not 100% sure it's correct (meaning that it could break something else). It removes some aspect ratio calculations at the end of canvas filter. My intuition is that since canvas filter simply applies scale and croppadd filters, the aspect ratio should be already correctly set by croppadd filter.
I've spotted this bug in VLC on Ubuntu 12.04 in the version from Ubuntu repositories (2.0.3 Twoflower (revision 2.0.2-93-g77aa89e)) and in the version compiled from git (2.1.0-git Rincewind (revision 07ee81e)).