[MPlayer-dev-eng] "expand" filter has a problem handling certain widths

[Chris Gahan]

= Summary =

I've discovered a bug in the "expand" filter that I'm unable to fix. I've looked at the source, but it's not obvious to me what the problem is. (I'm using an mplayer SVN build from 2008-09-28, revision 27668.)

Here are some cases that illustrate the bug in action.


== Case 1: Expand width by odd number of pixels  ==

You try to expand the video by an odd number of pixels, the whole video becomes sheared.

Sample clip -- http://chris.ill-logic.com/files/expand_bug/odd_width.avi
(created with: -vf expand=-621:0:0:0)


== Case 2: Even width, bmovl overlay ==

If you specify an even width that's not a multiple of 16, the overlaid bmovl image's chroma plane becomes sheared. The rest of the video is fine.

Sample clip -- http://chris.ill-logic.com/files/expand_bug/bmovl_two-pixel-grid.avi
(created with: -vf scale=640:480,expand=-620:0:620:0,bmovl=0:1:/tmp/fifo)

Overlaid image -- http://chris.ill-logic.com/files/expand_bug/bmovl_two-pixel-grid.jpg


= Followup =

Any advice would be appreciated. :)

---
Chris