New submission from Kevin Murray <kamur...@nds.com>: I believe there is an issue with the Chroma downsampling when going to 4:2:0 with interlaced pictures.
Simplest example is a frame picture containing interlaced lines of alternating red and blue (e.g. in a ppm). When encoded with mpeg2video or libx264 the chroma is smeared and averaged. Forcing subsampling to be point or decimation causes one field's chroma values to be discarded. A hack to initFilter in swscale.c to generate double sized filter with alternating zeros, and correct offsetting to maintain field chroma polarity start essentially corrects this (though I'm seeing some banding of the chroma on each field I would not expect). (FFmpeg version SVN-r18800; libswscale 0.7.1) ---------- messages: 5517 priority: normal status: new substatus: new title: Believed incorrect chroma subsampling on interlaced 4:2:2 to 4:2:0 type: bug _____________________________________________________ FFmpeg issue tracker <iss...@roundup.ffmpeg.org> <https://roundup.ffmpeg.org/roundup/ffmpeg/issue1093> _____________________________________________________
