Attached is a patch that implements PAFF in H.264. I don't expect this to be accepted right away, due to size and complexity, but I want to get it out there for review and for people to try out and comment on. It is working stable for me on a number of samples, including ones that mix PAFF with progressive and/or MBAFF. Basic overview of how it works: 1. Fields are decoded and deinterlaced. 2. If non-paired fields are encountered, they are not output, but are used for reference if so marked. 3. Reference lists are kept as they were before, but now may also contain unmatched field pairs. Reference list construction splits field pairs out to fields as needed. There is a major shortcoming/known issue with this patch; it disables the error concealing calls for field pictures. This is because the error concealer needs slices to be contiguous regions of the picture buffers. I'd appreciate input on how best to augment the error concealer to handle interlaced slices (or if I am just missing something....) Also interested in hearing how this should be split into smaller patches (I know that at least the addition/changes to header documentation should come out). -Jeff