On Fri, 13 Oct 2023 19:10:33 +0200 Andreas Rheinhardt <andreas.rheinha...@outlook.com> wrote: > This design has several drawbacks: > 1. It adds stuff that will only be set by a tiny minority of AVCodec's > to all of them. > 2. It is based around the underlying assumption that the set of > permissible states (tupels) is a cartesian product of a set of color > spaces, a set of color ranges etc. This is wrong: E.g. VP9 disallows > limited-range RGB (it is syntactically impossible to set the color range > when using RGB color space). > 3. I don't see how the MJPEG encoder behaviour where the valid formats > de facto depend upon strictness can be encoded in this way; isn't the > aim to get rid of the necessity of the workaround in ffmpeg cli? > > 1. and 2. suggests using some form of function that returns a list of > supported tupels; if said function uses an AVCodecContext* parameter, > said list can depend upon the state of the AVCodecContext given to it, > thereby solving 3. to the extent that one can get the supported > combinations given AVCodecContext options (but I do not see a good way > to signal which options modify the supported combinations).
There are two other designs I can think of: 1. Enumerate all possible combinations as a list. To avoid combinatoric explosion, setting any field to 'UNSPECIFIED' implies no restriction on that field. So the default (no list) would be equivalent to a list with a single entry containing values of UNSPECIFIED for every entry. 2. Provide a single function which merely checks if a given combination is supported or not. #2 would work for the short term but runs into the same risk of exponential explosion if we need to start finding a common format between different filters. So maybe #1 is the correct approach here. It would also simplify extending the filter API, as we would only need one set of list managing/merging/compat testing boilerplate for all of the colorspace metadata. I will try implementing #1 on a separate branch. _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
