I've made some changes to the last EXIF overhaul patch I sent, notably I fixed up some bugs and added MakerNote parsing, so it should not corrupt MakerNotes that are inside TIFF files.
MakerNote is supposed to be a binary blob but many camera manufacturers treat it as an IFD (e.g. Canon) with offsets relative to the start of the file, so it has to be parsed in order to move it from TIFF to another file or it will be corrupted. I also fixed the fate tests now that pngenc.c writes eXIf chunks, so those should pass. I haven't come up with a solution that Andreas proposed, which is: > If I see this correctly, then these patches can lead to a situation > where an input packet has rotation metadata in exif which gets exported > twice -- as displaymatrix and as exif metadata side data. If the user > changes the displaymatrix (e.g. applies the transformation to the image > data and removes the displaymatrix side data before reencoding), the > exif data (that the user would probably not be aware of) would still be > there and get propagated into the output, corrupting it. Zeroing out the EXIF orientation tag upon attaching the displaymatrix is something I did consider, but it would corrupt encoding unless I also read the displaymatrix data and attach it as EXIF orientation. This isn't too hard if the Orientation tag exists but it's more difficult if it doesn't already exist. It's also not clear what to do if the AVDisplayMatrix is not in the dihedral group D4. Currently there's no code that takes an AVDictionary and writes it back into EXIF as these are not compatible structures. EXIF includes integers of varying lengths, while AVDictionary contains strings only. Leo Izen (3): various: change EXIF metadata into AVFrameSideData avcodec/pngdec: parse eXIf chunk avcodec/pngenc: write eXIf chunks fftools/ffprobe.c | 27 +- libavcodec/Makefile | 1 + libavcodec/exif.c | 394 +++++++++++++++++++++-- libavcodec/exif.h | 32 +- libavcodec/exif_internal.h | 55 ++++ libavcodec/mjpegdec.c | 91 +----- libavcodec/mjpegdec.h | 2 +- libavcodec/pngdec.c | 35 ++ libavcodec/pngenc.c | 4 + libavcodec/tiff.c | 19 +- libavcodec/tiff.h | 1 + libavcodec/version.h | 2 +- libavcodec/webp.c | 38 +-- libavformat/avidec.c | 4 +- libavutil/frame.c | 2 + libavutil/frame.h | 6 + tests/ref/fate/cover-art-mp3-id3v2-remux | 6 +- tests/ref/fate/exif-image-embedded | 5 +- tests/ref/fate/exif-image-jpg | 91 +++--- tests/ref/fate/exif-image-webp | 91 +++--- tests/ref/fate/mov-cover-image | 6 +- 21 files changed, 676 insertions(+), 236 deletions(-) create mode 100644 libavcodec/exif_internal.h -- 2.46.0 _______________________________________________ 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".
