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[FFmpeg-devel,0/3,RFC] EXIF overhaul

Message ID 20240213212456.167386-1-leo.izen@gmail.com
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Series EXIF overhaul | expand

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Leo Izen Feb. 13, 2024, 9:24 p.m. UTC 
A few notes:
- This includes an avpriv_ removal, so it won't be able to be merged
  until the ABI is bumped. Alternatively, I could add that avipriv_
  back in as a wrapper around the actual API so it's not a blocker,
  and then we can remove it when the time comes to bump the ABI.
- MakerNote inside TIFF files are not handled by this patch. I don't
  have any samples that lets me reliably special-case them based on
  manufacturer. MakerNote is, by spec, a binary blob, but in practice
  it's often a TIFF IFD, with arbitrary data before the IFD starts
  and arbitrary semantics on whether its IFD-offsets are relative to
  the start of the TIFF header or the start of the MakerNote. The lack
  of samples makes this hard to work around. See [1] for more details.
  Note that [1] links [2] but [2] is a deadlink.
- We attach the EXIF buffer as-is from mjpeg, webp, or other files that
  treat it as a blob, but we still need to parse it in order to determine
  the display matrix orientation side data. If there's a better way to
  handle this, please suggest one.
- AVFrameSideData must be flat, so we can't parse it and store an
  AVDictionary * pointer in its place, as convenient as that would be.


[1] https://exiv2.org/makernote.html
[2] http://www.exif.org/samples.html

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                  | 267 +++++++++++++++++++++++++++--
 libavcodec/exif.h                  |  21 ++-
 libavcodec/exif_internal.h         |  41 +++++
 libavcodec/mjpegdec.c              |  96 ++---------
 libavcodec/mjpegdec.h              |   2 +-
 libavcodec/pngdec.c                |  35 ++++
 libavcodec/pngenc.c                |   4 +
 libavcodec/tiff.c                  |  19 +-
 libavcodec/tiff.h                  |   1 +
 libavcodec/webp.c                  |  38 ++--
 libavformat/avidec.c               |   4 +-
 libavutil/frame.c                  |   1 +
 libavutil/frame.h                  |   6 +
 tests/ref/fate/exif-image-embedded |   5 +-
 tests/ref/fate/exif-image-jpg      |  91 +++++-----
 tests/ref/fate/exif-image-webp     |  91 +++++-----
 18 files changed, 521 insertions(+), 229 deletions(-)
 create mode 100644 libavcodec/exif_internal.h