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Andreas Rheinhardt a84087eaf8 avcodec/pngdec: Fix APNG_DISPOSE_OP_BACKGROUND 
APNG works with a single reference frame and an output frame.
According to the spec, decoding APNG works by decoding
the current IDAT/fdAT chunks (which decodes to a rectangular
subregion of the whole image region), followed by either
overwriting the region of the output frame with the newly
decoded data or by blending the newly decoded data with
the data from the reference frame onto the current subregion
of the output frame. The remainder of the output frame
is just copied from the reference frame.
Then the reference frame might be left untouched
(APNG_DISPOSE_OP_PREVIOUS), it might be replaced by the output
frame (APNG_DISPOSE_OP_NONE) or the rectangular subregion
corresponding to the just decoded frame has to be reset
to black (APNG_DISPOSE_OP_BACKGROUND).

The latter case is not handled correctly by our decoder:
It only performs resetting the rectangle in the reference frame
when decoding the next frame; and since commit
b593abda6c it does not reset
the reference frame permanently, but only temporarily (i.e.
it only affects decoding the frame after the frame with
APNG_DISPOSE_OP_BACKGROUND). This is a problem if the
frame after the APNG_DISPOSE_OP_BACKGROUND frame uses
APNG_DISPOSE_OP_PREVIOUS, because then the frame after
the APNG_DISPOSE_OP_PREVIOUS frame has an incorrect reference
frame. (If it is not followed by an APNG_DISPOSE_OP_PREVIOUS
frame, the decoder only keeps a reference to the output frame,
which is ok.)

This commit fixes this by being much closer to the spec
than the earlier code: Resetting the background is no longer
postponed until the next frame; instead it is applied to
the reference frame.

Fixes ticket #9602.

(For multithreaded decoding it was actually already broken
since commit 5663301560d77486c7f7c03c1aa5f542fab23c24.)

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
2022-08-23 12:21:00 +02:00
compat compat: add msvc windres wrapper 2022-08-13 14:42:52 +02:00
doc qsvenc_{hevc,h264}: add scenario option 2022-08-23 12:42:19 +08:00
ffbuild ffbuild/common: Fix CPPFLAGS applied for compiling C++ files 2022-05-24 21:30:52 +02:00
fftools fftools/ffmpeg: call av_guess_frame_rate() when opening the file 2022-08-22 11:36:43 +02:00
libavcodec avcodec/pngdec: Fix APNG_DISPOSE_OP_BACKGROUND 2022-08-23 12:21:00 +02:00
libavdevice configure: always enable gnu_windres if available 2022-08-13 14:42:36 +02:00
libavfilter avfilter/af_alimiter: fix misbehavior when nb_channels != 2 2022-08-23 12:20:05 +02:00
libavformat lavf: deprecate av_stream_get_end_pts() 2022-08-22 11:35:43 +02:00
libavutil avutil/half2float: use native _Float16 if available 2022-08-19 22:09:36 +02:00
libpostproc configure: always enable gnu_windres if available 2022-08-13 14:42:36 +02:00
libswresample swresample/swresample: fill the correct buffer to print the output layout string 2022-08-21 17:46:36 -03:00
libswscale swscale/input: add rgbaf16 input support 2022-08-19 22:09:36 +02:00
presets
tests avutil/half2float: adjust conversion of NaN 2022-08-19 22:09:36 +02:00
tools tools: Make sure to create the tools directory before building decode_simple.o 2022-08-17 00:00:50 +03:00
.gitattributes
.gitignore gitignore: add config_components.h 2022-03-17 18:35:41 -03:00
.mailmap mailmap: add entry for myself 2021-03-09 02:09:55 +00:00
.travis.yml Merge commit '899ee03088d55152a48830df0899887f055da1de' 2019-03-14 15:53:16 -03:00
Changelog lavc/vaapi_encode: enable 8bit 4:4:4 encoding for HEVC and VP9 2022-08-09 09:22:49 -07:00
configure avutil/half2float: use native _Float16 if available 2022-08-19 22:09:36 +02:00
CONTRIBUTING.md
COPYING.GPLv2
COPYING.GPLv3
COPYING.LGPLv2.1
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INSTALL.md
LICENSE.md avfilter/vf_geq: Relicense to LGPL 2019-12-28 11:20:48 +01:00
MAINTAINERS MAINTAINERS: Add ED25519 key for signing my commits in the future 2022-08-09 21:57:31 +02:00
Makefile Makefile: Prompt for reconfigure on lavc/hwaccels.h modification 2022-07-01 00:34:38 +02:00
README.md README: fix typo and description of libavfilter 2021-10-08 09:44:34 +05:30
RELEASE RELEASE: update after 5.1 branch 2022-07-13 00:31:42 +02:00

README.md

FFmpeg README

FFmpeg is a collection of libraries and tools to process multimedia content such as audio, video, subtitles and related metadata.

Libraries

  • libavcodec provides implementation of a wider range of codecs.
  • libavformat implements streaming protocols, container formats and basic I/O access.
  • libavutil includes hashers, decompressors and miscellaneous utility functions.
  • libavfilter provides means to alter decoded audio and video through a directed graph of connected filters.
  • libavdevice provides an abstraction to access capture and playback devices.
  • libswresample implements audio mixing and resampling routines.
  • libswscale implements color conversion and scaling routines.

Tools

  • ffmpeg is a command line toolbox to manipulate, convert and stream multimedia content.
  • ffplay is a minimalistic multimedia player.
  • ffprobe is a simple analysis tool to inspect multimedia content.
  • Additional small tools such as aviocat, ismindex and qt-faststart.

Documentation

The offline documentation is available in the doc/ directory.

The online documentation is available in the main website and in the wiki.

Examples

Coding examples are available in the doc/examples directory.

License

FFmpeg codebase is mainly LGPL-licensed with optional components licensed under GPL. Please refer to the LICENSE file for detailed information.

Contributing

Patches should be submitted to the ffmpeg-devel mailing list using git format-patch or git send-email. Github pull requests should be avoided because they are not part of our review process and will be ignored.