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Andriy Gelman e3b49aaa4e avcodec/v4l2_context: Drop empty packet while draining
v4l2_m2m devices may send an empty packet/frame while draining
to indicate that all capture buffers have been flushed.

Currently, the empty packet/frame is not handled correctly:
When encoding, the empty packet is forwarded to the muxer, usually
creating warnings.
When decoding, a reference to the memory is created anyway. Since in
the past this memory contained a decoded frame, it results in an extra
frame being decoded.

This commit discards the empty packet/frame.

References:
linux/Documentation/media/uapi/v4l/dev-decoder.rst:

    "The last buffer may be empty (with :c:type:`v4l2_buffer` bytesused = 0)
     and in that case it must be ignored by the client, as it does not
     contain a decoded frame."

linux/Documentation/media/uapi/media/v4l/vidioc-encoder-cmd.rst:

    "...This buffer may be empty, indicated by the
     driver setting the ``bytesused`` field to 0."

Reviewed-by: Ming Qian <ming.qian@nxp.com>
Signed-off-by: Andriy Gelman <andriy.gelman@gmail.com>
2020-05-09 19:34:41 -04:00
2017-01-27 17:06:42 +01:00
2020-03-31 04:14:14 -05:00
2016-09-18 10:02:13 +01:00
2019-01-31 10:29:16 -09:00
2019-12-28 11:20:48 +01:00
2018-01-06 18:31:37 +00:00

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 a mean to alter decoded Audio and Video through chain of 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.

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