[FFmpeg-devel] [PATCH] vf_framestep: add blend parameter for motion blur effect

[Matthias C. M. Troffaes]

Attached a patch which adds a "blend" parameter to the framestep
filter, to blend frames together at each step, for a motion blur
effect. The number of frames that are blended (i.e. the exposure time,
in frames) can be controlled, allowing control over the strength of
the motion blur. The filter has timeline support, and supports both
8-bit and 16-bit pixel formats. Tests and documentation included.

Note that a similar effect is already possible by repeatedly chaining
the tblend and framestep=step=2 filters; see for example:

https://video.stackexchange.com/questions/16552/4x-resample-videoframes-using-ffmpeg

But this is limited to steps that are powers of two, and this does not
allow an intermediate exposure time. It's also slower.

The main use I've had for the attached patch myself is to blend down
rendered high framerate footage to get a high quality motion blur
effect.

Matthias C. M. Troffaes (1):
  vf_framestep: add blend parameter for motion blur effect

 Changelog                         |   1 +
 doc/filters.texi                  |   7 ++
 libavfilter/vf_framestep.c        | 242 ++++++++++++++++++++++++++++++++++----
 tests/fate/filter-video.mak       |   5 +
 tests/ref/fate/filter-framestep-1 |  17 +++
 tests/ref/fate/filter-framestep-2 |  17 +++
 tests/ref/fate/filter-framestep-3 |  17 +++
 7 files changed, 286 insertions(+), 20 deletions(-)
 create mode 100644 tests/ref/fate/filter-framestep-1
 create mode 100644 tests/ref/fate/filter-framestep-2
 create mode 100644 tests/ref/fate/filter-framestep-3

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2.7.4