FFmpeg

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Tag: Branch: Tree: ccb81acc3d

Commit Graph

Author	SHA1	Message	Date
Niklas Haas	6bc29a6b57	avcodec/h274: add film grain synthesis routine This could arguably also be a vf, but I decided to put it here since decoders are technically required to apply film grain during the output step, and I would rather want to avoid requiring users insert the correct film grain synthesis filter on their own. The code, while in C, is written in a way that unrolls/vectorizes fairly well under -O3, and is reasonably cache friendly. On my CPU, a single thread pushes about 400 FPS at 1080p. Apart from hand-written assembly, one possible avenue of improvement would be to change the access order to compute the grain row-by-row rather than in 8x8 blocks. This requires some redundant PRNG calls, but would make the algorithm more cache-oblivious. The implementation has been written to the wording of SMPTE RDD 5-2006 as faithfully as I can manage. However, apart from passing a visual inspection, no guarantee of correctness can be made due to the lack of any publicly available reference implementation against which to compare it. Signed-off-by: Niklas Haas <git@haasn.dev> Signed-off-by: James Almer <jamrial@gmail.com>	4 years ago

Author

SHA1

Message

Date

Niklas Haas

6bc29a6b57

avcodec/h274: add film grain synthesis routine

This could arguably also be a vf, but I decided to put it here since
decoders are technically required to apply film grain during the output
step, and I would rather want to avoid requiring users insert the
correct film grain synthesis filter on their own.

The code, while in C, is written in a way that unrolls/vectorizes fairly
well under -O3, and is reasonably cache friendly. On my CPU, a single
thread pushes about 400 FPS at 1080p.

Apart from hand-written assembly, one possible avenue of improvement
would be to change the access order to compute the grain row-by-row
rather than in 8x8 blocks. This requires some redundant PRNG calls, but
would make the algorithm more cache-oblivious.

The implementation has been written to the wording of SMPTE RDD 5-2006
as faithfully as I can manage. However, apart from passing a visual
inspection, no guarantee of correctness can be made due to the lack of
any publicly available reference implementation against which to
compare it.

Signed-off-by: Niklas Haas <git@haasn.dev>
Signed-off-by: James Almer <jamrial@gmail.com>

4 years ago

1 Commits (ccb81acc3d1beb2235ff29bbc05e60db41de9039)