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Now that we can directly promote these to plane swizzles, we generally want
to try pushing them in one direction - ideally towards the output, as in the
case of split subpasses, the output is guaranteed to be planar. (And there
may not even be a read)
Results in a lot of diffs, ranging from the benign, e.g.:
rgb24 -> bgr48be:
[ u8 XXXX -> +++X] SWS_OP_READ : 3 elem(s) packed >> 0
[ u8 ...X -> +++X] SWS_OP_CONVERT : u8 -> u16 (expand)
- [u16 ...X -> +++X] SWS_OP_SWIZZLE : 2103
[u16 ...X -> zzzX] SWS_OP_SWAP_BYTES
+ [u16 ...X -> zzzX] SWS_OP_SWIZZLE : 2103
[u16 ...X -> zzzX] SWS_OP_WRITE : 3 elem(s) packed >> 0
rgb24 -> gbrp9be:
[ u8 XXXX -> +++X] SWS_OP_READ : 3 elem(s) packed >> 0
[ u8 ...X -> +++X] SWS_OP_CONVERT : u8 -> f32
[f32 ...X -> ...X] SWS_OP_SCALE : * 511/255
[f32 ...X -> ...X] SWS_OP_DITHER : 16x16 matrix + {0 3 2 5}
[f32 ...X -> ...X] SWS_OP_MIN : x <= {511 511 511 _}
[f32 ...X -> +++X] SWS_OP_CONVERT : f32 -> u16
- [u16 ...X -> +++X] SWS_OP_SWIZZLE : 1203
[u16 ...X -> zzzX] SWS_OP_SWAP_BYTES
- [u16 ...X -> zzzX] SWS_OP_WRITE : 3 elem(s) planar >> 0
+ [u16 ...X -> zzzX] SWS_OP_WRITE : 3 elem(s) planar >> 0, via {2, 0, 1}
To the clear improvements, e.g.:
bgr24 -> gbrp16be:
[ u8 XXXX -> +++X] SWS_OP_READ : 3 elem(s) packed >> 0
- [ u8 ...X -> +++X] SWS_OP_SWIZZLE : 2103
[ u8 ...X -> +++X] SWS_OP_CONVERT : u8 -> u16 (expand)
- [u16 ...X -> +++X] SWS_OP_SWIZZLE : 1203
[u16 ...X -> zzzX] SWS_OP_SWAP_BYTES
- [u16 ...X -> zzzX] SWS_OP_WRITE : 3 elem(s) planar >> 0
+ [u16 ...X -> zzzX] SWS_OP_WRITE : 3 elem(s) planar >> 0, via {1, 0, 2}
The only case worth careful consideration is when there are swizzled inputs
that result in unusual plane patterns, e.g.:
argb -> gbrp9be:
[ u8 XXXX -> ++++] SWS_OP_READ : 4 elem(s) packed >> 0
- [ u8 X... -> ++++] SWS_OP_SWIZZLE : 1230
- [ u8 ...X -> ++++] SWS_OP_CONVERT : u8 -> f32
- [f32 ...X -> ....] SWS_OP_SCALE : * 511/255
- [f32 ...X -> ....] SWS_OP_DITHER : 16x16 matrix + {0 3 2 5}
- [f32 ...X -> ....] SWS_OP_MIN : x <= {511 511 511 _}
- [f32 ...X -> ++++] SWS_OP_CONVERT : f32 -> u16
- [u16 ...X -> ++++] SWS_OP_SWIZZLE : 1203
- [u16 ...X -> zzzz] SWS_OP_SWAP_BYTES
- [u16 ...X -> zzzz] SWS_OP_WRITE : 3 elem(s) planar >> 0
+ [ u8 X... -> ++++] SWS_OP_CONVERT : u8 -> f32
+ [f32 X... -> ....] SWS_OP_SCALE : * 511/255
+ [f32 X... -> ....] SWS_OP_DITHER : 16x16 matrix + {0 0 3 2}
+ [f32 X... -> ....] SWS_OP_MIN : x <= {511 511 511 511}
+ [f32 X... -> ++++] SWS_OP_CONVERT : f32 -> u16
+ [u16 X... -> zzzz] SWS_OP_SWAP_BYTES
+ [u16 X... -> zzzz] SWS_OP_SWIZZLE : 3120
+ [u16 ...X -> zzzz] SWS_OP_WRITE : 3 elem(s) planar >> 0, via {1, 2, 0}
(X = unused, z = byteswapped, + = exact, 0 = zero)
Observe the change from ...X to X..., which is a pattern that doesn't
necessarily have a fast path and would usually end up falling back to the
generic 4-component implementations (rather than the 3-component ones).
That said, this is not a big deal, since we can ultimately re-align the
set of implementations with what's actually needed; once we're done with
plane splitting and so forth.
Sponsored-by: Sovereign Tech Fund
Signed-off-by: Niklas Haas <git@haasn.dev>
FFmpeg README
FFmpeg is a collection of libraries and tools to process multimedia content such as audio, video, subtitles and related metadata.
Libraries
libavcodecprovides implementation of a wider range of codecs.libavformatimplements streaming protocols, container formats and basic I/O access.libavutilincludes hashers, decompressors and miscellaneous utility functions.libavfilterprovides means to alter decoded audio and video through a directed graph of connected filters.libavdeviceprovides an abstraction to access capture and playback devices.libswresampleimplements audio mixing and resampling routines.libswscaleimplements 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,ismindexandqt-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.