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The existing code performs a lot of shifts and combines the R and B
components into a single vector unnecessarily. We can express this much
more cleanly by making use of the SRI instruction to insert and replace
shifted bits into the original data, performing the 5/6-bit to 8-bit
expansion in a single instruction if the source bits are already in the
high bits of the byte. We still need a single separate XTN instruction
to narrow the B component before the left shift since Neon does not have
a narrowing left shift instruction.
Reduction in runtime for selected kernels:
Kernel | Cortex-A55 | Cortex-A76 | Cortex-X2
RGB565ToYRow_NEON | -22.1% | -23.4% | -25.1%
RGB565ToUVRow_NEON | -26.8% | -20.5% | -18.8%
RGB565ToARGBRow_NEON | -38.9% | -32.0% | -23.5%
Bug: libyuv:976
Change-Id: I77b8d58287b70dbb9549451fc15ed3dd0d2a4dda
Reviewed-on: https://chromium-review.googlesource.com/c/libyuv/libyuv/+/5374286
Reviewed-by: Frank Barchard <fbarchard@chromium.org>
Reviewed-by: Justin Green <greenjustin@google.com>
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| build_overrides | ||
| docs | ||
| include | ||
| infra/config | ||
| riscv_script | ||
| source | ||
| tools_libyuv | ||
| unit_test | ||
| util | ||
| .clang-format | ||
| .gitignore | ||
| .gn | ||
| .vpython | ||
| .vpython3 | ||
| Android.bp | ||
| Android.mk | ||
| AUTHORS | ||
| BUILD.gn | ||
| CM_linux_packages.cmake | ||
| CMakeLists.txt | ||
| codereview.settings | ||
| DEPS | ||
| DIR_METADATA | ||
| download_vs_toolchain.py | ||
| libyuv.gni | ||
| libyuv.gyp | ||
| libyuv.gypi | ||
| LICENSE | ||
| linux.mk | ||
| OWNERS | ||
| PATENTS | ||
| PRESUBMIT.py | ||
| public.mk | ||
| pylintrc | ||
| README.chromium | ||
| README.md | ||
| winarm.mk | ||
libyuv is an open source project that includes YUV scaling and conversion functionality.
- Scale YUV to prepare content for compression, with point, bilinear or box filter.
- Convert to YUV from webcam formats for compression.
- Convert to RGB formats for rendering/effects.
- Rotate by 90/180/270 degrees to adjust for mobile devices in portrait mode.
- Optimized for SSSE3/AVX2 on x86/x64.
- Optimized for Neon on Arm.
- Optimized for MSA on Mips.
- Optimized for RVV on RISC-V.
Development
See Getting started for instructions on how to get started developing.
You can also browse the docs directory for more documentation.