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Rather than shifting the data into the low half of each lane and then
using a saturating narrowing operation, we can do the saturation as part
of a shift into the highest half of the lane and then use a simpler TRN2
instruction to extract pairs of high halves into full vectors. This also
has the nice advantage of allowing us to use ST2 rather than ST4 for
storing the result, since ST4 is known to be slow on some
micro-architectures.
Reduction in runtimes observed for the two kernels:
| MergeARGB16To8Row_NEON | MergeXRGB16To8Row_NEON
Cortex-A55 | -8.0% | -12.2%
Cortex-A510 | -29.9% | -31.4%
Cortex-A76 | -29.0% | -32.0%
Cortex-X2 | -33.5% | -43.4%
Bug: libyuv:976
Change-Id: I9da3beedc27ab43527b3642aa6d4decf3b5b6683
Reviewed-on: https://chromium-review.googlesource.com/c/libyuv/libyuv/+/5509198
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.