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| -rw-r--r-- | third_party/aom/doc/dev_guide/av1_encoder.dox | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/third_party/aom/doc/dev_guide/av1_encoder.dox b/third_party/aom/doc/dev_guide/av1_encoder.dox index 0f7e8f87e2..a40b58933b 100644 --- a/third_party/aom/doc/dev_guide/av1_encoder.dox +++ b/third_party/aom/doc/dev_guide/av1_encoder.dox @@ -1313,6 +1313,34 @@ Related functions: All the related functions are listed in \ref coefficient_coding. +\section architecture_simd SIMD usage + +In order to efficiently encode video on modern platforms, it is necessary to +implement optimized versions of many core encoding and decoding functions using +architecture-specific SIMD instructions. + +Functions which have optimized implementations will have multiple variants +in the code, each suffixed with the name of the appropriate instruction set. +There will additionally be an `_c` version, which acts as a reference +implementation which the SIMD variants can be tested against. + +As different machines with the same nominal architecture may support different +subsets of SIMD instructions, we have dynamic CPU detection logic which chooses +the appropriate functions to use at run time. This process is handled by +`build/cmake/rtcd.pl`, with function definitions in the files +`*_rtcd_defs.pl` elsewhere in the codebase. + +Currently SIMD is supported on the following platforms: + +- x86: Requires SSE4.1 or above + +- Arm: Requires Neon (Armv7-A and above) + +We aim to provide implementations of all performance-critical functions which +are compatible with the instruction sets listed above. Additional SIMD +extensions (e.g. AVX on x86, SVE on Arm) are also used to provide even +greater performance where available. + */ /*!\defgroup encoder_algo Encoder Algorithm |