For test purposes, environment variables can be set to control libyuv behavior. These should only be used for testing, to narrow down bugs or to test performance.

CPU

By default the cpu is detected and the most advanced form of SIMD is used. But you can disable instruction sets selectively, or completely, falling back on C code. Set the variable to 1 to disable the specified instruction set.

LIBYUV_DISABLE_ASM
LIBYUV_DISABLE_X86
LIBYUV_DISABLE_SSE2
LIBYUV_DISABLE_SSSE3
LIBYUV_DISABLE_SSE41
LIBYUV_DISABLE_SSE42
LIBYUV_DISABLE_AVX
LIBYUV_DISABLE_AVX2
LIBYUV_DISABLE_AVX3
LIBYUV_DISABLE_ERMS
LIBYUV_DISABLE_FMA3
LIBYUV_DISABLE_DSPR2
LIBYUV_DISABLE_NEON

Test Width/Height/Repeat

The unittests default to a small image (128x72) to run fast. This can be set by environment variable to test a specific resolutions. You can also repeat the test a specified number of iterations, allowing benchmarking and profiling.

set LIBYUV_WIDTH=1280
set LIBYUV_HEIGHT=720
set LIBYUV_REPEAT=999
set LIBYUV_FLAGS=-1
set LIBYUV_CPU_INFO=-1