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. Convert from YUV to formats for rendering/effects. Rotate by 90/180/270 degrees to adjust for mobile devices in portrait mode. Optimized for SSE2/SSSE3/AVX2 on x86/x64. Optimized for Neon on Arm. Optimized for DSP R2 on Mips.