diff options
Diffstat (limited to 'media')
| -rw-r--r-- | media/base/yuv_convert.cc | 115 |
1 files changed, 29 insertions, 86 deletions
diff --git a/media/base/yuv_convert.cc b/media/base/yuv_convert.cc index 72f89a1..7e4da5e 100644 --- a/media/base/yuv_convert.cc +++ b/media/base/yuv_convert.cc @@ -6,92 +6,34 @@ // http://www.fourcc.org/yuv.php // The actual conversion is best described here // http://en.wikipedia.org/wiki/YUV -// excerpt from wiki: -// These formulae are based on the NTSC standard; -// Y' = 0.299 x R + 0.587 x G + 0.114 x B -// U = -0.147 x R - 0.289 x G + 0.436 x B -// V = 0.615 x R - 0.515 x G - 0.100 x B -// On older, non-SIMD architectures, floating point arithmetic is much -// slower than using fixed-point arithmetic, so an alternative formulation -// is: -// c = Y' - 16 -// d = U - 128 -// e = V - 128 -// Using the previous coefficients and noting that clip() denotes clipping a -// value to the range of 0 to 255, the following formulae provide the -// conversion from Y'UV to RGB (NTSC version): -// R = clip((298 x c + 409 x e + 128) >> 8) -// G = clip((298 x c - 100 x d - 208 x e + 128) >> 8) -// B = clip((298 x c + 516 x d + 128) >> 8) -// // An article on optimizing YUV conversion using tables instead of multiplies -// http://lestourtereaux.free.fr/papers/data/yuvrgb.pdf +// http://lestourtereaux.free.fr/papers/data/yuvrgb.pdf // // YV12 is a full plane of Y and a half height, half width chroma planes // YV16 is a full plane of Y and a full height, half width chroma planes // -// Implimentation notes -// This version uses MMX for Visual C and GCC, which should cover all -// current platforms. C++ is included for reference and future platforms. -// -// ARGB pixel format is output, which on little endian is stored as BGRA. -// The alpha is filled in, allowing the application to use RGBA or RGB32. -// -// The Visual C assembler is considered the source. -// The GCC asm was created by compiling with Visual C and disassembling -// with GNU objdump. -// cl /c /Ox yuv_convert.cc -// objdump -d yuv_convert.o -// The code almost copy/pasted in, except the table lookups, which produced -// movq 0x800(,%eax,8),%mm0 -// and needed to be changed to cdecl style table names -// "movq _coefficients_RGB_U(,%eax,8),%mm0\n" -// extern "C" was used to avoid name mangling. -// -// Once compiled with both MinGW GCC and Visual C on PC, performance should -// be identical. A small difference will occur in the C++ calling code, -// depending on the frame size. -// To confirm the same code is being generated -// g++ -O3 -c yuv_convert.cc -// dumpbin -disasm yuv_convert.o >gcc.txt -// cl /Ox /c yuv_convert.cc -// dumpbin -disasm yuv_convert.obj >vc.txt -// and compare the files. -// -// The GCC function label is inside the assembler to avoid a stack frame -// push ebp, that may vary depending on compile options. +// ARGB pixel format is output, which on little endian is stored as BGRA. +// The alpha is set to 255, allowing the application to use RGBA or RGB32. #include "media/base/yuv_convert.h" -#ifdef _OPENMP -#include <omp.h> -#endif - -#ifdef _DEBUG -#include "base/logging.h" -#else -#define DCHECK(a) -#endif - // Header for low level row functions. #include "media/base/yuv_row.h" namespace media { + // Convert a frame of YUV to 32 bit ARGB. void ConvertYUVToRGB32(const uint8* y_buf, - const uint8* u_buf, - const uint8* v_buf, - uint8* rgb_buf, - int width, - int height, - int y_pitch, - int uv_pitch, - int rgb_pitch, - YUVType yuv_type) { + const uint8* u_buf, + const uint8* v_buf, + uint8* rgb_buf, + int width, + int height, + int y_pitch, + int uv_pitch, + int rgb_pitch, + YUVType yuv_type) { unsigned int y_shift = yuv_type; -#ifdef _OPENMP -#pragma omp parallel for -#endif for (int y = 0; y < height; ++y) { uint8* rgb_row = rgb_buf + y * rgb_pitch; const uint8* y_ptr = y_buf + y * y_pitch; @@ -104,23 +46,25 @@ void ConvertYUVToRGB32(const uint8* y_buf, rgb_row, width); } + + // MMX used for FastConvertYUVToRGB32Row requires emms instruction. EMMS(); } // Scale a frame of YUV to 32 bit ARGB. void ScaleYUVToRGB32(const uint8* y_buf, - const uint8* u_buf, - const uint8* v_buf, - uint8* rgb_buf, - int width, - int height, - int scaled_width, - int scaled_height, - int y_pitch, - int uv_pitch, - int rgb_pitch, - YUVType yuv_type, - Rotate view_rotate) { + const uint8* u_buf, + const uint8* v_buf, + uint8* rgb_buf, + int width, + int height, + int scaled_width, + int scaled_height, + int y_pitch, + int uv_pitch, + int rgb_pitch, + YUVType yuv_type, + Rotate view_rotate) { unsigned int y_shift = yuv_type; // Diagram showing origin and direction of source sampling. // ->0 4<- @@ -180,9 +124,6 @@ void ScaleYUVToRGB32(const uint8* y_buf, } } -#ifdef _OPENMP -#pragma omp parallel for -#endif for (int y = 0; y < scaled_height; ++y) { uint8* dest_pixel = rgb_buf + y * rgb_pitch; int scaled_y = (y * height / scaled_height); @@ -218,6 +159,8 @@ void ScaleYUVToRGB32(const uint8* y_buf, dest_pixel, scaled_width, scaled_dx); } } + + // MMX used for FastConvertYUVToRGB32Row requires emms instruction. EMMS(); } |