diff options
Diffstat (limited to 'media/base/yuv_convert.cc')
| -rw-r--r-- | media/base/yuv_convert.cc | 59 |
1 files changed, 30 insertions, 29 deletions
diff --git a/media/base/yuv_convert.cc b/media/base/yuv_convert.cc index 1c5ff785d..dd40c9f 100644 --- a/media/base/yuv_convert.cc +++ b/media/base/yuv_convert.cc @@ -14,15 +14,15 @@ // 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 +// 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) +// 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 @@ -339,14 +339,14 @@ void ConvertYV12ToRGB32Row(const uint8* y_buf, shr ecx, 1 wloop : - movzx eax, byte ptr [edi] + movzx eax, byte ptr [edi] // NOLINT add edi, 1 - movzx ebx, byte ptr [esi] + movzx ebx, byte ptr [esi] // NOLINT add esi, 1 movq mm0, [coefficients_RGB_U + 8 * eax] - movzx eax, byte ptr [edx] + movzx eax, byte ptr [edx] // NOLINT paddsw mm0, [coefficients_RGB_V + 8 * ebx] - movzx ebx, byte ptr [edx + 1] + movzx ebx, byte ptr [edx + 1] // NOLINT movq mm1, [coefficients_RGB_Y + 8 * eax] add edx, 2 movq mm2, [coefficients_RGB_Y + 8 * ebx] @@ -556,7 +556,7 @@ static uint8 g_rgb_clip_table[kClipOverflow + kClipTableSize + kClipOverflow] = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // 128 underflow values - 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // clamped to 0. + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // cliped to 0. 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, @@ -604,7 +604,7 @@ static uint8 g_rgb_clip_table[kClipOverflow 0xF0, 0xF1, 0xF2, 0xF3, 0xF4, 0xF5, 0xF6, 0xF7, 0xF8, 0xF9, 0xFA, 0xFB, 0xFC, 0xFD, 0xFE, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 128 overflow values - 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // clamped to 255. + 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // cliped to 255. 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, @@ -625,14 +625,15 @@ static uint8 g_rgb_clip_table[kClipOverflow // Source is signed fixed point 8.8. // Table allows for values to underflow or overflow by 128. // Therefore source range is -128 to 384. -// Output clamps to unsigned 0 to 255. +// Output clips to unsigned 0 to 255. static inline uint32 clip(int32 value) { - DCHECK((((value) >> 8) + kClipOverflow) >= 0); - DCHECK((((value) >> 8) + kClipOverflow) - < kClipOverflow + kClipTableSize + kClipOverflow); + DCHECK(((value >> 8) + kClipOverflow) >= 0); + DCHECK(((value >> 8) + kClipOverflow) < + (kClipOverflow + kClipTableSize + kClipOverflow)); return static_cast<uint32>(g_rgb_clip_table[((value) >> 8) + kClipOverflow]); } + void ConvertYV12ToRGB32Row(const uint8* y_buf, const uint8* u_buf, const uint8* v_buf, @@ -641,26 +642,26 @@ void ConvertYV12ToRGB32Row(const uint8* y_buf, for (int32 x = 0; x < static_cast<int32>(width); x += 2) { uint8 u = u_buf[x >> 1]; uint8 v = v_buf[x >> 1]; - int32 D = static_cast<int32>(u) - 128; - int32 E = static_cast<int32>(v) - 128; + int32 d = static_cast<int32>(u) - 128; + int32 e = static_cast<int32>(v) - 128; - int32 Cb = (516 * D + 128); - int32 Cg = (- 100 * D - 208 * E + 128); - int32 Cr = (409 * E + 128); + int32 cb = (516 * d + 128); + int32 cg = (- 100 * d - 208 * e + 128); + int32 cr = (409 * e + 128); uint8 y0 = y_buf[x]; int32 C298a = ((static_cast<int32>(y0) - 16) * 298 + 128); - *reinterpret_cast<uint32*>(rgb_buf) = clip(C298a + Cb) - | (clip(C298a + Cg) << 8) - | (clip(C298a + Cr) << 16) - | 0xff000000; + *reinterpret_cast<uint32*>(rgb_buf) = clip(C298a + cb) | + (clip(C298a + cg) << 8) | + (clip(C298a + cr) << 16) | + 0xff000000; uint8 y1 = y_buf[x + 1]; int32 C298b = ((static_cast<int32>(y1) - 16) * 298 + 128); - *reinterpret_cast<uint32*>(rgb_buf + 4) = clip(C298b + Cb) - | (clip(C298b + Cg) << 8) - | (clip(C298b + Cr) << 16) - | 0xff000000; + *reinterpret_cast<uint32*>(rgb_buf + 4) = clip(C298b + cb) | + (clip(C298b + cg) << 8) | + (clip(C298b + cr) << 16) | + 0xff000000; rgb_buf += 8; // Advance 2 pixels. } |