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10% faster table-less SSE2/NEON version of YUV->RGB conversion

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* Precision is slightly different
* also implemented in SSE2 the missing WebPUpsamplers for MODE_ARGB, MODE_Argb, MODE_RGB565, etc.
* removing yuv_tables_sse2.h saved ~8k of binary size
* the mips32/mips_dsp_r2 code is disabled for now, since it has drifted away
* the NEON code is somewhat tricky

Change-Id: Icf205faa62cf46c2825d79f3af6725dc1ec7f052
This commit is contained in:
Pascal Massimino
2015-12-08 12:31:47 +01:00
committed by James Zern
parent bd91af200a
commit ac761a3738
11 changed files with 286 additions and 887 deletions
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123
src/dsp/yuv.h
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@ -21,16 +21,15 @@
// G = 1.164 * (Y-16) - 0.813 * (V-128) - 0.391 * (U-128)
// B = 1.164 * (Y-16) + 2.018 * (U-128)
// where Y is in the [16,235] range, and U/V in the [16,240] range.
// In the table-lookup version (WEBP_YUV_USE_TABLE), the common factor
// "1.164 * (Y-16)" can be handled as an offset in the VP8kClip[] table.
// So in this case the formulae should read:
// R = 1.164 * [Y + 1.371 * (V-128) ] - 18.624
// G = 1.164 * [Y - 0.698 * (V-128) - 0.336 * (U-128)] - 18.624
// B = 1.164 * [Y + 1.733 * (U-128)] - 18.624
// once factorized.
// For YUV->RGB conversion, only 14bit fixed precision is used (YUV_FIX2).
// That's the maximum possible for a convenient ARM implementation.
//
// The fixed-point implementation used here is:
// R = (19077 . y + 26149 . v - 14234) >> 6
// G = (19077 . y - 6419 . u - 13320 . v + 8708) >> 6
// B = (19077 . y + 33050 . u - 17685) >> 6
// where the '.' operator is the mulhi_epu16 variant:
// a . b = ((a << 8) * b) >> 16
// that preserves 8 bits of fractional precision before final descaling.
// Author: Skal (pascal.massimino@gmail.com)
#ifndef WEBP_DSP_YUV_H_
@ -39,9 +38,6 @@
#include "./dsp.h"
#include "../dec/decode_vp8.h"
// Define the following to use the LUT-based code:
// #define WEBP_YUV_USE_TABLE
#if defined(WEBP_EXPERIMENTAL_FEATURES)
// Do NOT activate this feature for real compression. This is only experimental!
// This flag is for comparison purpose against JPEG's "YUVj" natural colorspace.
@ -66,41 +62,32 @@ enum {
YUV_RANGE_MIN = -227, // min value of r/g/b output
YUV_RANGE_MAX = 256 + 226, // max value of r/g/b output
YUV_FIX2 = 14, // fixed-point precision for YUV->RGB
YUV_HALF2 = 1 << (YUV_FIX2 - 1),
YUV_FIX2 = 6, // fixed-point precision for YUV->RGB
YUV_HALF2 = 1 << YUV_FIX2 >> 1,
YUV_MASK2 = (256 << YUV_FIX2) - 1
};
// These constants are 14b fixed-point version of ITU-R BT.601 constants.
#define kYScale 19077 // 1.164 = 255 / 219
#define kVToR 26149 // 1.596 = 255 / 112 * 0.701
#define kUToG 6419 // 0.391 = 255 / 112 * 0.886 * 0.114 / 0.587
#define kVToG 13320 // 0.813 = 255 / 112 * 0.701 * 0.299 / 0.587
#define kUToB 33050 // 2.018 = 255 / 112 * 0.886
#define kRCst (-kYScale * 16 - kVToR * 128 + YUV_HALF2)
#define kGCst (-kYScale * 16 + kUToG * 128 + kVToG * 128 + YUV_HALF2)
#define kBCst (-kYScale * 16 - kUToB * 128 + YUV_HALF2)
//------------------------------------------------------------------------------
// slower on x86 by ~7-8%, but bit-exact with the SSE2/NEON version
#if !defined(WEBP_YUV_USE_TABLE)
// slower on x86 by ~7-8%, but bit-exact with the SSE2 version
static WEBP_INLINE int MultHi(int v, int coeff) { // _mm_mulhi_epu16 emulation
return (v * coeff) >> 8;
}
static WEBP_INLINE int VP8Clip8(int v) {
return ((v & ~YUV_MASK2) == 0) ? (v >> YUV_FIX2) : (v < 0) ? 0 : 255;
}
static WEBP_INLINE int VP8YUVToR(int y, int v) {
return VP8Clip8(kYScale * y + kVToR * v + kRCst);
return VP8Clip8(MultHi(y, 19077) + MultHi(v, 26149) - 14234);
}
static WEBP_INLINE int VP8YUVToG(int y, int u, int v) {
return VP8Clip8(kYScale * y - kUToG * u - kVToG * v + kGCst);
return VP8Clip8(MultHi(y, 19077) - MultHi(u, 6419) - MultHi(v, 13320) + 8708);
}
static WEBP_INLINE int VP8YUVToB(int y, int u) {
return VP8Clip8(kYScale * y + kUToB * u + kBCst);
return VP8Clip8(MultHi(y, 19077) + MultHi(u, 33050) - 17685);
}
static WEBP_INLINE void VP8YuvToRgb(int y, int u, int v,
@ -149,73 +136,6 @@ static WEBP_INLINE void VP8YuvToRgba4444(int y, int u, int v,
#endif
}
#else
// Table-based version, not totally equivalent to the SSE2 version.
// Rounding diff is only +/-1 though.
extern int16_t VP8kVToR[256], VP8kUToB[256];
extern int32_t VP8kVToG[256], VP8kUToG[256];
extern uint8_t VP8kClip[YUV_RANGE_MAX - YUV_RANGE_MIN];
extern uint8_t VP8kClip4Bits[YUV_RANGE_MAX - YUV_RANGE_MIN];
static WEBP_INLINE void VP8YuvToRgb(int y, int u, int v,
uint8_t* const rgb) {
const int r_off = VP8kVToR[v];
const int g_off = (VP8kVToG[v] + VP8kUToG[u]) >> YUV_FIX;
const int b_off = VP8kUToB[u];
rgb[0] = VP8kClip[y + r_off - YUV_RANGE_MIN];
rgb[1] = VP8kClip[y + g_off - YUV_RANGE_MIN];
rgb[2] = VP8kClip[y + b_off - YUV_RANGE_MIN];
}
static WEBP_INLINE void VP8YuvToBgr(int y, int u, int v,
uint8_t* const bgr) {
const int r_off = VP8kVToR[v];
const int g_off = (VP8kVToG[v] + VP8kUToG[u]) >> YUV_FIX;
const int b_off = VP8kUToB[u];
bgr[0] = VP8kClip[y + b_off - YUV_RANGE_MIN];
bgr[1] = VP8kClip[y + g_off - YUV_RANGE_MIN];
bgr[2] = VP8kClip[y + r_off - YUV_RANGE_MIN];
}
static WEBP_INLINE void VP8YuvToRgb565(int y, int u, int v,
uint8_t* const rgb) {
const int r_off = VP8kVToR[v];
const int g_off = (VP8kVToG[v] + VP8kUToG[u]) >> YUV_FIX;
const int b_off = VP8kUToB[u];
const int rg = ((VP8kClip[y + r_off - YUV_RANGE_MIN] & 0xf8) |
(VP8kClip[y + g_off - YUV_RANGE_MIN] >> 5));
const int gb = (((VP8kClip[y + g_off - YUV_RANGE_MIN] << 3) & 0xe0) |
(VP8kClip[y + b_off - YUV_RANGE_MIN] >> 3));
#ifdef WEBP_SWAP_16BIT_CSP
rgb[0] = gb;
rgb[1] = rg;
#else
rgb[0] = rg;
rgb[1] = gb;
#endif
}
static WEBP_INLINE void VP8YuvToRgba4444(int y, int u, int v,
uint8_t* const argb) {
const int r_off = VP8kVToR[v];
const int g_off = (VP8kVToG[v] + VP8kUToG[u]) >> YUV_FIX;
const int b_off = VP8kUToB[u];
const int rg = ((VP8kClip4Bits[y + r_off - YUV_RANGE_MIN] << 4) |
VP8kClip4Bits[y + g_off - YUV_RANGE_MIN]);
const int ba = (VP8kClip4Bits[y + b_off - YUV_RANGE_MIN] << 4) | 0x0f;
#ifdef WEBP_SWAP_16BIT_CSP
argb[0] = ba;
argb[1] = rg;
#else
argb[0] = rg;
argb[1] = ba;
#endif
}
#endif // WEBP_YUV_USE_TABLE
//-----------------------------------------------------------------------------
// Alpha handling variants
@ -245,11 +165,7 @@ void VP8YUVInit(void);
#if defined(WEBP_USE_SSE2)
// When the following is defined, tables are initialized statically, adding ~12k
// to the binary size. Otherwise, they are initialized at run-time (small cost).
#define WEBP_YUV_USE_SSE2_TABLES
// Process 32 pixels and store the result (24b or 32b per pixel) in *dst.
// Process 32 pixels and store the result (16b, 24b or 32b per pixel) in *dst.
void VP8YuvToRgba32(const uint8_t* y, const uint8_t* u, const uint8_t* v,
uint8_t* dst);
void VP8YuvToRgb32(const uint8_t* y, const uint8_t* u, const uint8_t* v,
@ -259,9 +175,6 @@ void VP8YuvToBgra32(const uint8_t* y, const uint8_t* u, const uint8_t* v,
void VP8YuvToBgr32(const uint8_t* y, const uint8_t* u, const uint8_t* v,
uint8_t* dst);
// Must be called to initialize tables before using the functions.
void VP8YUVInitSSE2(void);
#endif // WEBP_USE_SSE2
//------------------------------------------------------------------------------