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WIP: extract the float-calculation of HuffmanCost from loop

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new function: VP8FinalHuffmanCost()

Change-Id: I42102f8e5ef6d7a7af66490af77b7dc2048a9cb9
This commit is contained in:
skal 2014-04-14 17:57:26 +02:00
parent 8ff96a027a
commit b30a04cf11
2 changed files with 39 additions and 27 deletions
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59
src/enc/histogram.c
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@ -188,59 +188,64 @@ static WEBP_INLINE double InitialHuffmanCost(void) {
return kHuffmanCodeOfHuffmanCodeSize - kSmallBias; return kHuffmanCodeOfHuffmanCodeSize - kSmallBias;
} }
static WEBP_INLINE double HuffmanCostRefine(int streak, int val) { double VP8FinalHuffmanCost(int cnt_z, int streak_z_le3, int streak_z_gt3,
double retval; int cnt_nz, int streak_nz_le3, int streak_nz_gt3) {
if (streak > 3) { double retval = InitialHuffmanCost();
if (val == 0) { retval += cnt_z * 1.5625 + 0.234375 * streak_z_gt3;
retval = 1.5625 + 0.234375 * streak; retval += cnt_nz * 2.578125 + 0.703125 * streak_nz_gt3;
} else { retval += 1.796875 * streak_z_le3;
retval = 2.578125 + 0.703125 * streak; retval += 3.28125 * streak_nz_le3;
}
} else {
if (val == 0) {
retval = 1.796875 * streak;
} else {
retval = 3.28125 * streak;
}
}
return retval; return retval;
} }
// Returns the cost encode the rle-encoded entropy code. // Returns the cost encode the rle-encoded entropy code.
// The constants in this function are experimental. // The constants in this function are experimental.
static double HuffmanCost(const int* const population, int length) { static double HuffmanCost(const int* const population, int length) {
int cnts[2] = { 0, 0 };
int streaks[2][2] = { { 0, 0 }, { 0, 0 } };
int streak = 0; int streak = 0;
int i = 0; int i;
double retval = InitialHuffmanCost(); for (i = 0; i < length - 1; ++i) {
for (; i < length - 1; ++i) {
++streak; ++streak;
if (population[i] == population[i + 1]) { if (population[i] == population[i + 1]) {
continue; continue;
} }
retval += HuffmanCostRefine(streak, population[i]); cnts[population[i] != 0] += (streak > 3);
streaks[population[i] != 0][(streak > 3)] += streak;
streak = 0; streak = 0;
} }
retval += HuffmanCostRefine(++streak, population[i]); ++streak;
return retval; cnts[population[i] != 0] += (streak > 3);
streaks[population[i] != 0][(streak > 3)] += streak;
return VP8FinalHuffmanCost(cnts[0], streaks[0][0], streaks[0][1],
cnts[1], streaks[1][0], streaks[1][1]);
} }
static double HuffmanCostCombined(const int* const X, const int* const Y, static double HuffmanCostCombined(const int* const X, const int* const Y,
int length) { int length) {
int cnts[2] = { 0, 0 };
int streaks[2][2] = { { 0, 0 }, { 0, 0 } };
int streak = 0; int streak = 0;
int i = 0; int i;
double retval = InitialHuffmanCost(); for (i = 0; i < length - 1; ++i) {
for (; i < length - 1; ++i) {
const int xy = X[i] + Y[i]; const int xy = X[i] + Y[i];
const int xy_next = X[i + 1] + Y[i + 1]; const int xy_next = X[i + 1] + Y[i + 1];
++streak; ++streak;
if (xy == xy_next) { if (xy == xy_next) {
continue; continue;
} }
retval += HuffmanCostRefine(streak, xy); cnts[xy != 0] += (streak > 3);
streaks[xy != 0][streak > 3] += streak;
streak = 0; streak = 0;
} }
retval += HuffmanCostRefine(++streak, X[i] + Y[i]); {
return retval; const int xy = X[i] + Y[i];
++streak;
cnts[xy != 0] += (streak > 3);
streaks[xy != 0][streak > 3] += streak;
}
return VP8FinalHuffmanCost(cnts[0], streaks[0][0], streaks[0][1],
cnts[1], streaks[1][0], streaks[1][1]);
} }
static double PopulationCost(const int* const population, int length) { static double PopulationCost(const int* const population, int length) {

7
src/enc/histogram.h
View File

@ -90,6 +90,13 @@ static WEBP_INLINE int VP8LHistogramNumCodes(int palette_code_bits) {
((palette_code_bits > 0) ? (1 << palette_code_bits) : 0); ((palette_code_bits > 0) ? (1 << palette_code_bits) : 0);
} }
// Used to finalized the Huffman cost:
// cnt_z / cnt_nz: counts the number of 0's and non-0's
// streak_{z,nz}_le3 / streak_{z,nz}_gt3: number of streaks larger than 3
// or less-or-equal than 3.
double VP8FinalHuffmanCost(int cnt_z, int streak_z_le3, int streak_z_gt3,
int cnt_nz, int streak_nz_le3, int streak_nz_gt3);
// Builds the histogram image. // Builds the histogram image.
int VP8LGetHistoImageSymbols(int xsize, int ysize, int VP8LGetHistoImageSymbols(int xsize, int ysize,
const VP8LBackwardRefs* const refs, const VP8LBackwardRefs* const refs,