dany/libwebp
1
0
Fork 0
mirror of https://github.com/webmproject/libwebp.git synced 2024-11-20 04:18:26 +01:00
Code Issues Actions Packages Projects Releases Wiki Activity

Merge "WIP: extract the float-calculation of HuffmanCost from loop"

Browse Source
This commit is contained in:
skal 2014-04-15 11:33:11 -07:00 committed by Gerrit Code Review
commit a9fc697cb6
2 changed files with 39 additions and 27 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

59
src/enc/histogram.c
View File

@ -188,59 +188,64 @@ static WEBP_INLINE double InitialHuffmanCost(void) {
return kHuffmanCodeOfHuffmanCodeSize - kSmallBias;
}
static WEBP_INLINE double HuffmanCostRefine(int streak, int val) {
double retval;
if (streak > 3) {
if (val == 0) {
retval = 1.5625 + 0.234375 * streak;
} else {
retval = 2.578125 + 0.703125 * streak;
}
} else {
if (val == 0) {
retval = 1.796875 * streak;
} else {
retval = 3.28125 * streak;
}
}
double VP8FinalHuffmanCost(int cnt_z, int streak_z_le3, int streak_z_gt3,
int cnt_nz, int streak_nz_le3, int streak_nz_gt3) {
double retval = InitialHuffmanCost();
retval += cnt_z * 1.5625 + 0.234375 * streak_z_gt3;
retval += cnt_nz * 2.578125 + 0.703125 * streak_nz_gt3;
retval += 1.796875 * streak_z_le3;
retval += 3.28125 * streak_nz_le3;
return retval;
}
// Returns the cost encode the rle-encoded entropy code.
// The constants in this function are experimental.
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 i = 0;
double retval = InitialHuffmanCost();
for (; i < length - 1; ++i) {
int i;
for (i = 0; i < length - 1; ++i) {
++streak;
if (population[i] == population[i + 1]) {
continue;
}
retval += HuffmanCostRefine(streak, population[i]);
cnts[population[i] != 0] += (streak > 3);
streaks[population[i] != 0][(streak > 3)] += streak;
streak = 0;
}
retval += HuffmanCostRefine(++streak, population[i]);
return retval;
++streak;
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,
int length) {
int cnts[2] = { 0, 0 };
int streaks[2][2] = { { 0, 0 }, { 0, 0 } };
int streak = 0;
int i = 0;
double retval = InitialHuffmanCost();
for (; i < length - 1; ++i) {
int i;
for (i = 0; i < length - 1; ++i) {
const int xy = X[i] + Y[i];
const int xy_next = X[i + 1] + Y[i + 1];
++streak;
if (xy == xy_next) {
continue;
}
retval += HuffmanCostRefine(streak, xy);
cnts[xy != 0] += (streak > 3);
streaks[xy != 0][streak > 3] += streak;
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) {

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);
}
// 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.
int VP8LGetHistoImageSymbols(int xsize, int ysize,
const VP8LBackwardRefs* const refs,