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replace unneeded calls to HistogramCopy() by swaps

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most of the time, we don't need to actually move the
data.

Compression is randomly slightly different, because HistogramCompactBins() changed.
Timing is about the same.

Change-Id: Ia6af8e9780581014d6860f2b546189ac817cfad1
This commit is contained in:
Pascal Massimino 2014-12-17 15:31:22 +01:00
parent e66a9225f3
commit 24284459c7
3 changed files with 60 additions and 53 deletions
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99
src/enc/histogram.c
View File

@ -39,6 +39,13 @@ static void HistogramClear(VP8LHistogram* const p) {
p->literal_ = literal;
}
// Swap two histogram pointers.
static void HistogramSwap(VP8LHistogram** const A, VP8LHistogram** const B) {
VP8LHistogram* const tmp = *A;
*A = *B;
*B = tmp;
}
static void HistogramCopy(const VP8LHistogram* const src,
VP8LHistogram* const dst) {
uint32_t* const dst_literal = dst->literal_;
@ -365,39 +372,29 @@ static void HistogramAnalyzeEntropyBin(
}
}
// Compact the histogram set by moving the valid one left in the set to the
// head and moving the ones that have been merged to other histograms towards
// the end.
// Compact the histogram set by removing unused entries.
static void HistogramCompactBins(VP8LHistogramSet* const image_histo) {
int start = 0;
int end = image_histo->size - 1;
VP8LHistogram** const histograms = image_histo->histograms;
while (start < end) {
while (start <= end && histograms[start] != NULL &&
histograms[start]->bit_cost_ != 0.) {
++start;
}
while (start <= end && histograms[end]->bit_cost_ == 0.) {
histograms[end] = NULL;
--end;
}
if (start < end) {
assert(histograms[start] != NULL);
assert(histograms[end] != NULL);
HistogramCopy(histograms[end], histograms[start]);
histograms[end] = NULL;
--end;
int i, j;
for (i = 0, j = 0; i < image_histo->size; ++i) {
if (histograms[i] != NULL && histograms[i]->bit_cost_ != 0.) {
if (j < i) {
histograms[j] = histograms[i];
histograms[i] = NULL;
}
++j;
}
}
image_histo->size = end + 1;
image_histo->size = j;
}
static void HistogramCombineEntropyBin(VP8LHistogramSet* const image_histo,
VP8LHistogram* const histos,
int16_t* const bin_map, int bin_depth,
double combine_cost_factor) {
static VP8LHistogram* HistogramCombineEntropyBin(
VP8LHistogramSet* const image_histo,
VP8LHistogram* cur_combo,
int16_t* const bin_map, int bin_depth,
double combine_cost_factor) {
int bin_id;
VP8LHistogram* cur_combo = histos;
VP8LHistogram** const histograms = image_histo->histograms;
for (bin_id = 0; bin_id < BIN_SIZE; ++bin_id) {
@ -426,7 +423,7 @@ static void HistogramCombineEntropyBin(VP8LHistogramSet* const image_histo,
(histograms[idx2]->trivial_symbol_ == VP8L_NON_TRIVIAL_SYM));
const int max_combine_failures = 32;
if (try_combine || (num_combine_failures >= max_combine_failures)) {
HistogramCopy(cur_combo, histograms[idx1]);
HistogramSwap(&cur_combo, &histograms[idx1]);
histograms[idx2]->bit_cost_ = 0.;
} else {
++num_combine_failures;
@ -436,6 +433,7 @@ static void HistogramCombineEntropyBin(VP8LHistogramSet* const image_histo,
}
}
HistogramCompactBins(image_histo);
return cur_combo;
}
static uint32_t MyRand(uint32_t *seed) {
@ -658,8 +656,8 @@ static int HistogramCombineGreedy(VP8LHistogramSet* const image_histo,
}
// Move remaining histograms to the beginning of the array.
for (i = 0; i < image_histo_size; ++i) {
if (i != clusters[i]) {
HistogramCopy(histograms[clusters[i]], histograms[i]);
if (i != clusters[i]) { // swap the two histograms
HistogramSwap(&histograms[i], &histograms[clusters[i]]);
}
}
@ -672,9 +670,11 @@ static int HistogramCombineGreedy(VP8LHistogramSet* const image_histo,
return ok;
}
static void HistogramCombineStochastic(VP8LHistogramSet* const image_histo,
VP8LHistogramSet* const histos,
int quality, int min_cluster_size) {
static VP8LHistogram*HistogramCombineStochastic(
VP8LHistogramSet* const image_histo,
VP8LHistogram* tmp_histo,
VP8LHistogram* best_combo,
int quality, int min_cluster_size) {
int iter;
uint32_t seed = 0;
int tries_with_no_success = 0;
@ -684,8 +684,6 @@ static void HistogramCombineStochastic(VP8LHistogramSet* const image_histo,
const int num_pairs = image_histo_size / 2;
const int num_tries_no_success = outer_iters / 2;
VP8LHistogram** const histograms = image_histo->histograms;
VP8LHistogram* cur_combo = histos->histograms[0]; // trial histogram
VP8LHistogram* best_combo = histos->histograms[1]; // best histogram so far
// Collapse similar histograms in 'image_histo'.
++min_cluster_size;
@ -712,13 +710,9 @@ static void HistogramCombineStochastic(VP8LHistogramSet* const image_histo,
// Calculate cost reduction on combining.
curr_cost_diff = HistogramAddEval(histograms[idx1], histograms[idx2],
cur_combo, best_cost_diff);
tmp_histo, best_cost_diff);
if (curr_cost_diff < best_cost_diff) { // found a better pair?
{ // swap cur/best combo histograms
VP8LHistogram* const tmp_histo = cur_combo;
cur_combo = best_combo;
best_combo = tmp_histo;
}
HistogramSwap(&best_combo, &tmp_histo);
best_cost_diff = curr_cost_diff;
best_idx1 = idx1;
best_idx2 = idx2;
@ -726,11 +720,11 @@ static void HistogramCombineStochastic(VP8LHistogramSet* const image_histo,
}
if (best_idx1 >= 0) {
HistogramCopy(best_combo, histograms[best_idx1]);
HistogramSwap(&best_combo, &histograms[best_idx1]);
// swap best_idx2 slot with last one (which is now unused)
--image_histo_size;
if (best_idx2 != image_histo_size) {
HistogramCopy(histograms[image_histo_size], histograms[best_idx2]);
HistogramSwap(&histograms[image_histo_size], &histograms[best_idx2]);
histograms[image_histo_size] = NULL;
}
tries_with_no_success = 0;
@ -740,6 +734,7 @@ static void HistogramCombineStochastic(VP8LHistogramSet* const image_histo,
}
}
image_histo->size = image_histo_size;
return best_combo;
}
// -----------------------------------------------------------------------------
@ -804,6 +799,7 @@ int VP8LGetHistoImageSymbols(int xsize, int ysize,
const VP8LBackwardRefs* const refs,
int quality, int histo_bits, int cache_bits,
VP8LHistogramSet* const image_histo,
VP8LHistogramSet* const tmp_histos,
uint16_t* const histogram_symbols) {
int ok = 0;
const int histo_xsize = histo_bits ? VP8LSubSampleSize(xsize, histo_bits) : 1;
@ -817,13 +813,11 @@ int VP8LGetHistoImageSymbols(int xsize, int ysize,
// bin_map[n][num_histo + 1] ... bin_map[n][bin_depth - 1] = unused indices.
const int bin_depth = image_histo_raw_size + 1;
int16_t* bin_map = NULL;
VP8LHistogramSet* const histos = VP8LAllocateHistogramSet(2, cache_bits);
VP8LHistogramSet* const orig_histo =
VP8LAllocateHistogramSet(image_histo_raw_size, cache_bits);
VP8LHistogram* cur_combo;
if (orig_histo == NULL || histos == NULL) {
goto Error;
}
if (orig_histo == NULL) goto Error;
// Don't attempt linear bin-partition heuristic for:
// histograms of small sizes, as bin_map will be very sparse and;
@ -839,22 +833,26 @@ int VP8LGetHistoImageSymbols(int xsize, int ysize,
// Copies the histograms and computes its bit_cost.
HistogramCopyAndAnalyze(orig_histo, image_histo);
cur_combo = tmp_histos->histograms[1]; // pick up working slot
if (bin_map != NULL) {
const double combine_cost_factor =
GetCombineCostFactor(image_histo_raw_size, quality);
HistogramAnalyzeEntropyBin(orig_histo, bin_map);
// Collapse histograms with similar entropy.
HistogramCombineEntropyBin(image_histo, histos->histograms[0],
bin_map, bin_depth, combine_cost_factor);
cur_combo =
HistogramCombineEntropyBin(image_histo, cur_combo,
bin_map, bin_depth, combine_cost_factor);
}
{
const float x = quality / 100.f;
// cubic ramp between 1 and MAX_HISTO_GREEDY:
const int threshold_size = (int)(1 + (x * x * x) * (MAX_HISTO_GREEDY - 1));
HistogramCombineStochastic(image_histo, histos, quality, threshold_size);
cur_combo = HistogramCombineStochastic(image_histo,
tmp_histos->histograms[0],
cur_combo, quality, threshold_size);
if ((image_histo->size <= threshold_size) &&
!HistogramCombineGreedy(image_histo, histos->histograms[0])) {
!HistogramCombineGreedy(image_histo, cur_combo)) {
goto Error;
}
}
@ -867,6 +865,5 @@ int VP8LGetHistoImageSymbols(int xsize, int ysize,
Error:
WebPSafeFree(bin_map);
VP8LFreeHistogramSet(orig_histo);
VP8LFreeHistogramSet(histos);
return ok;
}

1
src/enc/histogram.h
View File

@ -103,6 +103,7 @@ int VP8LGetHistoImageSymbols(int xsize, int ysize,
const VP8LBackwardRefs* const refs,
int quality, int histogram_bits, int cache_bits,
VP8LHistogramSet* const image_in,
VP8LHistogramSet* const tmp_histos,
uint16_t* const histogram_symbols);
#ifdef __cplusplus

13
src/enc/vp8l.c
View File

@ -758,6 +758,7 @@ static WebPEncodingError EncodeImageInternal(VP8LBitWriter* const bw,
VP8LSubSampleSize(width, histogram_bits) *
VP8LSubSampleSize(height, histogram_bits);
VP8LHistogramSet* histogram_image = NULL;
VP8LHistogramSet* tmp_histos = NULL;
int histogram_image_size = 0;
size_t bit_array_size = 0;
HuffmanTree* huff_tree = NULL;
@ -791,14 +792,15 @@ static WebPEncodingError EncodeImageInternal(VP8LBitWriter* const bw,
}
histogram_image =
VP8LAllocateHistogramSet(histogram_image_xysize, *cache_bits);
if (histogram_image == NULL) {
tmp_histos = VP8LAllocateHistogramSet(2, *cache_bits);
if (histogram_image == NULL || tmp_histos == NULL) {
err = VP8_ENC_ERROR_OUT_OF_MEMORY;
goto Error;
}
// Build histogram image and symbols from backward references.
if (!VP8LGetHistoImageSymbols(width, height, &refs, quality, histogram_bits,
*cache_bits, histogram_image,
*cache_bits, histogram_image, tmp_histos,
histogram_symbols)) {
err = VP8_ENC_ERROR_OUT_OF_MEMORY;
goto Error;
@ -808,6 +810,8 @@ static WebPEncodingError EncodeImageInternal(VP8LBitWriter* const bw,
bit_array_size = 5 * histogram_image_size;
huffman_codes = (HuffmanTreeCode*)WebPSafeCalloc(bit_array_size,
sizeof(*huffman_codes));
// Note: some histogram_image entries may point to tmp_histos[], so the latter
// need to outlive the following call to GetHuffBitLengthsAndCodes().
if (huffman_codes == NULL ||
!GetHuffBitLengthsAndCodes(histogram_image, huffman_codes)) {
err = VP8_ENC_ERROR_OUT_OF_MEMORY;
@ -817,6 +821,10 @@ static WebPEncodingError EncodeImageInternal(VP8LBitWriter* const bw,
VP8LFreeHistogramSet(histogram_image);
histogram_image = NULL;
// Free scratch histograms.
VP8LFreeHistogramSet(tmp_histos);
tmp_histos = NULL;
// Color Cache parameters.
if (*cache_bits > 0) {
VP8LPutBits(bw, 1, 1);
@ -899,6 +907,7 @@ static WebPEncodingError EncodeImageInternal(VP8LBitWriter* const bw,
WebPSafeFree(tokens);
WebPSafeFree(huff_tree);
VP8LFreeHistogramSet(histogram_image);
VP8LFreeHistogramSet(tmp_histos);
VP8LBackwardRefsClear(&refs);
if (huffman_codes != NULL) {
WebPSafeFree(huffman_codes->codes);