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Tune Lossless encoder
- Changed the dynamic range where more aggressive (BackwardReferencesTraceBackward) heuristic is run from quality > 10 (instead of quality > 25). - Limit the backward-ref Window size to 16*width & 256*width for lower qualities ([0, 25[ & [25, 50[) respectively, instead of 1M window. - Evaluate the params for HashChainFindCopy outside this function call and pass it, instead of recomputing them for every call. Change-Id: If9eedfc14b978e7632d7cf69c96186e2910b0554
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@ -141,9 +141,25 @@ static void HashChainInsert(HashChain* const p,
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p->hash_to_first_index_[hash_code] = pos;
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p->hash_to_first_index_[hash_code] = pos;
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}
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}
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static void GetParamsForHashChainFindCopy(int quality, int xsize,
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int* window_size, int* iter_pos,
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int* iter_limit) {
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const int iter_mult = (quality < 27) ? 1 : 1 + ((quality - 27) >> 4);
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// Limit the backward-ref window size for lower qualities.
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const int max_window_size = (quality > 50) ? WINDOW_SIZE
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: (quality > 25) ? (xsize << 8)
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: (xsize << 4);
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assert(xsize > 0);
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*window_size = (max_window_size > WINDOW_SIZE) ? WINDOW_SIZE
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: max_window_size;
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*iter_pos = 5 + (quality >> 3);
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*iter_limit = -quality * iter_mult;
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}
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static int HashChainFindCopy(const HashChain* const p,
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static int HashChainFindCopy(const HashChain* const p,
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int quality, int index, int xsize,
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int index, int xsize,
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const uint32_t* const argb, int maxlen,
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const uint32_t* const argb, int maxlen,
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int window_size, int iter_pos, int iter_limit,
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int* const distance_ptr,
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int* const distance_ptr,
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int* const length_ptr) {
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int* const length_ptr) {
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const uint64_t hash_code = GetPixPairHash64(&argb[index]);
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const uint64_t hash_code = GetPixPairHash64(&argb[index]);
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@ -152,10 +168,7 @@ static int HashChainFindCopy(const HashChain* const p,
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int best_length = 0;
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int best_length = 0;
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int best_distance = 0;
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int best_distance = 0;
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const uint32_t* const argb_start = argb + index;
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const uint32_t* const argb_start = argb + index;
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const int iter_min_mult = (quality < 36) ? 1 : 1 + ((quality - 36) >> 3);
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const int min_pos = (index > window_size) ? index - window_size : 0;
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const int iter_min = -quality * iter_min_mult;
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int iter_cnt = 10 + (quality >> 2);
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const int min_pos = (index > WINDOW_SIZE) ? index - WINDOW_SIZE : 0;
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int pos;
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int pos;
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assert(xsize > 0);
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assert(xsize > 0);
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@ -164,12 +177,12 @@ static int HashChainFindCopy(const HashChain* const p,
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pos = p->chain_[pos]) {
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pos = p->chain_[pos]) {
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int64_t val;
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int64_t val;
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int curr_length;
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int curr_length;
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if (iter_cnt < 0) {
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if (iter_pos < 0) {
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if (iter_cnt < iter_min || best_val >= 0xff0000) {
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if (iter_pos < iter_limit || best_val >= 0xff0000) {
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break;
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break;
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}
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}
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}
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}
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--iter_cnt;
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--iter_pos;
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if (best_length != 0 &&
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if (best_length != 0 &&
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argb[pos + best_length - 1] != argb_start[best_length - 1]) {
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argb[pos + best_length - 1] != argb_start[best_length - 1]) {
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continue;
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continue;
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@ -257,6 +270,9 @@ static int BackwardReferencesHashChain(int xsize, int ysize,
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const int pix_count = xsize * ysize;
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const int pix_count = xsize * ysize;
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HashChain* const hash_chain = (HashChain*)malloc(sizeof(*hash_chain));
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HashChain* const hash_chain = (HashChain*)malloc(sizeof(*hash_chain));
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VP8LColorCache hashers;
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VP8LColorCache hashers;
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int window_size = WINDOW_SIZE;
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int iter_pos = 1;
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int iter_limit = -1;
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if (hash_chain == NULL) return 0;
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if (hash_chain == NULL) return 0;
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if (use_color_cache) {
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if (use_color_cache) {
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@ -267,6 +283,8 @@ static int BackwardReferencesHashChain(int xsize, int ysize,
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if (!HashChainInit(hash_chain, pix_count)) goto Error;
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if (!HashChainInit(hash_chain, pix_count)) goto Error;
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refs->size = 0;
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refs->size = 0;
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GetParamsForHashChainFindCopy(quality, xsize, &window_size, &iter_pos,
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&iter_limit);
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for (i = 0; i < pix_count; ) {
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for (i = 0; i < pix_count; ) {
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// Alternative#1: Code the pixels starting at 'i' using backward reference.
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// Alternative#1: Code the pixels starting at 'i' using backward reference.
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int offset = 0;
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int offset = 0;
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@ -276,7 +294,8 @@ static int BackwardReferencesHashChain(int xsize, int ysize,
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if (maxlen > MAX_LENGTH) {
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if (maxlen > MAX_LENGTH) {
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maxlen = MAX_LENGTH;
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maxlen = MAX_LENGTH;
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}
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}
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HashChainFindCopy(hash_chain, quality, i, xsize, argb, maxlen,
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HashChainFindCopy(hash_chain, i, xsize, argb, maxlen,
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window_size, iter_pos, iter_limit,
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&offset, &len);
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&offset, &len);
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}
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}
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if (len >= MIN_LENGTH) {
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if (len >= MIN_LENGTH) {
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@ -291,8 +310,9 @@ static int BackwardReferencesHashChain(int xsize, int ysize,
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if (maxlen > MAX_LENGTH) {
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if (maxlen > MAX_LENGTH) {
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maxlen = MAX_LENGTH;
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maxlen = MAX_LENGTH;
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}
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}
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HashChainFindCopy(hash_chain, quality,
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HashChainFindCopy(hash_chain, i + 1, xsize, argb, maxlen,
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i + 1, xsize, argb, maxlen, &offset2, &len2);
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window_size, iter_pos, iter_limit,
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&offset2, &len2);
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if (len2 > len + 1) {
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if (len2 > len + 1) {
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const uint32_t pixel = argb[i];
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const uint32_t pixel = argb[i];
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// Alternative#2 is a better match. So push pixel at 'i' as literal.
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// Alternative#2 is a better match. So push pixel at 'i' as literal.
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@ -465,6 +485,9 @@ static int BackwardReferencesHashChainDistanceOnly(
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VP8LColorCache hashers;
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VP8LColorCache hashers;
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const double mul0 = (recursive_cost_model != 0) ? 1.0 : 0.68;
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const double mul0 = (recursive_cost_model != 0) ? 1.0 : 0.68;
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const double mul1 = (recursive_cost_model != 0) ? 1.0 : 0.82;
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const double mul1 = (recursive_cost_model != 0) ? 1.0 : 0.82;
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int window_size = WINDOW_SIZE;
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int iter_pos = 1;
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int iter_limit = -1;
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if (cost == NULL || cost_model == NULL || hash_chain == NULL) goto Error;
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if (cost == NULL || cost_model == NULL || hash_chain == NULL) goto Error;
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@ -485,6 +508,8 @@ static int BackwardReferencesHashChainDistanceOnly(
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// We loop one pixel at a time, but store all currently best points to
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// We loop one pixel at a time, but store all currently best points to
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// non-processed locations from this point.
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// non-processed locations from this point.
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dist_array[0] = 0;
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dist_array[0] = 0;
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GetParamsForHashChainFindCopy(quality, xsize, &window_size, &iter_pos,
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&iter_limit);
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for (i = 0; i < pix_count; ++i) {
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for (i = 0; i < pix_count; ++i) {
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double prev_cost = 0.0;
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double prev_cost = 0.0;
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int shortmax;
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int shortmax;
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@ -499,7 +524,8 @@ static int BackwardReferencesHashChainDistanceOnly(
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if (maxlen > pix_count - i) {
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if (maxlen > pix_count - i) {
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maxlen = pix_count - i;
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maxlen = pix_count - i;
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}
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}
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HashChainFindCopy(hash_chain, quality, i, xsize, argb, maxlen,
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HashChainFindCopy(hash_chain, i, xsize, argb, maxlen,
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window_size, iter_pos, iter_limit,
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&offset, &len);
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&offset, &len);
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}
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}
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if (len >= MIN_LENGTH) {
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if (len >= MIN_LENGTH) {
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@ -612,6 +638,9 @@ static int BackwardReferencesHashChainFollowChosenPath(
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int ix;
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int ix;
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int ok = 0;
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int ok = 0;
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int cc_init = 0;
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int cc_init = 0;
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int window_size = WINDOW_SIZE;
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int iter_pos = 1;
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int iter_limit = -1;
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HashChain* hash_chain = (HashChain*)malloc(sizeof(*hash_chain));
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HashChain* hash_chain = (HashChain*)malloc(sizeof(*hash_chain));
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VP8LColorCache hashers;
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VP8LColorCache hashers;
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@ -624,13 +653,16 @@ static int BackwardReferencesHashChainFollowChosenPath(
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}
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}
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refs->size = 0;
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refs->size = 0;
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GetParamsForHashChainFindCopy(quality, xsize, &window_size, &iter_pos,
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&iter_limit);
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for (ix = 0; ix < chosen_path_size; ++ix, ++size) {
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for (ix = 0; ix < chosen_path_size; ++ix, ++size) {
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int offset = 0;
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int offset = 0;
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int len = 0;
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int len = 0;
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int maxlen = chosen_path[ix];
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int maxlen = chosen_path[ix];
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if (maxlen != 1) {
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if (maxlen != 1) {
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HashChainFindCopy(hash_chain, quality,
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HashChainFindCopy(hash_chain, i, xsize, argb, maxlen,
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i, xsize, argb, maxlen, &offset, &len);
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window_size, iter_pos, iter_limit,
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&offset, &len);
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assert(len == maxlen);
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assert(len == maxlen);
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refs->refs[size] = PixOrCopyCreateCopy(offset, len);
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refs->refs[size] = PixOrCopyCreateCopy(offset, len);
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if (use_color_cache) {
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if (use_color_cache) {
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@ -762,8 +794,8 @@ int VP8LGetBackwardReferences(int width, int height,
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// Choose appropriate backward reference.
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// Choose appropriate backward reference.
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if (lz77_is_useful) {
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if (lz77_is_useful) {
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// TraceBackwards is costly. Don't execute it at lower quality (q <= 25).
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// TraceBackwards is costly. Don't execute it at lower quality (q <= 10).
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const int try_lz77_trace_backwards = (quality > 25);
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const int try_lz77_trace_backwards = (quality > 10);
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*best = refs_lz77; // default guess: lz77 is better
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*best = refs_lz77; // default guess: lz77 is better
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VP8LClearBackwardRefs(&refs_rle);
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VP8LClearBackwardRefs(&refs_rle);
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if (try_lz77_trace_backwards) {
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if (try_lz77_trace_backwards) {
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