diff --git a/src/enc/quant.c b/src/enc/quant.c index 24143abf..da2fc554 100644 --- a/src/enc/quant.c +++ b/src/enc/quant.c @@ -515,15 +515,18 @@ static void AddScore(VP8ModeScore* const dst, const VP8ModeScore* const src) { //------------------------------------------------------------------------------ // Performs trellis-optimized quantization. -// Trellis - +// Trellis node +typedef struct { + int8_t prev; // best previous node + int8_t sign; // sign of coeff_i + int16_t level; // level +} Node; + +// Score state typedef struct { - int prev; // best previous node - int level; // level - int sign; // sign of coeff_i score_t score; // partial RD score const uint16_t* costs; // shortcut to cost tables -} Node; +} ScoreState; // If a coefficient was quantized to a value Q (using a neutral bias), // we test all alternate possibilities between [Q-MIN_DELTA, Q+MAX_DELTA] @@ -531,7 +534,8 @@ typedef struct { #define MIN_DELTA 0 // how much lower level to try #define MAX_DELTA 1 // how much higher #define NUM_NODES (MIN_DELTA + 1 + MAX_DELTA) -#define NODE(n, l) (nodes[(n) + 1][(l) + MIN_DELTA]) +#define NODE(n, l) (nodes[(n)][(l) + MIN_DELTA]) +#define SCORE_STATE(n, l) (score_states[n][(l) + MIN_DELTA]) static WEBP_INLINE void SetRDScore(int lambda, VP8ModeScore* const rd) { // TODO: incorporate the "* 256" in the tables? @@ -551,7 +555,10 @@ static int TrellisQuantizeBlock(const VP8Encoder* const enc, const ProbaArray* const probas = enc->proba_.coeffs_[coeff_type]; const CostArray* const costs = enc->proba_.level_cost_[coeff_type]; const int first = (coeff_type == 0) ? 1 : 0; - Node nodes[17][NUM_NODES]; + Node nodes[16][NUM_NODES]; + ScoreState score_states[2][NUM_NODES]; + ScoreState* ss_cur = &SCORE_STATE(0, MIN_DELTA); + ScoreState* ss_prev = &SCORE_STATE(1, MIN_DELTA); int best_path[3] = {-1, -1, -1}; // store best-last/best-level/best-previous score_t best_score; int n, m, p, last; @@ -580,11 +587,10 @@ static int TrellisQuantizeBlock(const VP8Encoder* const enc, best_score = RDScoreTrellis(lambda, cost, 0); // initialize source node. - n = first - 1; for (m = -MIN_DELTA; m <= MAX_DELTA; ++m) { const score_t rate = (ctx0 == 0) ? VP8BitCost(1, last_proba) : 0; - NODE(n, m).score = RDScoreTrellis(lambda, rate, 0); - NODE(n, m).costs = costs[VP8EncBands[first]][ctx0]; + ss_cur[m].score = RDScoreTrellis(lambda, rate, 0); + ss_cur[m].costs = costs[VP8EncBands[first]][ctx0]; } } @@ -601,25 +607,34 @@ static int TrellisQuantizeBlock(const VP8Encoder* const enc, int level0 = QUANTDIV(coeff0, iQ, B); if (level0 > MAX_LEVEL) level0 = MAX_LEVEL; + { // Swap current and previous score states + ScoreState* const tmp = ss_cur; + ss_cur = ss_prev; + ss_prev = tmp; + } + // test all alternate level values around level0. for (m = -MIN_DELTA; m <= MAX_DELTA; ++m) { Node* const cur = &NODE(n, m); int level = level0 + m; const int ctx = (level > 2) ? 2 : level; const int band = VP8EncBands[n + 1]; - score_t base_score, last_pos_cost; + score_t base_score, last_pos_score; + score_t best_cur_score = MAX_COST; + int best_prev = 0; // default, in case - cur->score = MAX_COST; + ss_cur[m].score = MAX_COST; + ss_cur[m].costs = costs[band][ctx]; if (level > MAX_LEVEL || level < 0) { // node is dead? continue; } - cur->sign = sign; - cur->level = level; - cur->costs = costs[band][ctx]; - cur->prev = 0; // default, in case // Compute extra rate cost if last coeff's position is < 15 - last_pos_cost = (n < 15) ? VP8BitCost(0, probas[band][ctx][0]) : 0; + { + const score_t last_pos_cost = + (n < 15) ? VP8BitCost(0, probas[band][ctx][0]) : 0; + last_pos_score = RDScoreTrellis(lambda, last_pos_cost, 0); + } { // Compute delta_error = how much coding this level will @@ -633,29 +648,31 @@ static int TrellisQuantizeBlock(const VP8Encoder* const enc, // Inspect all possible non-dead predecessors. Retain only the best one. for (p = -MIN_DELTA; p <= MAX_DELTA; ++p) { - const Node* const prev = &NODE(n - 1, p); - if (prev->score < MAX_COST) { // skip dead node - // Base cost of both terminal / non-terminal hypothesis - const score_t cost = VP8LevelCost(prev->costs, level); - // Examine node assuming it's a non-terminal one. - const score_t score = - base_score + prev->score + RDScoreTrellis(lambda, cost, 0); - if (score < cur->score) { - cur->score = score; - cur->prev = p; - } + // Dead nodes (with ss_prev[p].score >= MAX_COST) are automatically + // eliminated since their score can't be better than the current best. + const score_t cost = VP8LevelCost(ss_prev[p].costs, level); + // Examine node assuming it's a non-terminal one. + const score_t score = + base_score + ss_prev[p].score + RDScoreTrellis(lambda, cost, 0); + if (score < best_cur_score) { + best_cur_score = score; + best_prev = p; } } + // Store best finding in current node. + cur->sign = sign; + cur->level = level; + cur->prev = best_prev; + ss_cur[m].score = best_cur_score; + // Now, record best terminal node (and thus best entry in the graph). - if (cur->level != 0) { - const score_t last_pos_score = - RDScoreTrellis(lambda, last_pos_cost, 0); - const score_t score = cur->score + last_pos_score; + if (level != 0) { + const score_t score = best_cur_score + last_pos_score; if (score < best_score) { best_score = score; best_path[0] = n; // best eob position - best_path[1] = cur->level - level0; // best node index ('m') - best_path[2] = cur->prev; // best predecessor + best_path[1] = m; // best node index + best_path[2] = best_prev; // best predecessor } } } diff --git a/src/enc/vp8enci.h b/src/enc/vp8enci.h index 08a636ad..7d7f262f 100644 --- a/src/enc/vp8enci.h +++ b/src/enc/vp8enci.h @@ -160,6 +160,8 @@ extern const int VP8I4ModeOffsets[NUM_BMODES]; #define I4TMP (6 * 16 * BPS + 8 * BPS + 8) typedef int64_t score_t; // type used for scores, rate, distortion +// Note that MAX_COST is not the maximum allowed by sizeof(score_t), +// in order to allow overflowing computations. #define MAX_COST ((score_t)0x7fffffffffffffLL) #define QFIX 17