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4-5% faster trellis by removing some unneeded calculations.

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(We didn't need the exact value of the max_error properly.
We can work with relative values instead of absolute)

Output is bitwise the same as before.

Change-Id: I67aeaaea5f81bfd9ca8e1158387a5083a2b6c649
This commit is contained in:
skal 2014-03-05 23:21:43 +01:00
parent 687a58ecc3
commit 30176619c6
1 changed files with 11 additions and 10 deletions
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21
src/enc/quant.c
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@ -553,22 +553,22 @@ static int TrellisQuantizeBlock(const VP8EncIterator* const it,
Node nodes[17][NUM_NODES];
int best_path[3] = {-1, -1, -1}; // store best-last/best-level/best-previous
score_t best_score;
int last = first - 1;
int n, m, p;
int n, m, p, last;
{
score_t cost;
score_t max_error;
const int thresh = mtx->q_[1] * mtx->q_[1] / 4;
const int last_proba = probas[VP8EncBands[first]][ctx0][0];
// compute maximal distortion.
max_error = 0;
for (n = first; n < 16; ++n) {
// compute the position of the last interesting coefficient
last = first - 1;
for (n = 15; n >= first; --n) {
const int j = kZigzag[n];
const int err = in[j] * in[j];
max_error += kWeightTrellis[j] * err;
if (err > thresh) last = n;
if (err > thresh) {
last = n;
break;
}
}
// we don't need to go inspect up to n = 16 coeffs. We can just go up
// to last + 1 (inclusive) without losing much.
@ -576,13 +576,13 @@ static int TrellisQuantizeBlock(const VP8EncIterator* const it,
// compute 'skip' score. This is the max score one can do.
cost = VP8BitCost(0, last_proba);
best_score = RDScoreTrellis(lambda, cost, max_error);
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, max_error);
NODE(n, m).score = RDScoreTrellis(lambda, rate, 0);
NODE(n, m).costs = costs[VP8EncBands[first]][ctx0];
}
}
@ -615,6 +615,7 @@ static int TrellisQuantizeBlock(const VP8EncIterator* const it,
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;