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-rw-r--r--src/enc/analysis.c214
1 files changed, 89 insertions, 125 deletions
diff --git a/src/enc/analysis.c b/src/enc/analysis.c
index 06142207..22cfb492 100644
--- a/src/enc/analysis.c
+++ b/src/enc/analysis.c
@@ -23,6 +23,10 @@ extern "C" {
#define MAX_ITERS_K_MEANS 6
+static int ClipAlpha(int alpha) {
+ return alpha < 0 ? 0 : alpha > 255 ? 255 : alpha;
+}
+
//------------------------------------------------------------------------------
// Smooth the segment map by replacing isolated block by the majority of its
// neighbours.
@@ -68,10 +72,50 @@ static void SmoothSegmentMap(VP8Encoder* const enc) {
}
//------------------------------------------------------------------------------
-// set segment susceptibility alpha_ / beta_
+// Finalize Segment probability based on the coding tree
+
+static int GetProba(int a, int b) {
+ int proba;
+ const int total = a + b;
+ if (total == 0) return 255; // that's the default probability.
+ proba = (255 * a + total / 2) / total;
+ return proba;
+}
+
+static void SetSegmentProbas(VP8Encoder* const enc) {
+ int p[NUM_MB_SEGMENTS] = { 0 };
+ int n;
+
+ for (n = 0; n < enc->mb_w_ * enc->mb_h_; ++n) {
+ const VP8MBInfo* const mb = &enc->mb_info_[n];
+ p[mb->segment_]++;
+ }
+ if (enc->pic_->stats) {
+ for (n = 0; n < NUM_MB_SEGMENTS; ++n) {
+ enc->pic_->stats->segment_size[n] = p[n];
+ }
+ }
+ if (enc->segment_hdr_.num_segments_ > 1) {
+ uint8_t* const probas = enc->proba_.segments_;
+ probas[0] = GetProba(p[0] + p[1], p[2] + p[3]);
+ probas[1] = GetProba(p[0], p[1]);
+ probas[2] = GetProba(p[2], p[3]);
+
+ enc->segment_hdr_.update_map_ =
+ (probas[0] != 255) || (probas[1] != 255) || (probas[2] != 255);
+ enc->segment_hdr_.size_ =
+ p[0] * (VP8BitCost(0, probas[0]) + VP8BitCost(0, probas[1])) +
+ p[1] * (VP8BitCost(0, probas[0]) + VP8BitCost(1, probas[1])) +
+ p[2] * (VP8BitCost(1, probas[0]) + VP8BitCost(0, probas[2])) +
+ p[3] * (VP8BitCost(1, probas[0]) + VP8BitCost(1, probas[2]));
+ } else {
+ enc->segment_hdr_.update_map_ = 0;
+ enc->segment_hdr_.size_ = 0;
+ }
+}
static WEBP_INLINE int clip(int v, int m, int M) {
- return (v < m) ? m : (v > M) ? M : v;
+ return v < m ? m : v > M ? M : v;
}
static void SetSegmentAlphas(VP8Encoder* const enc,
@@ -98,63 +142,22 @@ static void SetSegmentAlphas(VP8Encoder* const enc,
}
//------------------------------------------------------------------------------
-// Compute susceptibility based on DCT-coeff histograms:
-// the higher, the "easier" the macroblock is to compress.
-
-#define MAX_ALPHA 255 // 8b of precision for susceptibilities.
-#define ALPHA_SCALE (2 * MAX_ALPHA) // scaling factor for alpha.
-#define DEFAULT_ALPHA (-1)
-#define IS_BETTER_ALPHA(alpha, best_alpha) ((alpha) > (best_alpha))
-
-static int FinalAlphaValue(int alpha) {
- alpha = MAX_ALPHA - alpha;
- return clip(alpha, 0, MAX_ALPHA);
-}
-
-static int GetAlpha(const VP8Histogram* const histo) {
- int max_value = 0, last_non_zero = 1;
- int k;
- int alpha;
- for (k = 0; k <= MAX_COEFF_THRESH; ++k) {
- const int value = histo->distribution[k];
- if (value > 0) {
- if (value > max_value) max_value = value;
- last_non_zero = k;
- }
- }
- // 'alpha' will later be clipped to [0..MAX_ALPHA] range, clamping outer
- // values which happen to be mostly noise. This leaves the maximum precision
- // for handling the useful small values which contribute most.
- alpha = (max_value > 1) ? ALPHA_SCALE * last_non_zero / max_value : 0;
- return alpha;
-}
-
-static void MergeHistograms(const VP8Histogram* const in,
- VP8Histogram* const out) {
- int i;
- for (i = 0; i <= MAX_COEFF_THRESH; ++i) {
- out->distribution[i] += in->distribution[i];
- }
-}
-
-//------------------------------------------------------------------------------
// Simplified k-Means, to assign Nb segments based on alpha-histogram
-static void AssignSegments(VP8Encoder* const enc,
- const int alphas[MAX_ALPHA + 1]) {
+static void AssignSegments(VP8Encoder* const enc, const int alphas[256]) {
const int nb = enc->segment_hdr_.num_segments_;
int centers[NUM_MB_SEGMENTS];
int weighted_average = 0;
- int map[MAX_ALPHA + 1];
+ int map[256];
int a, n, k;
- int min_a = 0, max_a = MAX_ALPHA, range_a;
+ int min_a = 0, max_a = 255, range_a;
// 'int' type is ok for histo, and won't overflow
int accum[NUM_MB_SEGMENTS], dist_accum[NUM_MB_SEGMENTS];
// bracket the input
- for (n = 0; n <= MAX_ALPHA && alphas[n] == 0; ++n) {}
+ for (n = 0; n < 256 && alphas[n] == 0; ++n) {}
min_a = n;
- for (n = MAX_ALPHA; n > min_a && alphas[n] == 0; --n) {}
+ for (n = 255; n > min_a && alphas[n] == 0; --n) {}
max_a = n;
range_a = max_a - min_a;
@@ -207,7 +210,7 @@ static void AssignSegments(VP8Encoder* const enc,
VP8MBInfo* const mb = &enc->mb_info_[n];
const int alpha = mb->alpha_;
mb->segment_ = map[alpha];
- mb->alpha_ = centers[map[alpha]]; // for the record.
+ mb->alpha_ = centers[map[alpha]]; // just for the record.
}
if (nb > 1) {
@@ -215,6 +218,7 @@ static void AssignSegments(VP8Encoder* const enc,
if (smooth) SmoothSegmentMap(enc);
}
+ SetSegmentProbas(enc); // Assign final proba
SetSegmentAlphas(enc, centers, weighted_average); // pick some alphas.
}
@@ -232,19 +236,15 @@ static void AssignSegments(VP8Encoder* const enc,
static int MBAnalyzeBestIntra16Mode(VP8EncIterator* const it) {
const int max_mode = (it->enc_->method_ >= 3) ? MAX_INTRA16_MODE : 4;
int mode;
- int best_alpha = DEFAULT_ALPHA;
+ int best_alpha = -1;
int best_mode = 0;
VP8MakeLuma16Preds(it);
for (mode = 0; mode < max_mode; ++mode) {
- VP8Histogram histo = { { 0 } };
- int alpha;
-
- VP8CollectHistogram(it->yuv_in_ + Y_OFF,
- it->yuv_p_ + VP8I16ModeOffsets[mode],
- 0, 16, &histo);
- alpha = GetAlpha(&histo);
- if (IS_BETTER_ALPHA(alpha, best_alpha)) {
+ const int alpha = VP8CollectHistogram(it->yuv_in_ + Y_OFF,
+ it->yuv_p_ + VP8I16ModeOffsets[mode],
+ 0, 16);
+ if (alpha > best_alpha) {
best_alpha = alpha;
best_mode = mode;
}
@@ -257,58 +257,45 @@ static int MBAnalyzeBestIntra4Mode(VP8EncIterator* const it,
int best_alpha) {
uint8_t modes[16];
const int max_mode = (it->enc_->method_ >= 3) ? MAX_INTRA4_MODE : NUM_BMODES;
- int i4_alpha;
- VP8Histogram total_histo = { { 0 } };
- int cur_histo = 0;
-
+ int i4_alpha = 0;
VP8IteratorStartI4(it);
do {
int mode;
- int best_mode_alpha = DEFAULT_ALPHA;
- VP8Histogram histos[2];
+ int best_mode_alpha = -1;
const uint8_t* const src = it->yuv_in_ + Y_OFF + VP8Scan[it->i4_];
VP8MakeIntra4Preds(it);
for (mode = 0; mode < max_mode; ++mode) {
- int alpha;
-
- memset(&histos[cur_histo], 0, sizeof(histos[cur_histo]));
- VP8CollectHistogram(src, it->yuv_p_ + VP8I4ModeOffsets[mode],
- 0, 1, &histos[cur_histo]);
- alpha = GetAlpha(&histos[cur_histo]);
- if (IS_BETTER_ALPHA(alpha, best_mode_alpha)) {
+ const int alpha = VP8CollectHistogram(src,
+ it->yuv_p_ + VP8I4ModeOffsets[mode],
+ 0, 1);
+ if (alpha > best_mode_alpha) {
best_mode_alpha = alpha;
modes[it->i4_] = mode;
- cur_histo ^= 1; // keep track of best histo so far.
}
}
- // accumulate best histogram
- MergeHistograms(&histos[cur_histo ^ 1], &total_histo);
+ i4_alpha += best_mode_alpha;
// Note: we reuse the original samples for predictors
} while (VP8IteratorRotateI4(it, it->yuv_in_ + Y_OFF));
- i4_alpha = GetAlpha(&total_histo);
- if (IS_BETTER_ALPHA(i4_alpha, best_alpha)) {
+ if (i4_alpha > best_alpha) {
VP8SetIntra4Mode(it, modes);
- best_alpha = i4_alpha;
+ best_alpha = ClipAlpha(i4_alpha);
}
return best_alpha;
}
static int MBAnalyzeBestUVMode(VP8EncIterator* const it) {
- int best_alpha = DEFAULT_ALPHA;
+ int best_alpha = -1;
int best_mode = 0;
const int max_mode = (it->enc_->method_ >= 3) ? MAX_UV_MODE : 4;
int mode;
VP8MakeChroma8Preds(it);
for (mode = 0; mode < max_mode; ++mode) {
- VP8Histogram histo = { { 0 } };
- int alpha;
- VP8CollectHistogram(it->yuv_in_ + U_OFF,
- it->yuv_p_ + VP8UVModeOffsets[mode],
- 16, 16 + 4 + 4, &histo);
- alpha = GetAlpha(&histo);
- if (IS_BETTER_ALPHA(alpha, best_alpha)) {
+ const int alpha = VP8CollectHistogram(it->yuv_in_ + U_OFF,
+ it->yuv_p_ + VP8UVModeOffsets[mode],
+ 16, 16 + 4 + 4);
+ if (alpha > best_alpha) {
best_alpha = alpha;
best_mode = mode;
}
@@ -318,7 +305,7 @@ static int MBAnalyzeBestUVMode(VP8EncIterator* const it) {
}
static void MBAnalyze(VP8EncIterator* const it,
- int alphas[MAX_ALPHA + 1], int* const uv_alpha) {
+ int alphas[256], int* const uv_alpha) {
const VP8Encoder* const enc = it->enc_;
int best_alpha, best_uv_alpha;
@@ -337,19 +324,10 @@ static void MBAnalyze(VP8EncIterator* const it,
best_uv_alpha = MBAnalyzeBestUVMode(it);
// Final susceptibility mix
- best_alpha = (3 * best_alpha + best_uv_alpha + 2) >> 2;
- best_alpha = FinalAlphaValue(best_alpha);
+ best_alpha = (best_alpha + best_uv_alpha + 1) / 2;
alphas[best_alpha]++;
*uv_alpha += best_uv_alpha;
- it->mb_->alpha_ = best_alpha; // for later remapping.
-}
-
-static void DefaultMBInfo(VP8MBInfo* const mb) {
- mb->type_ = 1; // I16x16
- mb->uv_mode_ = 0;
- mb->skip_ = 0; // not skipped
- mb->segment_ = 0; // default segment
- mb->alpha_ = 0;
+ it->mb_->alpha_ = best_alpha; // Informative only.
}
//------------------------------------------------------------------------------
@@ -364,34 +342,20 @@ static void DefaultMBInfo(VP8MBInfo* const mb) {
int VP8EncAnalyze(VP8Encoder* const enc) {
int ok = 1;
- const int do_segments =
- (enc->segment_hdr_.num_segments_ > 1) ||
- (enc->method_ <= 2); // for methods 0,1,2, we need preds_[] to be filled.
- if (do_segments) {
- int alphas[MAX_ALPHA + 1] = { 0 };
- VP8EncIterator it;
-
- VP8IteratorInit(enc, &it);
- enc->uv_alpha_ = 0;
- do {
- VP8IteratorImport(&it);
- MBAnalyze(&it, alphas, &enc->uv_alpha_);
- ok = VP8IteratorProgress(&it, 20);
- // Let's pretend we have perfect lossless reconstruction.
- } while (ok && VP8IteratorNext(&it, it.yuv_in_));
- enc->uv_alpha_ /= enc->mb_w_ * enc->mb_h_;
- if (ok) AssignSegments(enc, alphas);
- } else { // Use only one default segment.
- int n;
- for (n = 0; n < enc->mb_w_ * enc->mb_h_; ++n) {
- DefaultMBInfo(&enc->mb_info_[n]);
- }
- // Default susceptibilities.
- enc->dqm_[0].alpha_ = 0;
- enc->dqm_[0].beta_ = 0;
- enc->uv_alpha_ = 0; // we can't compute this one.
- WebPReportProgress(enc->pic_, enc->percent_ + 20, &enc->percent_);
- }
+ int alphas[256] = { 0 };
+ VP8EncIterator it;
+
+ VP8IteratorInit(enc, &it);
+ enc->uv_alpha_ = 0;
+ do {
+ VP8IteratorImport(&it);
+ MBAnalyze(&it, alphas, &enc->uv_alpha_);
+ ok = VP8IteratorProgress(&it, 20);
+ // Let's pretend we have perfect lossless reconstruction.
+ } while (ok && VP8IteratorNext(&it, it.yuv_in_));
+ enc->uv_alpha_ /= enc->mb_w_ * enc->mb_h_;
+ if (ok) AssignSegments(enc, alphas);
+
return ok;
}
generated by cgit v1.2.3 (git 2.25.1) at 2024-07-25 06:41:43 +0000