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src/Source/LibWebP/src/enc/enc.analysis.c  view on Meta::CPAN

static void MBAnalyze(VP8EncIterator* const it,
                      int alphas[MAX_ALPHA + 1],
                      int* const alpha, int* const uv_alpha) {
  const VP8Encoder* const enc = it->enc_;
  int best_alpha, best_uv_alpha;

  VP8SetIntra16Mode(it, 0);  // default: Intra16, DC_PRED
  VP8SetSkip(it, 0);         // not skipped
  VP8SetSegment(it, 0);      // default segment, spec-wise.

  best_alpha = MBAnalyzeBestIntra16Mode(it);
  if (enc->method_ >= 5) {
    // We go and make a fast decision for intra4/intra16.
    // It's usually not a good and definitive pick, but helps seeding the stats
    // about level bit-cost.
    // TODO(skal): improve criterion.
    best_alpha = MBAnalyzeBestIntra4Mode(it, best_alpha);
  }
  best_uv_alpha = MBAnalyzeBestUVMode(it);

  // Final susceptibility mix
  best_alpha = (3 * best_alpha + best_uv_alpha + 2) >> 2;
  best_alpha = FinalAlphaValue(best_alpha);
  alphas[best_alpha]++;
  it->mb_->alpha_ = best_alpha;   // for later remapping.

  // Accumulate for later complexity analysis.
  *alpha += best_alpha;   // mixed susceptibility (not just luma)
  *uv_alpha += best_uv_alpha;
}

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;
}

//------------------------------------------------------------------------------
// Main analysis loop:
// Collect all susceptibilities for each macroblock and record their
// distribution in alphas[]. Segments is assigned a-posteriori, based on
// this histogram.
// We also pick an intra16 prediction mode, which shouldn't be considered
// final except for fast-encode settings. We can also pick some intra4 modes
// and decide intra4/intra16, but that's usually almost always a bad choice at
// this stage.

static void ResetAllMBInfo(VP8Encoder* const enc) {
  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;
  // Note: we can't compute this alpha_ / uv_alpha_ -> set to default value.
  enc->alpha_ = 0;
  enc->uv_alpha_ = 0;
  WebPReportProgress(enc->pic_, enc->percent_ + 20, &enc->percent_);
}

// struct used to collect job result
typedef struct {
  WebPWorker worker;
  int alphas[MAX_ALPHA + 1];
  int alpha, uv_alpha;
  VP8EncIterator it;
  int delta_progress;
} SegmentJob;

// main work call
static int DoSegmentsJob(SegmentJob* const job, VP8EncIterator* const it) {
  int ok = 1;
  if (!VP8IteratorIsDone(it)) {
    uint8_t tmp[32 + ALIGN_CST];
    uint8_t* const scratch = (uint8_t*)DO_ALIGN(tmp);
    do {
      // Let's pretend we have perfect lossless reconstruction.
      VP8IteratorImport(it, scratch);
      MBAnalyze(it, job->alphas, &job->alpha, &job->uv_alpha);
      ok = VP8IteratorProgress(it, job->delta_progress);
    } while (ok && VP8IteratorNext(it));
  }
  return ok;
}

static void MergeJobs(const SegmentJob* const src, SegmentJob* const dst) {
  int i;
  for (i = 0; i <= MAX_ALPHA; ++i) dst->alphas[i] += src->alphas[i];
  dst->alpha += src->alpha;
  dst->uv_alpha += src->uv_alpha;
}

// initialize the job struct with some TODOs
static void InitSegmentJob(VP8Encoder* const enc, SegmentJob* const job,
                           int start_row, int end_row) {
  WebPGetWorkerInterface()->Init(&job->worker);
  job->worker.data1 = job;
  job->worker.data2 = &job->it;
  job->worker.hook = (WebPWorkerHook)DoSegmentsJob;
  VP8IteratorInit(enc, &job->it);
  VP8IteratorSetRow(&job->it, start_row);
  VP8IteratorSetCountDown(&job->it, (end_row - start_row) * enc->mb_w_);
  memset(job->alphas, 0, sizeof(job->alphas));
  job->alpha = 0;
  job->uv_alpha = 0;
  // only one of both jobs can record the progress, since we don't
  // expect the user's hook to be multi-thread safe
  job->delta_progress = (start_row == 0) ? 20 : 0;
}

// main entry point
int VP8EncAnalyze(VP8Encoder* const enc) {
  int ok = 1;
  const int do_segments =
      enc->config_->emulate_jpeg_size ||   // We need the complexity evaluation.
      (enc->segment_hdr_.num_segments_ > 1) ||
      (enc->method_ == 0);  // for method 0, we need preds_[] to be filled.
  if (do_segments) {