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add a -jpeg_like option

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This option remaps internal parameters to better match
the expected compression curve of JPEG and produce output files
of similar size, but with better quality.

Change-Id: I96a1cbb480b1f6a0c6845a23c33dfd63f197b689
This commit is contained in:
skal
2013-02-05 19:40:18 +01:00
parent 1f803f645d
commit e895059a05
8 changed files with 80 additions and 29 deletions
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37
src/enc/analysis.c
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@ -318,7 +318,8 @@ static int MBAnalyzeBestUVMode(VP8EncIterator* const it) {
}
static void MBAnalyze(VP8EncIterator* const it,
int alphas[MAX_ALPHA + 1], int* const uv_alpha) {
int alphas[MAX_ALPHA + 1],
int* const alpha, int* const uv_alpha) {
const VP8Encoder* const enc = it->enc_;
int best_alpha, best_uv_alpha;
@ -340,8 +341,11 @@ static void MBAnalyze(VP8EncIterator* const it,
best_alpha = (3 * best_alpha + best_uv_alpha + 2) >> 2;
best_alpha = FinalAlphaValue(best_alpha);
alphas[best_alpha]++;
*uv_alpha += best_uv_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) {
@ -362,35 +366,42 @@ static void DefaultMBInfo(VP8MBInfo* const mb) {
// 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_.
WebPReportProgress(enc->pic_, enc->percent_ + 20, &enc->percent_);
}
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_ <= 2); // for methods 0,1,2, we need preds_[] to be filled.
enc->alpha_ = 0;
enc->uv_alpha_ = 0;
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_);
MBAnalyze(&it, alphas, &enc->alpha_, &enc->uv_alpha_);
ok = VP8IteratorProgress(&it, 20);
// Let's pretend we have perfect lossless reconstruction.
} while (ok && VP8IteratorNext(&it, it.yuv_in_));
enc->alpha_ /= enc->mb_w_ * enc->mb_h_;
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_);
ResetAllMBInfo(enc);
}
return ok;
}