libwebp-0.6.0-rc1

third_party/libwebp/enc/analysis_enc.c

Index: third_party/libwebp/enc/analysis_enc.c
diff --git a/third_party/libwebp/enc/analysis.c b/third_party/libwebp/enc/analysis_enc.c
similarity index 92%
rename from third_party/libwebp/enc/analysis.c
rename to third_party/libwebp/enc/analysis_enc.c
index 136c331289092af1e301ff12bbec133577ef201d..dce159b316f1c2d44c6aa42cfb76d364f948252f 100644
--- a/third_party/libwebp/enc/analysis.c
+++ b/third_party/libwebp/enc/analysis_enc.c
@@ -15,8 +15,8 @@
 #include <string.h>
 #include <assert.h>
 
-#include "./vp8enci.h"
-#include "./cost.h"
+#include "./vp8i_enc.h"
+#include "./cost_enc.h"
 #include "../utils/utils.h"
 
 #define MAX_ITERS_K_MEANS  6
@@ -262,6 +262,29 @@ static int MBAnalyzeBestIntra16Mode(VP8EncIterator* const it) {
   return best_alpha;
 }
 
+static int FastMBAnalyze(VP8EncIterator* const it) {
+  // Empirical cut-off value, should be around 16 (~=block size). We use the
+  // [8-17] range and favor intra4 at high quality, intra16 for low quality.
+  const int q = (int)it->enc_->config_->quality;
+  const uint32_t kThreshold = 8 + (17 - 8) * q / 100;
+  int k;
+  uint32_t dc[16], m, m2;
+  for (k = 0; k < 16; k += 4) {
+    VP8Mean16x4(it->yuv_in_ + Y_OFF_ENC + k * BPS, &dc[k]);
+  }
+  for (m = 0, m2 = 0, k = 0; k < 16; ++k) {
+    m += dc[k];
+    m2 += dc[k] * dc[k];
+  }
+  if (kThreshold * m2 < m * m) {
+    VP8SetIntra16Mode(it, 0);   // DC16
+  } else {
+    const uint8_t modes[16] = { 0 };  // DC4
+    VP8SetIntra4Mode(it, modes);
+  }
+  return 0;
+}
+
 static int MBAnalyzeBestIntra4Mode(VP8EncIterator* const it,
                                    int best_alpha) {
   uint8_t modes[16];
@@ -344,13 +367,17 @@ static void MBAnalyze(VP8EncIterator* const it,
   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);
+  if (enc->method_ <= 1) {
+    best_alpha = FastMBAnalyze(it);
+  } else {
+    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);
 
@@ -453,7 +480,7 @@ int VP8EncAnalyze(VP8Encoder* const enc) {
   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.
+      (enc->method_ <= 1);  // for method 0 - 1, we need preds_[] to be filled.
   if (do_segments) {
     const int last_row = enc->mb_h_;
     // We give a little more than a half work to the main thread.