libwebp: update to v0.5.1

third_party/libwebp/enc/webpenc.c

 // Copyright 2011 Google Inc. All Rights Reserved.
 //
 // Use of this source code is governed by a BSD-style license
 // that can be found in the COPYING file in the root of the source
 // tree. An additional intellectual property rights grant can be found
 // in the file PATENTS. All contributing project authors may
 // be found in the AUTHORS file in the root of the source tree.
 // -----------------------------------------------------------------------------
 //
 // WebP encoder: main entry point
@@ skipping 87 matching lines @@
   const int limit = 100 - config->partition_limit;
   enc->method_ = method;
   enc->rd_opt_level_ = (method >= 6) ? RD_OPT_TRELLIS_ALL
                      : (method >= 5) ? RD_OPT_TRELLIS
                      : (method >= 3) ? RD_OPT_BASIC
                      : RD_OPT_NONE;
   enc->max_i4_header_bits_ =
       256 * 16 * 16 *                 // upper bound: up to 16bit per 4x4 block
       (limit * limit) / (100 * 100);  // ... modulated with a quadratic curve.
 
+  // partition0 = 512k max.
+  enc->mb_header_limit_ =
+      (score_t)256 * 510 * 8 * 1024 / (enc->mb_w_ * enc->mb_h_);
+
   enc->thread_level_ = config->thread_level;
 
   enc->do_search_ = (config->target_size > 0 || config->target_PSNR > 0);
   if (!config->low_memory) {
 #if !defined(DISABLE_TOKEN_BUFFER)
     enc->use_tokens_ = (enc->rd_opt_level_ >= RD_OPT_BASIC);  // need rd stats
 #endif
     if (enc->use_tokens_) {
       enc->num_parts_ = 1;   // doesn't work with multi-partition
     }
@@ skipping 264 matching lines @@
 
     if (!config->exact) {
       WebPCleanupTransparentAreaLossless(pic);
     }
 
     ok = VP8LEncodeImage(config, pic);  // Sets pic->error in case of problem.
   }
 
   return ok;
 }