VP9: Enable multi-threading for SVC.

webrtc/modules/video_coding/codecs/vp9/vp9_impl.cc

 /*
  *  Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE 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.
  *
  */
@@ skipping 346 matching lines @@
   }
 
   tl0_pic_idx_ = static_cast<uint8_t>(rand());
 
   return InitAndSetControlSettings(inst);
 }
 
 int VP9EncoderImpl::NumberOfThreads(int width,
                                     int height,
                                     int number_of_cores) {
-  // For the current libvpx library, only 1 thread is supported when SVC is
-  // turned on.
-  if (num_temporal_layers_ > 1 || num_spatial_layers_ > 1) {
-    return 1;
-  }
-
   // Keep the number of encoder threads equal to the possible number of column
   // tiles, which is (1, 2, 4, 8). See comments below for VP9E_SET_TILE_COLUMNS.
   if (width * height >= 1280 * 720 && number_of_cores > 4) {
     return 4;
   } else if (width * height >= 640 * 480 && number_of_cores > 2) {
     return 2;
   } else {
     // 1 thread less than VGA.
     return 1;
   }
@@ skipping 438 matching lines @@
     decoder_ = NULL;
   }
   // Releases buffers from the pool. Any buffers not in use are deleted. Buffers
   // still referenced externally are deleted once fully released, not returning
   // to the pool.
   frame_buffer_pool_.ClearPool();
   inited_ = false;
   return WEBRTC_VIDEO_CODEC_OK;
 }
 }  // namespace webrtc