Optimize ParseRbsp method in H264 bitstream parser.

webrtc/common_video/h264/sps_parser.cc

 /*
  *  Copyright (c) 2016 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.
  */
 
 #include "webrtc/common_video/h264/sps_parser.h"
 
 #include <memory>
+#include <vector>
 
 #include "webrtc/common_video/h264/h264_common.h"
 #include "webrtc/base/bitbuffer.h"
-#include "webrtc/base/bytebuffer.h"
 #include "webrtc/base/logging.h"
 
 typedef rtc::Optional<webrtc::SpsParser::SpsState> OptionalSps;
 
 #define RETURN_EMPTY_ON_FAIL(x) \
   if (!(x)) {                   \
     return OptionalSps();       \
   }
 
 namespace webrtc {
 
 // General note: this is based off the 02/2014 version of the H.264 standard.
 // You can find it on this page:
 // http://www.itu.int/rec/T-REC-H.264
 
 // Unpack RBSP and parse SPS state from the supplied buffer.
 rtc::Optional<SpsParser::SpsState> SpsParser::ParseSps(const uint8_t* data,
                                                        size_t length) {
-  std::unique_ptr<rtc::Buffer> unpacked_buffer = H264::ParseRbsp(data, length);
-  rtc::BitBuffer bit_buffer(unpacked_buffer->data(), unpacked_buffer->size());
+  std::vector<uint8_t> unpacked_buffer = H264::ParseRbsp(data, length);
+  rtc::BitBuffer bit_buffer(unpacked_buffer.data(), unpacked_buffer.size());
   return ParseSpsUpToVui(&bit_buffer);
 }
 
 rtc::Optional<SpsParser::SpsState> SpsParser::ParseSpsUpToVui(
     rtc::BitBuffer* buffer) {
   // Now, we need to use a bit buffer to parse through the actual AVC SPS
   // format. See Section 7.3.2.1.1 ("Sequence parameter set data syntax") of the
   // H.264 standard for a complete description.
   // Since we only care about resolution, we ignore the majority of fields, but
   // we still have to actively parse through a lot of the data, since many of
@@ skipping 164 matching lines @@
     }
   }
   // Subtract the crop for each dimension.
   sps.width -= (frame_crop_left_offset + frame_crop_right_offset);
   sps.height -= (frame_crop_top_offset + frame_crop_bottom_offset);
 
   return OptionalSps(sps);
 }
 
 }  // namespace webrtc