Enable QP parsing from CABAC bitstreams

webrtc/common_video/h264/h264_bitstream_parser.cc

 /*
  *  Copyright (c) 2015 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/h264_bitstream_parser.h"
@@ skipping 224 matching lines @@
             RETURN_INV_ON_FAIL(slice_reader.ReadExponentialGolomb(&golomb_tmp));
           }
           if (memory_management_control_operation == 4) {
             // max_long_term_frame_idx_plus1: ue(v)
             RETURN_INV_ON_FAIL(slice_reader.ReadExponentialGolomb(&golomb_tmp));
           }
         } while (memory_management_control_operation != 0);
       }
     }
   }
-  // cabac not supported: entropy_coding_mode_flag == 0 asserted above.
-  // if (entropy_coding_mode_flag && slice_type != I && slice_type != SI)
-  //   cabac_init_idc
+  if (pps_->entropy_coding_mode_flag &&
+      slice_type != H264::SliceType::kI && slice_type != H264::SliceType::kSi) {
+    // cabac_init_idc: ue(v)
+    RETURN_INV_ON_FAIL(slice_reader.ReadExponentialGolomb(&golomb_tmp));
+  }
+
   int32_t last_slice_qp_delta;
   RETURN_INV_ON_FAIL(
       slice_reader.ReadSignedExponentialGolomb(&last_slice_qp_delta));
   last_slice_qp_delta_ = rtc::Optional<int32_t>(last_slice_qp_delta);
   return kOk;
 }
 
 void H264BitstreamParser::ParseSlice(const uint8_t* slice, size_t length) {
   H264::NaluType nalu_type = H264::ParseNaluType(slice[0]);
   switch (nalu_type) {
@@ skipping 28 matching lines @@
 }
 
 bool H264BitstreamParser::GetLastSliceQp(int* qp) const {
   if (!last_slice_qp_delta_ || !pps_)
     return false;
   *qp = 26 + pps_->pic_init_qp_minus26 + *last_slice_qp_delta_;
   return true;
 }
 
 }  // namespace webrtc