Compensate for the IntelligibilityEnhancer processing delay in high bands

webrtc/common_audio/blocker.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 193 matching lines @@
               0,
               block_size_,
               num_output_channels_,
               output_buffer_.channels(),
               first_frame_in_block);
 
     first_frame_in_block += shift_amount_;
   }
 
   // Copy output buffer to output
-  CopyFrames(output_buffer_.channels(),
-             0,
-             chunk_size_,
-             num_output_channels_,
-             output,
-             0);
+  if (output != nullptr) {
+    CopyFrames(output_buffer_.channels(), 0, chunk_size_, num_output_channels_,
+               output, 0);
+  }
 
   // Copy output buffer [chunk_size_, chunk_size_ + initial_delay]
   // to output buffer [0, initial_delay], zero the rest.
   MoveFrames(output_buffer_.channels(),
              chunk_size,
              initial_delay_,
              num_output_channels_,
              output_buffer_.channels(),
              0);
   ZeroOut(output_buffer_.channels(),
           initial_delay_,
           chunk_size_,
           num_output_channels_);
 
   // Calculate new starting frames.
   frame_offset_ = first_frame_in_block - chunk_size_;
 }
 
 }  // namespace webrtc