Reduce the runtime of some ACM tests in modules_tests

webrtc/modules/audio_coding/test/iSACTest.cc

 /*
  *  Copyright (c) 2012 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 99 matching lines @@
   EXPECT_EQ(0, _acmB->RegisterTransportCallback(_channel_B2A.get()));
   _channel_B2A->RegisterReceiverACM(_acmA.get());
 
   file_name_swb_ = webrtc::test::ResourcePath("audio_coding/testfile32kHz",
                                               "pcm");
 
   EXPECT_EQ(0, _acmB->RegisterSendCodec(_paramISAC16kHz));
   EXPECT_EQ(0, _acmA->RegisterSendCodec(_paramISAC32kHz));
 
   _inFileA.Open(file_name_swb_, 32000, "rb");
+  // Set test length to 500 ms (50 blocks of 10 ms each).
+  _inFileA.SetNum10MsBlocksToRead(50);
+  // Fast-forward 1 second (100 blocks) since the files start with silence.
+  _inFileA.FastForward(100);
   std::string fileNameA = webrtc::test::OutputPath() + "testisac_a.pcm";
   std::string fileNameB = webrtc::test::OutputPath() + "testisac_b.pcm";
   _outFileA.Open(fileNameA, 32000, "wb");
   _outFileB.Open(fileNameB, 32000, "wb");
 
   while (!_inFileA.EndOfFile()) {
     Run10ms();
   }
   CodecInst receiveCodec;
   EXPECT_EQ(0, _acmA->ReceiveCodec(&receiveCodec));
@@ skipping 200 matching lines @@
       numSendCodecChanged++;
     }
   }
   _outFileA.Close();
   _outFileB.Close();
   _inFileA.Close();
   _inFileB.Close();
 }
 
 }  // namespace webrtc