Always copy processed audio to output buffer in ProcessStream.

In the old AudioFrame ProcessStream API, input and output buffers were shared.
Now that the buffers are distinct, the input must be copied to the
output even when no processing occurred.

R=andrew@webrtc.org

Committed: https://code.google.com/p/webrtc/source/detail?r=78de5010d167d1e375e05d26177aad43c2e2de08

Review URL: https://webrtc-codereview.appspot.com/41459004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@8052 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/modules/audio_processing/audio_processing_impl.cc

@@ -498,11 +498,9 @@ int AudioProcessingImpl::ProcessStream(const float* const* src,
 
   capture_audio_->CopyFrom(src, samples_per_channel, input_layout);
   RETURN_ON_ERR(ProcessStreamLocked());
-  if (output_copy_needed(is_data_processed())) {
-    capture_audio_->CopyTo(fwd_out_format_.samples_per_channel(),
-                           output_layout,
-                           dest);
-  }
+  capture_audio_->CopyTo(fwd_out_format_.samples_per_channel(),
+                         output_layout,
+                         dest);
 
 #ifdef WEBRTC_AUDIOPROC_DEBUG_DUMP
   if (debug_file_->Open()) {

webrtc/modules/audio_processing/test/audio_processing_unittest.cc

@@ -1344,6 +1344,28 @@ TEST_F(ApmTest, NoProcessingWhenAllComponentsDisabled) {
   }
 }
 
+TEST_F(ApmTest, NoProcessingWhenAllComponentsDisabledFloat) {
+  // Test that ProcessStream copies input to output even with no processing.
+  const size_t kSamples = 80;
+  const int sample_rate = 8000;
+  const float src[kSamples] = {
+    -1.0f, 0.0f, 1.0f
+  };
+  float dest[kSamples] = {};
+
+  auto src_channels = &src[0];
+  auto dest_channels = &dest[0];
+
+  apm_.reset(AudioProcessing::Create());
+  EXPECT_NOERR(apm_->ProcessStream(
+      &src_channels, kSamples, sample_rate, LayoutFromChannels(1),
+      sample_rate, LayoutFromChannels(1), &dest_channels));
+
+  for (size_t i = 0; i < kSamples; ++i) {
+    EXPECT_EQ(src[i], dest[i]);
+  }
+}
+
 TEST_F(ApmTest, IdenticalInputChannelsResultInIdenticalOutputChannels) {
   EnableAllComponents();