Log audio network adapter decisions in event log.

webrtc/modules/audio_coding/audio_network_adaptor/event_log_writer.h

Index: webrtc/modules/audio_coding/audio_network_adaptor/event_log_writer.h
diff --git a/webrtc/modules/audio_coding/audio_network_adaptor/event_log_writer.h b/webrtc/modules/audio_coding/audio_network_adaptor/event_log_writer.h
new file mode 100644
index 0000000000000000000000000000000000000000..d3aadbd40ef800f990876c3a8f5ccd7e4fc93437
--- /dev/null
+++ b/webrtc/modules/audio_coding/audio_network_adaptor/event_log_writer.h
@@ -0,0 +1,40 @@
+/*
+ *  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.
+ */
+
+#ifndef WEBRTC_MODULES_AUDIO_CODING_AUDIO_NETWORK_ADAPTOR_EVENT_LOG_WRITER_H_
+#define WEBRTC_MODULES_AUDIO_CODING_AUDIO_NETWORK_ADAPTOR_EVENT_LOG_WRITER_H_
+
+#include "webrtc/base/constructormagic.h"
+#include "webrtc/modules/audio_coding/audio_network_adaptor/include/audio_network_adaptor.h"
+
+namespace webrtc {
+class RtcEventLog;
+
+class EventLogWriter {
+ public:
+  EventLogWriter(RtcEventLog* event_log,
+                 int min_bitreate_change_bps,
+                 float min_packet_loss_change_fraction);
+  explicit EventLogWriter(RtcEventLog* event_log);
+  ~EventLogWriter();
+  void MayLogEncoderRuntimeConfig(
+      const AudioNetworkAdaptor::EncoderRuntimeConfig& config);
+
+ private:
+  RtcEventLog* event_log_;
+  rtc::Optional<AudioNetworkAdaptor::EncoderRuntimeConfig> last_runtime_config_;
+  const int min_bitreate_change_bps_;

[minyue-webrtc, 2016/12/12 10:33:12]

bitrate

and do we want to make it a ratio?

5 -> 10 is considered a large change while 35 -> 40 may not?

[michaelt, 2016/12/12 10:50:08]

My original idea was to use a ratio value for bit-rate and packet loss.
But after some deeper thoughts about this, i decided to use no ratio for the
bitrate.
I agree that the changes of in small rates may be more imported, but since the
bitrate is not a precises representation of BW it seams not very useful to me to
log more on lower bit-rates. 

+  const float min_packet_loss_change_fraction_;

[minyue-webrtc, 2016/12/12 10:33:12]

also a ratio?

[michaelt, 2016/12/12 10:50:08]

This is a ratio all already.
I may could change the name of the variable.

+  RTC_DISALLOW_COPY_AND_ASSIGN(EventLogWriter);
+};
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_MODULES_AUDIO_CODING_AUDIO_NETWORK_ADAPTOR_EVENT_LOG_WRITER_H_