Fix bug where min transmit bitrate wasn't working

webrtc/video/video_send_stream_tests.cc

 /*
  *  Copyright (c) 2013 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 <algorithm>  // max
@@ skipping 1103 matching lines @@
 
     std::unique_ptr<RtpRtcp> rtp_rtcp_;
     std::unique_ptr<internal::TransportAdapter> feedback_transport_;
     VideoSendStream* stream_;
     bool bitrate_capped_;
   } test;
 
   RunBaseTest(&test);
 }
 
+class MinTransmitBitrateTest : public test::SendTest, public test::FakeEncoder {

[perkj_webrtc, 2016/07/04 14:51:12]

name MaxPaddingSetTest? 

[sprang_webrtc, 2016/07/05 11:29:31]

Done.

+ public:
+  static const uint32_t kMinTransmitBitrateBps = 400000;
+  static const uint32_t kActualEncodeBitrateBps = 40000;
+  static const uint32_t kMinFramesToSend = 10;
+
+  explicit MinTransmitBitrateTest(bool test_switch_content_type)
+      : SendTest(test::CallTest::kDefaultTimeoutMs),
+        FakeEncoder(Clock::GetRealTimeClock()),
+        call_(nullptr),
+        send_stream_(nullptr),
+        frames_sent_(0),
+        running_without_padding_(test_switch_content_type) {}
+
+  void OnVideoStreamsCreated(
+      VideoSendStream* send_stream,
+      const std::vector<VideoReceiveStream*>& receive_streams) override {
+    send_stream_ = send_stream;
+  }
+
+  void ModifyVideoConfigs(
+      VideoSendStream::Config* send_config,
+      std::vector<VideoReceiveStream::Config>* receive_configs,
+      VideoEncoderConfig* encoder_config) override {
+    send_config->encoder_settings.encoder = this;
+    RTC_DCHECK_EQ(1u, encoder_config->streams.size());
+    encoder_config->streams[0].target_bitrate_bps = kMinTransmitBitrateBps * 2;

[perkj_webrtc, 2016/07/04 14:51:12]

are all these modifications really needed?

[sprang_webrtc, 2016/07/05 11:29:31]

Nope. Removed most.

+    encoder_config->streams[0].max_bitrate_bps = kMinTransmitBitrateBps * 4;
+    if (running_without_padding_) {
+      encoder_config->min_transmit_bitrate_bps = 0;
+      encoder_config->content_type =
+          VideoEncoderConfig::ContentType::kRealtimeVideo;
+    } else {
+      encoder_config->min_transmit_bitrate_bps = kMinTransmitBitrateBps;
+      encoder_config->content_type = VideoEncoderConfig::ContentType::kScreen;
+    }
+    encoder_config_ = *encoder_config;
+  }
+
+  int32_t SetRates(uint32_t new_target_bitrate, uint32_t framerate) override {

[perkj_webrtc, 2016/07/04 14:51:12]

not needed any more? 

[sprang_webrtc, 2016/07/05 11:29:31]

Done.

+    // Make sure not to trigger on any default zero bitrates.
+    if (new_target_bitrate == 0)
+      return 0;
+    rtc::CritScope lock(&crit_);
+    return FakeEncoder::SetRates(
+        std::min<uint32_t>(new_target_bitrate, kActualEncodeBitrateBps / 1000),
+        framerate);
+  }
+
+  int32_t Encode(const VideoFrame& input_image,
+                 const CodecSpecificInfo* codec_specific_info,
+                 const std::vector<FrameType>* frame_types) override {
+    int32_t res =
+        FakeEncoder::Encode(input_image, codec_specific_info, frame_types);
+    CheckDoneState();
+    return res;
+  }
+
+  void OnCallsCreated(Call* sender_call, Call* receiver_call) override {
+    call_ = sender_call;
+  }
+
+  void CheckDoneState() {
+    rtc::CritScope lock(&crit_);
+
+    if (running_without_padding_)
+      EXPECT_EQ(0, call_->GetStats().min_transmit_bitrate_bps);

[perkj_webrtc, 2016/07/04 14:51:12]

why not simply call this max_padding_bitrate_bps ? This is not the min transmit
bitrate.

[sprang_webrtc, 2016/07/05 11:29:31]

As discussed offline, yes and no. :)
Changed anyhow.

+
+    // Wait until at least kMinFramesToSend frames have been encoded, so that
+    // we have reliable data.
+    if (++frames_sent_ < kMinFramesToSend)

[perkj_webrtc, 2016/07/04 14:51:12]

nit frames_encoded_ ?

[sprang_webrtc, 2016/07/05 11:29:31]

Acknowledged.

+      return;
+
+    if (running_without_padding_) {
+      // We've sent kMinFramesToSend frames with default configuration, switch
+      // to enabling screen content and setting min transmit bitrate.
+      frames_sent_ = 0;
+      encoder_config_.min_transmit_bitrate_bps = kMinTransmitBitrateBps;
+      encoder_config_.content_type = VideoEncoderConfig::ContentType::kScreen;
+      send_stream_->ReconfigureVideoEncoder(encoder_config_);
+      running_without_padding_ = false;
+      return;
+    }
+
+    // Make sure the pacer has been configured with a min transmit bitrate.
+    if (call_->GetStats().min_transmit_bitrate_bps > 0)
+      observation_complete_.Set();
+  }
+
+  void PerformTest() override {
+    ASSERT_TRUE(Wait()) << "Timed out waiting for a valid padding bitrate.";
+  }
+
+ private:
+  rtc::CriticalSection crit_;
+  Call* call_;
+  VideoSendStream* send_stream_;
+  VideoEncoderConfig encoder_config_;
+  uint32_t frames_sent_ GUARDED_BY(crit_);
+  bool running_without_padding_;
+};
+
+TEST_F(VideoSendStreamTest, RespectsMinTransmitBitrate) {
+  MinTransmitBitrateTest test(false);
+  RunBaseTest(&test);
+}
+
+TEST_F(VideoSendStreamTest, RespectsMinTransmitBitrateAfterContentSwitch) {
+  MinTransmitBitrateTest test(true);
+  RunBaseTest(&test);
+}
+
 TEST_F(VideoSendStreamTest, CanReconfigureToUseStartBitrateAbovePreviousMax) {
   class StartBitrateObserver : public test::FakeEncoder {
    public:
     StartBitrateObserver()
         : FakeEncoder(Clock::GetRealTimeClock()),
           start_bitrate_changed_(false, false),
           start_bitrate_kbps_(0) {}
     int32_t InitEncode(const VideoCodec* config,
                        int32_t number_of_cores,
                        size_t max_payload_size) override {
@@ skipping 1242 matching lines @@
         observation_complete_.Set();
       }
     }
   } test;
 
   RunBaseTest(&test);
 }
 #endif  // !defined(RTC_DISABLE_VP9)
 
 }  // namespace webrtc