Adapt encoder behavior to target bitrate

remoting/codec/webrtc_video_encoder_vpx.cc

Index: remoting/codec/webrtc_video_encoder_vpx.cc
diff --git a/remoting/codec/video_encoder_vpx.cc b/remoting/codec/webrtc_video_encoder_vpx.cc
similarity index 77%
copy from remoting/codec/video_encoder_vpx.cc
copy to remoting/codec/webrtc_video_encoder_vpx.cc
index e281ef58efbc9c9e092c3b2efadf04b528dbebdf..801556b64cd666fc388d4c6949a0a2e96af85618 100644
--- a/remoting/codec/video_encoder_vpx.cc
+++ b/remoting/codec/webrtc_video_encoder_vpx.cc
@@ -1,8 +1,8 @@
-// Copyright 2013 The Chromium Authors. All rights reserved.
+// Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "remoting/codec/video_encoder_vpx.h"
+#include "remoting/codec/webrtc_video_encoder_vpx.h"
 
 #include <utility>
 
@@ -42,11 +42,13 @@ const int kVp9I444ProfileNumber = 1;
 const int kVp9AqModeNone = 0;
 const int kVp9AqModeCyclicRefresh = 3;
 
+const int kDefaultTargetBitrateKbps = 1000;
+
 void SetCommonCodecParameters(vpx_codec_enc_cfg_t* config,
                               const webrtc::DesktopSize& size) {
   // Use millisecond granularity time base.
   config->g_timebase.num = 1;
-  config->g_timebase.den = 1000;
+  config->g_timebase.den = base::Time::kMicrosecondsPerSecond;
 
   config->g_w = size.width();
   config->g_h = size.height();
@@ -61,19 +63,20 @@ void SetCommonCodecParameters(vpx_codec_enc_cfg_t* config,
   config->kf_min_dist = 10000;
   config->kf_max_dist = 10000;
 
-  // Using 2 threads gives a great boost in performance for most systems with
-  // adequate processing power. NB: Going to multiple threads on low end
-  // windows systems can really hurt performance.
-  // http://crbug.com/99179
-  config->g_threads = (base::SysInfo::NumberOfProcessors() > 2) ? 2 : 1;
+  // Allow multiple cores on a system to be used for encoding for
+  // performance while at the same time ensuring we do not saturate.
+  config->g_threads = (base::SysInfo::NumberOfProcessors() + 1) / 2;
+
+  // Do not drop any frames at encoder.
+  config->rc_dropframe_thresh = 0;
+  // We do not want variations in bandwidth.
+  config->rc_end_usage = VPX_CBR;
+  config->rc_undershoot_pct = 100;
+  config->rc_overshoot_pct = 15;
 }
 
 void SetVp8CodecParameters(vpx_codec_enc_cfg_t* config,
                            const webrtc::DesktopSize& size) {
-  // Adjust default target bit-rate to account for actual desktop size.
-  config->rc_target_bitrate = size.width() * size.height() *
-      config->rc_target_bitrate / config->g_w / config->g_h;
-
   SetCommonCodecParameters(config, size);
 
   // Value of 2 means using the real time profile. This is basically a
@@ -81,9 +84,11 @@ void SetVp8CodecParameters(vpx_codec_enc_cfg_t* config,
   // encoding.
   config->g_profile = 2;
 
-  // Clamping the quantizer constrains the worst-case quality and CPU usage.
+  // To enable remoting to be highly interactive and allow the target bitrate
+  // to be met, we relax the max quantizer. The quality will get topped-off
+  // in subsequent frames.
   config->rc_min_quantizer = 20;
-  config->rc_max_quantizer = 30;
+  config->rc_max_quantizer = 63;
 }
 
 void SetVp9CodecParameters(vpx_codec_enc_cfg_t* config,
@@ -139,8 +144,7 @@ void SetVp9CodecOptions(vpx_codec_ctx_t* codec, bool lossless_encode) {
   DCHECK_EQ(VPX_CODEC_OK, ret) << "Failed to set noise sensitivity";
 
   // Configure the codec to tune it for screen media.
-  ret = vpx_codec_control(
-      codec, VP9E_SET_TUNE_CONTENT, VP9E_CONTENT_SCREEN);
+  ret = vpx_codec_control(codec, VP9E_SET_TUNE_CONTENT, VP9E_CONTENT_SCREEN);
   DCHECK_EQ(VPX_CODEC_OK, ret) << "Failed to set screen content mode";
 
   // Set cyclic refresh (aka "top-off") only for lossy encoding.
@@ -205,11 +209,12 @@ void CreateImage(bool use_i444,
   // Assuming macroblocks are 16x16, aligning the planes' strides above also
   // macroblock aligned them.
   static_assert(kMacroBlockSize == 16, "macroblock_size_not_16");
-  const int y_rows = ((image->h - 1) & ~(kMacroBlockSize-1)) + kMacroBlockSize;
+  const int y_rows =
+      ((image->h - 1) & ~(kMacroBlockSize - 1)) + kMacroBlockSize;
   const int uv_rows = y_rows >> image->y_chroma_shift;
 
   // Allocate a YUV buffer large enough for the aligned data & padding.
-  const int buffer_size = y_stride * y_rows + 2*uv_stride * uv_rows;
+  const int buffer_size = y_stride * y_rows + 2 * uv_stride * uv_rows;
   std::unique_ptr<uint8_t[]> image_buffer(new uint8_t[buffer_size]);
 
   // Reset image value to 128 so we just need to fill in the y plane.
@@ -232,22 +237,22 @@ void CreateImage(bool use_i444,
 }  // namespace
 
 // static
-std::unique_ptr<VideoEncoderVpx> VideoEncoderVpx::CreateForVP8() {
-  return base::WrapUnique(new VideoEncoderVpx(false));
+std::unique_ptr<WebRtcVideoEncoderVpx> WebRtcVideoEncoderVpx::CreateForVP8() {
+  return base::WrapUnique(new WebRtcVideoEncoderVpx(false));
 }
 
 // static
-std::unique_ptr<VideoEncoderVpx> VideoEncoderVpx::CreateForVP9() {
-  return base::WrapUnique(new VideoEncoderVpx(true));
+std::unique_ptr<WebRtcVideoEncoderVpx> WebRtcVideoEncoderVpx::CreateForVP9() {
+  return base::WrapUnique(new WebRtcVideoEncoderVpx(true));
 }
 
-VideoEncoderVpx::~VideoEncoderVpx() {}
+WebRtcVideoEncoderVpx::~WebRtcVideoEncoderVpx() {}
 
-void VideoEncoderVpx::SetTickClockForTests(base::TickClock* tick_clock) {
+void WebRtcVideoEncoderVpx::SetTickClockForTests(base::TickClock* tick_clock) {
   clock_ = tick_clock;
 }
 
-void VideoEncoderVpx::SetLosslessEncode(bool want_lossless) {
+void WebRtcVideoEncoderVpx::SetLosslessEncode(bool want_lossless) {
   if (use_vp9_ && (want_lossless != lossless_encode_)) {
     lossless_encode_ = want_lossless;
     if (codec_)
@@ -256,7 +261,7 @@ void VideoEncoderVpx::SetLosslessEncode(bool want_lossless) {
   }
 }
 
-void VideoEncoderVpx::SetLosslessColor(bool want_lossless) {
+void WebRtcVideoEncoderVpx::SetLosslessColor(bool want_lossless) {
   if (use_vp9_ && (want_lossless != lossless_color_)) {
     lossless_color_ = want_lossless;
     // TODO(wez): Switch to ConfigureCodec() path once libvpx supports it.
@@ -268,14 +273,33 @@ void VideoEncoderVpx::SetLosslessColor(bool want_lossless) {
   }
 }
 
-std::unique_ptr<VideoPacket> VideoEncoderVpx::Encode(
+void WebRtcVideoEncoderVpx::UpdateTargetBitrate(int new_bitrate_kbps) {
+  target_bitrate_kbps_ = new_bitrate_kbps;
+  // Configuration not initialized.
+  if (config_.g_timebase.den == 0)
+    return;
+
+  if (config_.rc_target_bitrate == static_cast<unsigned int>(new_bitrate_kbps))
+    return;
+  config_.rc_target_bitrate = new_bitrate_kbps;
+
+  // Update encoder context.
+  if (vpx_codec_enc_config_set(codec_.get(), &config_))
+    NOTREACHED() << "Unable to set encoder config";
+
+  VLOG(1) << "New rc_target_bitrate: " << new_bitrate_kbps << " kbps";
+}
+
+std::unique_ptr<VideoPacket> WebRtcVideoEncoderVpx::Encode(
     const webrtc::DesktopFrame& frame,
     uint32_t flags) {
   DCHECK_LE(32, frame.size().width());
   DCHECK_LE(32, frame.size().height());
 
-  // If there is nothing to encode, and nothing to top-off, then return nothing.
-  if (frame.updated_region().is_empty() && !encode_unchanged_frame_)
+  // VP8: Encode top-off is controlled at the call site.
+  // VP9: Based on information fetching active map, we return here if there is
+  // nothing to top-off.
+  if (use_vp9_ && frame.updated_region().is_empty() && !encode_unchanged_frame_)
     return nullptr;
 
   // Create or reconfigure the codec to match the size of |frame|.
@@ -285,29 +309,32 @@ std::unique_ptr<VideoPacket> VideoEncoderVpx::Encode(
     Configure(frame.size());
   }
 
-  // Convert the updated capture data ready for encode.
-  webrtc::DesktopRegion updated_region;
-  PrepareImage(frame, &updated_region);
-
-  // Update active map based on updated region.
-  SetActiveMapFromRegion(updated_region);
-
-  // Apply active map to the encoder.
   vpx_active_map_t act_map;
   act_map.rows = active_map_size_.height();
   act_map.cols = active_map_size_.width();
   act_map.active_map = active_map_.get();
-  if (vpx_codec_control(codec_.get(), VP8E_SET_ACTIVEMAP, &act_map)) {
-    LOG(ERROR) << "Unable to apply active map";
-  }
 
-  if (flags & REQUEST_KEY_FRAME)
-    vpx_codec_control(codec_.get(), VP8E_SET_FRAME_FLAGS, VPX_EFLAG_FORCE_KF);
+  webrtc::DesktopRegion updated_region;
+  if (!frame.updated_region().is_empty()) {
+    // Convert the updated capture data ready for encode.
+    PrepareImage(frame, &updated_region);
+
+    // Update active map based on updated region.
+    SetActiveMapFromRegion(updated_region);
 
-  // Do the actual encoding.
-  int timestamp = (clock_->NowTicks() - timestamp_base_).InMilliseconds();
+    // Apply active map to the encoder.
+
+    if (vpx_codec_control(codec_.get(), VP8E_SET_ACTIVEMAP, &act_map)) {
+      LOG(ERROR) << "Unable to apply active map";
+    }
+  }
+
+  // Frame rate is adapted based on how well the encoder meets the target
+  // bandwidth requirement. We specify a target rate of 1 / 15 fps here.
+  // TODO(isheriff): Investigate if it makes sense to increase the target FPS.
   vpx_codec_err_t ret = vpx_codec_encode(
-      codec_.get(), image_.get(), timestamp, 1, 0, VPX_DL_REALTIME);
+      codec_.get(), image_.get(), 0, 66666,
+      (flags & REQUEST_KEY_FRAME) ? VPX_EFLAG_FORCE_KF : 0, VPX_DL_REALTIME);
   DCHECK_EQ(ret, VPX_CODEC_OK)
       << "Encoding error: " << vpx_codec_err_to_string(ret) << "\n"
       << "Details: " << vpx_codec_error(codec_.get()) << "\n"
@@ -316,8 +343,8 @@ std::unique_ptr<VideoPacket> VideoEncoderVpx::Encode(
   if (use_vp9_ && !lossless_encode_) {
     ret = vpx_codec_control(codec_.get(), VP9E_GET_ACTIVEMAP, &act_map);
     DCHECK_EQ(ret, VPX_CODEC_OK)
-        << "Failed to fetch active map: "
-        << vpx_codec_err_to_string(ret) << "\n";
+        << "Failed to fetch active map: " << vpx_codec_err_to_string(ret)
+        << "\n";
     UpdateRegionFromActiveMap(&updated_region);
 
     // If the encoder output no changes then there's nothing left to top-off.
@@ -340,11 +367,16 @@ std::unique_ptr<VideoPacket> VideoEncoderVpx::Encode(
     if (!vpx_packet)
       continue;
 
+    int quantizer = -1;
     switch (vpx_packet->kind) {
       case VPX_CODEC_CX_FRAME_PKT:
         got_data = true;
         packet->set_data(vpx_packet->data.frame.buf, vpx_packet->data.frame.sz);
         packet->set_key_frame(vpx_packet->data.frame.flags & VPX_FRAME_IS_KEY);
+        CHECK_EQ(vpx_codec_control(codec_.get(), VP8E_GET_LAST_QUANTIZER_64,
+                                   &quantizer),
+                 VPX_CODEC_OK);
+        packet->set_quantizer(quantizer);
         break;
       default:
         break;
@@ -354,12 +386,16 @@ std::unique_ptr<VideoPacket> VideoEncoderVpx::Encode(
   return packet;
 }
 
-VideoEncoderVpx::VideoEncoderVpx(bool use_vp9)
+WebRtcVideoEncoderVpx::WebRtcVideoEncoderVpx(bool use_vp9)
     : use_vp9_(use_vp9),
+      target_bitrate_kbps_(kDefaultTargetBitrateKbps),
       encode_unchanged_frame_(false),
-      clock_(&default_tick_clock_) {}
+      clock_(&default_tick_clock_) {
+  // Indicates config is still uninitialized.
+  config_.g_timebase.den = 0;
+}
 
-void VideoEncoderVpx::Configure(const webrtc::DesktopSize& size) {
+void WebRtcVideoEncoderVpx::Configure(const webrtc::DesktopSize& size) {
   DCHECK(use_vp9_ || !lossless_color_);
   DCHECK(use_vp9_ || !lossless_encode_);
 
@@ -385,32 +421,27 @@ void VideoEncoderVpx::Configure(const webrtc::DesktopSize& size) {
     }
   }
 
-  // (Re)Set the base for frame timestamps if the codec is being (re)created.
-  if (!codec_) {
-    timestamp_base_ = clock_->NowTicks();
-  }
-
   // Fetch a default configuration for the desired codec.
   const vpx_codec_iface_t* interface =
       use_vp9_ ? vpx_codec_vp9_cx() : vpx_codec_vp8_cx();
-  vpx_codec_enc_cfg_t config;
-  vpx_codec_err_t ret = vpx_codec_enc_config_default(interface, &config, 0);
+  vpx_codec_err_t ret = vpx_codec_enc_config_default(interface, &config_, 0);
   DCHECK_EQ(VPX_CODEC_OK, ret) << "Failed to fetch default configuration";
 
   // Customize the default configuration to our needs.
   if (use_vp9_) {
-    SetVp9CodecParameters(&config, size, lossless_color_, lossless_encode_);
+    SetVp9CodecParameters(&config_, size, lossless_color_, lossless_encode_);
   } else {
-    SetVp8CodecParameters(&config, size);
+    SetVp8CodecParameters(&config_, size);
   }
+  config_.rc_target_bitrate = target_bitrate_kbps_;
 
   // Initialize or re-configure the codec with the custom configuration.
   if (!codec_) {
     codec_.reset(new vpx_codec_ctx_t);
-    ret = vpx_codec_enc_init(codec_.get(), interface, &config, 0);
+    ret = vpx_codec_enc_init(codec_.get(), interface, &config_, 0);
     CHECK_EQ(VPX_CODEC_OK, ret) << "Failed to initialize codec";
   } else {
-    ret = vpx_codec_enc_config_set(codec_.get(), &config);
+    ret = vpx_codec_enc_config_set(codec_.get(), &config_);
     CHECK_EQ(VPX_CODEC_OK, ret) << "Failed to reconfigure codec";
   }
 
@@ -422,8 +453,9 @@ void VideoEncoderVpx::Configure(const webrtc::DesktopSize& size) {
   }
 }
 
-void VideoEncoderVpx::PrepareImage(const webrtc::DesktopFrame& frame,
-                                   webrtc::DesktopRegion* updated_region) {
+void WebRtcVideoEncoderVpx::PrepareImage(
+    const webrtc::DesktopFrame& frame,
+    webrtc::DesktopRegion* updated_region) {
   if (frame.updated_region().is_empty()) {
     updated_region->Clear();
     return;
@@ -474,13 +506,12 @@ void VideoEncoderVpx::PrepareImage(const webrtc::DesktopFrame& frame,
       for (webrtc::DesktopRegion::Iterator r(*updated_region); !r.IsAtEnd();
            r.Advance()) {
         const webrtc::DesktopRect& rect = r.rect();
-        int rgb_offset = rgb_stride * rect.top() +
-                         rect.left() * kBytesPerRgbPixel;
+        int rgb_offset =
+            rgb_stride * rect.top() + rect.left() * kBytesPerRgbPixel;
         int yuv_offset = uv_stride * rect.top() + rect.left();
         libyuv::ARGBToI444(rgb_data + rgb_offset, rgb_stride,
-                           y_data + yuv_offset, y_stride,
-                           u_data + yuv_offset, uv_stride,
-                           v_data + yuv_offset, uv_stride,
+                           y_data + yuv_offset, y_stride, u_data + yuv_offset,
+                           uv_stride, v_data + yuv_offset, uv_stride,
                            rect.width(), rect.height());
       }
       break;
@@ -488,15 +519,14 @@ void VideoEncoderVpx::PrepareImage(const webrtc::DesktopFrame& frame,
       for (webrtc::DesktopRegion::Iterator r(*updated_region); !r.IsAtEnd();
            r.Advance()) {
         const webrtc::DesktopRect& rect = r.rect();
-        int rgb_offset = rgb_stride * rect.top() +
-                         rect.left() * kBytesPerRgbPixel;
+        int rgb_offset =
+            rgb_stride * rect.top() + rect.left() * kBytesPerRgbPixel;
         int y_offset = y_stride * rect.top() + rect.left();
         int uv_offset = uv_stride * rect.top() / 2 + rect.left() / 2;
-        libyuv::ARGBToI420(rgb_data + rgb_offset, rgb_stride,
-                           y_data + y_offset, y_stride,
-                           u_data + uv_offset, uv_stride,
-                           v_data + uv_offset, uv_stride,
-                           rect.width(), rect.height());
+        libyuv::ARGBToI420(rgb_data + rgb_offset, rgb_stride, y_data + y_offset,
+                           y_stride, u_data + uv_offset, uv_stride,
+                           v_data + uv_offset, uv_stride, rect.width(),
+                           rect.height());
       }
       break;
     default:
@@ -505,7 +535,7 @@ void VideoEncoderVpx::PrepareImage(const webrtc::DesktopFrame& frame,
   }
 }
 
-void VideoEncoderVpx::SetActiveMapFromRegion(
+void WebRtcVideoEncoderVpx::SetActiveMapFromRegion(
     const webrtc::DesktopRegion& updated_region) {
   // Clear active map first.
   memset(active_map_.get(), 0,
@@ -531,7 +561,7 @@ void VideoEncoderVpx::SetActiveMapFromRegion(
   }
 }
 
-void VideoEncoderVpx::UpdateRegionFromActiveMap(
+void WebRtcVideoEncoderVpx::UpdateRegionFromActiveMap(
     webrtc::DesktopRegion* updated_region) {
   const uint8_t* map = active_map_.get();
   for (int y = 0; y < active_map_size_.height(); ++y) {