Use chrono steady clock for frame timing (#173)

* Use chrono steady_clock for frame timing

* Fix formatting for humble

* Use chrono in png snapshot streamer

* Don't use std::optional

Author: bjsowa

include/web_video_server/image_streamer.hpp

@@ -30,6 +30,7 @@
 
 #pragma once
 
+#include <chrono>
 #include <memory>
 #include <string>
 
@@ -64,7 +65,7 @@ class ImageStreamer
   /**
    * Restreams the last received image frame if older than max_age.
    */
-  virtual void restreamFrame(double max_age) = 0;
+  virtual void restreamFrame(std::chrono::duration<double> max_age) = 0;
 
   std::string getTopic()
   {
@@ -94,8 +95,8 @@ class ImageTransportImageStreamer : public ImageStreamer
 
 protected:
   virtual cv::Mat decodeImage(const sensor_msgs::msg::Image::ConstSharedPtr & msg);
-  virtual void sendImage(const cv::Mat &, const rclcpp::Time & time) = 0;
-  virtual void restreamFrame(double max_age);
+  virtual void sendImage(const cv::Mat &, const std::chrono::steady_clock::time_point & time) = 0;
+  virtual void restreamFrame(std::chrono::duration<double> max_age);
   virtual void initialize(const cv::Mat &);
 
   image_transport::Subscriber image_sub_;
@@ -105,7 +106,7 @@ class ImageTransportImageStreamer : public ImageStreamer
   std::string default_transport_;
   std::string qos_profile_name_;
 
-  rclcpp::Time last_frame;
+  std::chrono::steady_clock::time_point last_frame_;
   cv::Mat output_size_image;
   std::mutex send_mutex_;
 

include/web_video_server/jpeg_streamers.hpp

@@ -52,7 +52,7 @@ class MjpegStreamer : public ImageTransportImageStreamer
   ~MjpegStreamer();
 
 protected:
-  virtual void sendImage(const cv::Mat &, const rclcpp::Time & time);
+  virtual void sendImage(const cv::Mat &, const std::chrono::steady_clock::time_point & time);
 
 private:
   MultipartStream stream_;
@@ -78,7 +78,7 @@ class JpegSnapshotStreamer : public ImageTransportImageStreamer
   ~JpegSnapshotStreamer();
 
 protected:
-  virtual void sendImage(const cv::Mat &, const rclcpp::Time & time);
+  virtual void sendImage(const cv::Mat &, const std::chrono::steady_clock::time_point & time);
 
 private:
   int quality_;

include/web_video_server/libav_streamer.hpp

@@ -42,6 +42,7 @@ extern "C"
 #include <libavutil/imgutils.h>
 }
 
+#include <chrono>
 #include <memory>
 #include <string>
 
@@ -66,7 +67,7 @@ class LibavStreamer : public ImageTransportImageStreamer
 
 protected:
   virtual void initializeEncoder();
-  virtual void sendImage(const cv::Mat &, const rclcpp::Time & time);
+  virtual void sendImage(const cv::Mat &, const std::chrono::steady_clock::time_point & time);
   virtual void initialize(const cv::Mat &);
   AVFormatContext * format_context_;
   const AVCodec * codec_;
@@ -78,8 +79,9 @@ class LibavStreamer : public ImageTransportImageStreamer
 private:
   AVFrame * frame_;
   struct SwsContext * sws_context_;
-  rclcpp::Time first_image_timestamp_;
   std::mutex encode_mutex_;
+  bool first_image_received_;
+  std::chrono::steady_clock::time_point first_image_time_;
 
   std::string format_name_;
   std::string codec_name_;

include/web_video_server/multipart_stream.hpp

@@ -43,34 +43,35 @@ namespace web_video_server
 
 struct PendingFooter
 {
-  rclcpp::Time timestamp;
+  std::chrono::steady_clock::time_point timestamp;
   std::weak_ptr<std::string> contents;
 };
 
 class MultipartStream
 {
 public:
   MultipartStream(
-    std::function<rclcpp::Time()> get_now,
     async_web_server_cpp::HttpConnectionPtr & connection,
     const std::string & boundry = "boundarydonotcross",
     std::size_t max_queue_size = 1);
 
   void sendInitialHeader();
-  void sendPartHeader(const rclcpp::Time & time, const std::string & type, size_t payload_size);
-  void sendPartFooter(const rclcpp::Time & time);
+  void sendPartHeader(
+    const std::chrono::steady_clock::time_point & time, const std::string & type,
+    size_t payload_size);
+  void sendPartFooter(const std::chrono::steady_clock::time_point & time);
   void sendPartAndClear(
-    const rclcpp::Time & time, const std::string & type,
+    const std::chrono::steady_clock::time_point & time, const std::string & type,
     std::vector<unsigned char> & data);
   void sendPart(
-    const rclcpp::Time & time, const std::string & type, const boost::asio::const_buffer & buffer,
+    const std::chrono::steady_clock::time_point & time, const std::string & type,
+    const boost::asio::const_buffer & buffer,
     async_web_server_cpp::HttpConnection::ResourcePtr resource);
 
 private:
   bool isBusy();
 
 private:
-  std::function<rclcpp::Time()> get_now_;
   const std::size_t max_queue_size_;
   async_web_server_cpp::HttpConnectionPtr connection_;
   std::string boundry_;

include/web_video_server/png_streamers.hpp

@@ -51,7 +51,7 @@ class PngStreamer : public ImageTransportImageStreamer
   ~PngStreamer();
 
 protected:
-  virtual void sendImage(const cv::Mat &, const rclcpp::Time & time);
+  virtual void sendImage(const cv::Mat &, const std::chrono::steady_clock::time_point & time);
   virtual cv::Mat decodeImage(const sensor_msgs::msg::Image::ConstSharedPtr & msg);
 
 private:
@@ -78,7 +78,7 @@ class PngSnapshotStreamer : public ImageTransportImageStreamer
   ~PngSnapshotStreamer();
 
 protected:
-  virtual void sendImage(const cv::Mat &, const rclcpp::Time & time);
+  virtual void sendImage(const cv::Mat &, const std::chrono::steady_clock::time_point & time);
   virtual cv::Mat decodeImage(const sensor_msgs::msg::Image::ConstSharedPtr & msg);
 
 private:

include/web_video_server/ros_compressed_streamer.hpp

@@ -51,18 +51,18 @@ class RosCompressedStreamer : public ImageStreamer
     rclcpp::Node::SharedPtr node);
   ~RosCompressedStreamer();
   virtual void start();
-  virtual void restreamFrame(double max_age);
+  virtual void restreamFrame(std::chrono::duration<double> max_age);
 
 protected:
   virtual void sendImage(
     const sensor_msgs::msg::CompressedImage::ConstSharedPtr msg,
-    const rclcpp::Time & time);
+    const std::chrono::steady_clock::time_point & time);
 
 private:
   void imageCallback(const sensor_msgs::msg::CompressedImage::ConstSharedPtr msg);
   MultipartStream stream_;
   rclcpp::Subscription<sensor_msgs::msg::CompressedImage>::SharedPtr image_sub_;
-  rclcpp::Time last_frame;
+  std::chrono::steady_clock::time_point last_frame_;
   sensor_msgs::msg::CompressedImage::ConstSharedPtr last_msg;
   std::mutex send_mutex_;
   std::string qos_profile_name_;

include/web_video_server/web_video_server.hpp

@@ -94,7 +94,7 @@ class WebVideoServer : public rclcpp::Node
     const char * begin, const char * end);
 
 private:
-  void restreamFrames(double max_age);
+  void restreamFrames(std::chrono::duration<double> max_age);
   void cleanup_inactive_streams();
 
   rclcpp::TimerBase::SharedPtr cleanup_timer_;

src/image_streamer.cpp

@@ -110,16 +110,16 @@ void ImageTransportImageStreamer::initialize(const cv::Mat &)
 {
 }
 
-void ImageTransportImageStreamer::restreamFrame(double max_age)
+void ImageTransportImageStreamer::restreamFrame(std::chrono::duration<double> max_age)
 {
   if (inactive_ || !initialized_) {
     return;
   }
   try {
-    if (last_frame + rclcpp::Duration::from_seconds(max_age) < node_->now() ) {
+    if (last_frame_ + max_age < std::chrono::steady_clock::now()) {
       std::scoped_lock lock(send_mutex_);
       // don't update last_frame, it may remain an old value.
-      sendImage(output_size_image, node_->now());
+      sendImage(output_size_image, std::chrono::steady_clock::now());
     }
   } catch (boost::system::system_error & e) {
     // happens when client disconnects
@@ -199,8 +199,8 @@ void ImageTransportImageStreamer::imageCallback(const sensor_msgs::msg::Image::C
       initialized_ = true;
     }
 
-    last_frame = node_->now();
-    sendImage(output_size_image, msg->header.stamp);
+    last_frame_ = std::chrono::steady_clock::now();
+    sendImage(output_size_image, last_frame_);
   } catch (cv_bridge::Exception & e) {
     auto & clk = *node_->get_clock();
     RCLCPP_ERROR_THROTTLE(node_->get_logger(), clk, 40, "cv_bridge exception: %s", e.what());

src/jpeg_streamers.cpp

@@ -38,7 +38,7 @@ MjpegStreamer::MjpegStreamer(
   const async_web_server_cpp::HttpRequest & request,
   async_web_server_cpp::HttpConnectionPtr connection, rclcpp::Node::SharedPtr node)
 : ImageTransportImageStreamer(request, connection, node),
-  stream_(std::bind(&rclcpp::Node::now, node), connection)
+  stream_(connection)
 {
   quality_ = request.get_query_param_value_or_default<int>("quality", 95);
   stream_.sendInitialHeader();
@@ -50,7 +50,9 @@ MjpegStreamer::~MjpegStreamer()
   std::scoped_lock lock(send_mutex_);  // protects sendImage.
 }
 
-void MjpegStreamer::sendImage(const cv::Mat & img, const rclcpp::Time & time)
+void MjpegStreamer::sendImage(
+  const cv::Mat & img,
+  const std::chrono::steady_clock::time_point & time)
 {
   std::vector<int> encode_params;
   encode_params.push_back(cv::IMWRITE_JPEG_QUALITY);
@@ -94,7 +96,9 @@ JpegSnapshotStreamer::~JpegSnapshotStreamer()
   std::scoped_lock lock(send_mutex_);  // protects sendImage.
 }
 
-void JpegSnapshotStreamer::sendImage(const cv::Mat & img, const rclcpp::Time & time)
+void JpegSnapshotStreamer::sendImage(
+  const cv::Mat & img,
+  const std::chrono::steady_clock::time_point & time)
 {
   std::vector<int> encode_params;
   encode_params.push_back(cv::IMWRITE_JPEG_QUALITY);
@@ -104,7 +108,9 @@ void JpegSnapshotStreamer::sendImage(const cv::Mat & img, const rclcpp::Time & t
   cv::imencode(".jpeg", img, encoded_buffer, encode_params);
 
   char stamp[20];
-  snprintf(stamp, sizeof(stamp), "%.06lf", time.seconds());
+  snprintf(
+    stamp, sizeof(stamp), "%.06lf",
+    std::chrono::duration_cast<std::chrono::duration<double>>(time.time_since_epoch()).count());
   async_web_server_cpp::HttpReply::builder(async_web_server_cpp::HttpReply::ok)
   .header("Connection", "close")
   .header("Server", "web_video_server")

src/libav_streamer.cpp

@@ -44,9 +44,9 @@ LibavStreamer::LibavStreamer(
   const std::string & format_name, const std::string & codec_name,
   const std::string & content_type)
 : ImageTransportImageStreamer(request, connection, node), format_context_(0), codec_(0),
-  codec_context_(0), video_stream_(0), frame_(0), sws_context_(0), first_image_timestamp_(0),
-  format_name_(format_name), codec_name_(codec_name), content_type_(content_type), opt_(0),
-  io_buffer_(0)
+  codec_context_(0), video_stream_(0), frame_(0), sws_context_(0),
+  first_image_received_(false), first_image_time_(), format_name_(format_name),
+  codec_name_(codec_name), content_type_(content_type), opt_(0), io_buffer_(0)
 {
   bitrate_ = request.get_query_param_value_or_default<int>("bitrate", 100000);
   qmin_ = request.get_query_param_value_or_default<int>("qmin", 10);
@@ -215,11 +215,14 @@ void LibavStreamer::initializeEncoder()
 {
 }
 
-void LibavStreamer::sendImage(const cv::Mat & img, const rclcpp::Time & time)
+void LibavStreamer::sendImage(
+  const cv::Mat & img,
+  const std::chrono::steady_clock::time_point & time)
 {
   std::scoped_lock lock(encode_mutex_);
-  if (0 == first_image_timestamp_.nanoseconds()) {
-    first_image_timestamp_ = time;
+  if (!first_image_received_) {
+    first_image_received_ = true;
+    first_image_time_ = time;
   }
 
   AVPixelFormat input_coding_format = AV_PIX_FMT_BGR24;
@@ -274,7 +277,8 @@ void LibavStreamer::sendImage(const cv::Mat & img, const rclcpp::Time & time)
     std::size_t size;
     uint8_t * output_buf;
 
-    double seconds = (time - first_image_timestamp_).seconds();
+    double seconds = std::chrono::duration_cast<std::chrono::duration<double>>(
+      time - first_image_time_).count();
     // Encode video at 1/0.95 to minimize delay
     pkt->pts = (int64_t)(seconds / av_q2d(video_stream_->time_base) * 0.95);
     if (pkt->pts <= 0) {