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[video_recorder] Add timer to record low fps video at the correct speed #600

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[video_recorder] Add timer to record low fps video at the correct speed #600

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2c675f5
[video_recorder] Add timer to record low fps video at the correct speed
708yamaguchi Sep 18, 2020
d6b8e62
Remove trailing whitespace
708yamaguchi Sep 18, 2020
0acb251
Use ros::Time::now() for the last image writing
708yamaguchi Oct 9, 2020
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28 changes: 18 additions & 10 deletions image_view/src/nodes/video_recorder.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -39,6 +39,8 @@ double min_depth_range;
double max_depth_range;
bool use_dynamic_range;
int colormap;
cv::Mat image;
ros::Time stamp;


void callback(const sensor_msgs::ImageConstPtr& image_msg)
Expand Down Expand Up @@ -70,7 +72,8 @@ void callback(const sensor_msgs::ImageConstPtr& image_msg)

}

if ((image_msg->header.stamp - g_last_wrote_time) < ros::Duration(1.0 / fps))
stamp = image_msg->header.stamp;
if ((stamp - g_last_wrote_time) < ros::Duration(1.0 / fps))
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@JWhitleyWork JWhitleyWork Oct 8, 2020

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This change is unnecessary given my other comment.

{
// Skip to get video with correct fps
return;
Expand All @@ -83,22 +86,26 @@ void callback(const sensor_msgs::ImageConstPtr& image_msg)
options.min_image_value = min_depth_range;
options.max_image_value = max_depth_range;
options.colormap = colormap;
const cv::Mat image = cv_bridge::cvtColorForDisplay(cv_bridge::toCvShare(image_msg), encoding, options)->image;
if (!image.empty()) {
outputVideo << image;
ROS_INFO_STREAM("Recording frame " << g_count << "\x1b[1F");
g_count++;
g_last_wrote_time = image_msg->header.stamp;
} else {
ROS_WARN("Frame skipped, no data!");
}
image = cv_bridge::cvtColorForDisplay(cv_bridge::toCvShare(image_msg), encoding, options)->image;
} catch(cv_bridge::Exception)
{
ROS_ERROR("Unable to convert %s image to %s", image_msg->encoding.c_str(), encoding.c_str());
return;
}
}

void timercallback(const ros::TimerEvent&)
{
if (!image.empty()) {
outputVideo << image;
ROS_INFO_STREAM("Recording frame " << g_count << "\x1b[1F");
g_count++;
g_last_wrote_time = stamp;
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@JWhitleyWork JWhitleyWork Oct 8, 2020

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This is no longer true. The timestamp of the last-received image can no longer be considered close enough to the actual time that the frame was written. Use ros::Time::now() instead.

} else {
ROS_WARN("Frame skipped, no data!");
}
}

int main(int argc, char** argv)
{
ros::init(argc, argv, "video_recorder", ros::init_options::AnonymousName);
Expand Down Expand Up @@ -134,6 +141,7 @@ int main(int argc, char** argv)
image_transport::ImageTransport it(nh);
std::string topic = nh.resolveName("image");
image_transport::Subscriber sub_image = it.subscribe(topic, 1, callback);
ros::Timer timer = nh.createTimer(ros::Duration(1.0 / fps), timercallback);

ROS_INFO_STREAM("Waiting for topic " << topic << "...");
ros::spin();
Expand Down