This repository hosts code for handling data streams produced by the ffmpeg_image_transport.
Continuous integration is tested under Ubuntu with the following ROS2 distros:
sudo apt-get install ros-${ROS_DISTRO}-ffmpeg-image-transport-toolsSet the following shell variables:
repo=ffmpeg_image_transport_tools
url=https://github.com/ros-misc-utilities/${repo}.gitand follow the instructions here
The bag_to_file merges the ffmpeg-generated packets from a rosbag into a file:
bag_to_file -b input_bag -t topic -r rate [-o out_file] [-T timestamp_file] [-s start_time] [-e end_time]
The rate determines the fps used by ffmpeg when producing the
output. The video is not transcoded, so what you get is the original
stream, just in a mp4 container. To get correct playing speed the rate must
match the rate at which the stream was originally recorded.
The start_time and end_time is given in seconds since the
epoch, like the times you see when using ros2 bag info.
For example the following line produces a file video.mp4 and timestamps.txt from a rosbag:
ros2 run ffmpeg_image_transport_tools bag_to_file -t /cam1/image_raw/ffmpeg -r 40 -b ./my_rosbag/ -e 1710085164.466
The timestamp.txt file has the following entries:
# packet no, pts, header_stamp recording_stamp
0 0 1710085154473057750 1710085156001866724
1 1 1710085155950467594 1710085156024209913
A H264 packet typically corresponds to a frame so the packet number conincides with the frame number.
The bag_to_frames decodes the ffmpeg-generated packets from a rosbag into frames:
bag_to_frames -b input_bag -t topic [-o out_dir] [-d decoder][-T timestamp_file] [-s start_time] [-e end_time]
The frames are written to out_dir with the ros header stamps embedded in the file name. A suitable decoder is usually guessed from the encoding used in the packet, but you can specify a valid ffmpeg decoder by using the -d decoder option. For start and stop times and the timestamp file see bag_to_file.
This software is issued under the Apache License Version 2.0.