# h264_video_encoder


## Overview
This package provides a ROS Node that will encode a stream of images into an H264 video stream.

**Keywords**: ROS, AWS, Kinesis

### License
The source code is released under [LGPL 2.1]. However, this package uses `h264_encoder_core` which incorporates several different encoding components which may further restrict the license. By default, x264 is used for software encoding, thereby applying GPL to all of h264_video_encoder.

**Author**: AWS RoboMaker<br/>
**Affiliation**: [Amazon Web Services (AWS)]<br/>

RoboMaker cloud extensions rely on third-party software licensed under open-source licenses and are provided for demonstration purposes only. Incorporation or use of RoboMaker cloud extensions in connection with your production workloads or commercial product(s) or devices may affect your legal rights or obligations under the applicable open-source licenses. AWS does not provide support for this cloud extension. You are solely responsible for how you configure, deploy, and maintain this cloud extension in your workloads or commercial product(s) or devices.

### Supported ROS Distributions
- Kinetic
- Melodic

## Installation

### Building from Source

To build from source you'll need to create a new workspace, clone and checkout the latest release branch of this repository, install all the dependencies, and compile. If you need the latest development features you can clone from the `master` branch instead of the latest release branch. While we guarantee the release branches are stable, __the `master` should be considered to have an unstable build__ due to ongoing development. 

- Install build tool: please refer to `colcon` [installation guide](https://colcon.readthedocs.io/en/released/user/installation.html)

- Create a ROS workspace and a source directory

        mkdir -p ~/ros-workspace/src

- Clone the package into the source directory . 

        cd ~/ros-workspace/src
        git clone https://github.com/aws-robotics/kinesisvideo-encoder-ros1.git -b release-latest

- Install dependencies

        cd ~/ros-workspace 
        sudo apt-get update && rosdep update
        rosdep install --from-paths src --ignore-src -r -y
        
_Note: If building the master branch instead of a release branch you may need to also checkout and build the master branches of the packages this package depends on._

- Build the packages

        cd ~/ros-workspace && colcon build

- Configure ROS library Path

        source ~/ros-workspace/install/setup.bash


- Build and run the unit tests

        colcon build --packages-select h264_video_encoder --cmake-target tests
        colcon test --packages-select h264_video_encoder h264_encoder_core && colcon test-results --all


### Building on Cloud9 - Cross Compilation

- In RoboMaker's Cloud9, start with an empty workspace and in the Cloud9 console:

       # build docker image
       cd /opt/robomaker/cross-compilation-dockerfile/
       sudo bin/build_image.bash  # this step will take a while

       # create workspace
       mkdir -p ~/environment/robot_ws/src
       cd ~/environment/robot_ws/src
       git clone https://github.com/aws-robotics/kinesisvideo-encoder-common.git
       git clone https://github.com/aws-robotics/kinesisvideo-encoder-ros1.git

       # run docker image
       cd ..
       sudo docker run -v $(pwd):/ws -it ros-cross-compile:armhf

- Now you're inside the cross-compilation docker container

       # build the workspace
       cd ws
       apt update
       rosdep install --from-paths src --ignore-src -r -y  # this step will take a while
       colcon build --build-base armhf_build --install-base armhf_install
       colcon bundle --build-base armhf_build --install-base armhf_install --bundle-base armhf_bundle --apt-sources-list /opt/cross/apt-sources.yaml   # this step will take a while
       exit

- Now you're oustide the cross-compilation docker container

       # for more on copying s3 buckets see: https://docs.aws.amazon.com/cli/latest/reference/s3/cp.html
       aws s3 cp armhf_bundle/output.tar.gz s3://<bucket_name_in_your_robomaker_account>/h264_video_encoder.armhf.tar

## Launch Files
A launch file called `h264_video_encoder.launch` is included in this package. The launch file uses the following arguments:

| Arg Name | Description |
| --------- | ------------ |
| node_name | (optional) The name the H264 encoder node should be launched with. If not provided, the node name will default to `h264_video_encoder` |
| config_file | (optional) A path to a rosparam config file. |

An example launch file called `sample_application.launch` is included in this project that gives an example of how you can include this node in your project and provide it with arguments.


## Usage

### Running the node
To launch the H264 encoder node, you can run the following command:

    roslaunch h264_video_encoder sample_application.launch


## Configuration File and Parameters
An example configuration file called `sample_configuration.yaml` is provided for running the H264 encoder node on a Raspberry Pi based system.
When the parameters are absent in the ROS parameter server, default values are used, thus all parameters are optional. See table below for details.

| Parameter Name | Description | Type |
| ------------- | -----------------------------------------------------------| ------------- |
| queue_size | (optional) The maximum number of incoming and outgoing messages to be queued towards the subscribed and publishing topics. | integer |
| output_width | (optional) The desired width (in pixels) of each frame in the encoded video output. | integer |
| output_height | (optional) The desired height (in pixels) of each frame in the encoded video output. | integer |
| fps_numerator | (optional) The desired frames per second (the numerator portion when expressing FPS as a rational number) for the encoded video output. | integer |
| fps_denominator | (optional) The desired frames per second (the denominator portion when expressing FPS as a rational number) for the encoded video output. | integer |
| bitrate | (optional) The desired bitrate (in bits per second) of the encoded video output. | integer |


## Node Details

#### Published Topics
| Topic Name | Message Type | Description |
| ---------- | ------------ | ----------- |
| *Configurable* (default="video/encoded") | kinesis_video_msgs/KinesisVideoFrame | The node will publish to a topic of a given name. Each message being published contains a chunk of the video stream, usually per video frame. |

#### Subscribed Topics
| Topic Name | Message Type | Description |
| ---------- | ------------ | ----------- |
| *Configurable* (default="/raspicam_node/image") | sensor_msgs/Image | The node will subscribe to a topic of a given name. The data is expected to be a stream of images from a source (such as a Raspberry Pi camera). |

[Amazon Web Services (AWS)]: https://aws.amazon.com/
[LGPL 2.1]: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html
[Issue Tracker]: https://github.com/aws-robotics/kinesisvideo-encoder-ros1/issues
[ROS]: http://www.ros.org