# Enable core audio with `qrb_ros_audio_service`
The `qrb_ros_audio_service` sample application is a ROS package that delivers core audio functionalities, serving as the primary interface for audio capabilities (currently supporting playback and recording) within the ROS ecosystem.
Note
For more information, see the [qrb_ros_audio_service](https://github.com/qualcomm-qrb-ros/qrb_ros_audio_service) GitHub repo.
## Pipeline for `qrb_ros_audio_service`
The following figure shows the pipeline.
**Figure : `qrb_ros_audio_service` pipeline**
## ROS nodes/services used in the `qrb_ros_audio_service` pipeline
| ROS node | Description |
| --- | --- |
| `/audio_service` | This node functions as the primary entry point for the `qrb_ros_audio_service`, offering audio playback and recording capabilities through ROS service requests. |
| ROS service | Type | Description |
| --- | --- | --- |
| `/audio_server` | `qrb_ros_audio_service_msgs::srv::AudioRequest` | Allows ROS applications to send service requests for audio playback and recording. |
## ROS topics used in the `qrb_ros_audio_service` pipeline
| ROS topic | Type | Description |
| --- | --- | --- |
| `/qrb_audiodata` | `qrb_ros_audio_common_msgs::msg::AudioData` | Used for streaming audio playback and recording. Publishes the recorded real-time raw audio data, or allows subscription to this node's raw data for playback. You can modify the topic name using the `--topic_name` parameter. Supports using separate topics for playback and recording operations. |
## Prerequisites
You have **Set up the device** according to [Set up the environment for running sample applications](https://docs.qualcomm.com/doc/80-70022-265/topic/quick_start.html#setup-demo-qs).
## Run out-of-the-box `qrb_ros_audio_service`
1. Start three commandline terminals on your device and run the following commands to set up the environment.
ssh root@[ip-addr]
(ssh) export HOME=/home
(ssh) source /usr/bin/ros_setup.sh && source /usr/share/qirp-setup.sh
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2. In the first SSH terminal, run the audio service package using the `ros2 launch` command.
ros2 launch qrb_ros_audio_service audio_service.launch.py
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3. In the second SSH terminal, run `qrb_ros_audio_common`.
ros2 launch qrb_ros_audio_common component.launch.py
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4. Check the default devices for the pipewire.
1. Verify the status of default speaker and handset mic.
wpctl status
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Audio
├─ Devices:
│
├─ Sinks:
│ \* 42. pal sink speaker ll [vol: 1.00]
│ 44. pal sink speaker\_db [vol: 1.00]
│ 46. pal sink headset\_ll [vol: 1.00]
│ 47. pal sink headset\_db [vol: 1.00]
│
├─ Sources:
│ \* 48. pal source handset mic [vol: 1.00]
│ 50. pal source headset mic [vol: 1.00]
2. If the default speaker or handset mic isn't set, use `wpctl set-default ` to set the default device(s).
# Set the default speaker
wpctl set-default 42
# Set the default handset mic
wpctl set-default 48
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5. In the third SSH terminal, run the test cases using either ROS commands or Python scripts according to the following table.
Note
For all step-by-step test cases, `stream_handle` indicates the stream created by the audio service when the command is `create`. After the audio service creates a stream, the command prints the value of `stream_handle` in the third SSH terminal.
>
>
> - For the ROS command, you see the following output:
>
>
>
> >
> >
> > `stream_handle=<***>`
> - For the Python script, you see the following output:
>
>
>
> >
> >
> > `command create success 1 stream_handle <***>.`
>
>
>
> Download the Python script using
>
>
>
> >
> >
> > wget https://raw.githubusercontent.com/qualcomm-qrb-ros/qrb_ros_audio_service/main/tests/audio_service_test.py
> > Copy to clipboard
>
>
> Table : Audio service commands
>
>
> | Case name | Description | ROS command/Python script |
> | --- | --- | --- |
> | One-touch playback | Start playback with a one-touch command. The speaker outputs the audio. Supports the WAV file format. Place the music file on a device path, for example, `/tmp/music.wav`. | Tab ROS command Tab Python script
ros2 service call /audio_server qrb_ros_audio_service_msgs/srv/AudioRequest "{ command: "play", source: "/tmp/music.wav", volume: 100, }" Copy to clipboard
python3 audio_service_test.py --mode='one-touch' --source='/tmp/music.wav' --volume=100`` Copy to clipboard |
> | Step-by-step playback | Start playback with step-by-step commands. The speaker outputs the audio. Supports the WAV file format. | Tab ROS command Tab Python script
ros2 service call /audio_server qrb_ros_audio_service_msgs/srv/AudioRequest "{ command: "release", stream_handle: , }" Copy to clipboard
python3 audio_service_test.py --type='playback' --source='/tmp/music.wav' --volume=100 python3 audio_service_test.py --set-mute --mute=True --stream_handle= python3 audio_service_test.py --set-mute --mute=False --stream_handle= Copy to clipboard |
> | Streaming playback | Create and start a streaming playback. It subscribes to the audio PCM data from the `loopback` topic. Audio data should be filled with `qrb_ros_audio_common_msgs::msg::AudioData`. | Tab ROS command Tab Python script
python3 audio_service_test.py --mode='one-touch' --channels=1 --sample_rate=16000 --sample_format=16 --pub_pcm=True --volume=100 --topic_name='loopback' Copy to clipboard |
> | Step-by-step record | Use the default input device to record with step-by-step commands and write the audio data to the `/tmp/rec.wav` file. | Tab ROS command Tab Python script