Tutorial: Automatic recording of audio#

🏁 Goal of this tutorial

Write a Python script that subscribes to the /audio/channel0 topic and writes it to a .wav file.

On your development machine, copy-paste the following record.py inside ROS package named e.g. audio_recorder:

#!/usr/bin/env python3
import wave
import rospy
from audio_common_msgs.msg import AudioData


AUDIO_RATE = 16000
AUDIO_CHANNELS = 1
AUDIO_WIDTH = 2


def channel_callback(msg, wf):
    wf.writeframes(msg.data)

if __name__ == '__main__':
    # call the relevant service
    rospy.init_node('record_audio')

    wf = wave.open("test_audio.wav", 'wb') #change output directory as desired
    wf.setnchannels(AUDIO_CHANNELS)
    wf.setsampwidth(AUDIO_WIDTH)
    wf.setframerate(AUDIO_RATE)

    #Record processed audio, corresponding to channel 0
    rospy.Subscriber('/audio/channel0', AudioData, channel_callback, wf)

    print("recording...")
    rospy.spin()
    print("saving...")
    wf.close()

Remember to export the ROS_MASTER_URI of the robot and the ROS_IP of your laptop, and test it:

rosrun audio_recorder record.py

If you wish to run it inside the robot, remember to modify the CMakeList.txt of your ROS package before deploying the code inside the robot and executing the command:

install(
    PROGRAMS
    scripts/record.py
    DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION})

If you want to test it on the robot, it already has it installed, it is enough to execute it with:

ssh pal@<robot>-0c

rosrun respeaker_ros record.py

Speak to the robot, and, to stop recording, press CTRL+C. You can then play the recorded file, note the file is saved from wherever you have executed the recording command.

aplay test_audio.wav

If you have recorded it from the robot, you can then copy it back to your laptop. From your laptop directory:

scp pal@<robot>-0c:/home/pal/test_audio.wav ~/desired_dir_on_my_laptop

Tutorial: Automatic recording of audio#

See also#