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Orcasound's orcanode code for live-streaming audio data

The orcanode software repository contains audio tools and scripts for capturing, reformatting, transcoding and uploading audio data at each node of a network. Orcanode live-streaming should work on Intel (amd64) or Raspberry Pi (arm32v7) platforms using any soundcard. The most common hardware used by Orcasound is the Pisound HAT on a Raspberry Pi (3B+ or 4) single-board computer.

There is a base set of tools and a couple of specific projects in the node and mseed directories. The node directory is for new locations streaming within the Orcasound listening network (primary nodes).

The mseed directory has code for converting audio data in the mseed format to the live-streaming audio format used by primary nodes. This conversion code is mainly used for audio data collected by the Ocean Observatories Initiative or OOI network. See the README in the mseed directory for more info. Transcoding from other audio formats should likely go in new directories by encoding scheme, similar to the mseed directory...

You can also gain some bioacoustic context for the project in the orcanode wiki.

Background & motivation

This code was developed for live-streaming from source nodes in the Orcasound hydrophone network (WA, USA). Thus, the repository names begin with "orca"! Our primary motivation is to make it easy for community scientists to listen for whales via the Orcasound web app using their favorite device/OS/browser.

We also aspire to use open source software as much as possible. We rely heavily on FFmpeg. One of our long-term goals is to stream lossless FLAC-encoded audio within DASH segments to a player that works optimally on as many listening devices as possible. For now (2018-2023) we have found the best end-to-end performance across the broadest range of web browsers is acheived by streaming AAC-encoded audio within HLS segments.

Getting Started

These instructions will get you a copy of the project up and running on your local machine for development and testing purposes. See the deployment section (below) for notes on how to deploy the project on a live system like live.orcasound.net.

If you want to set up your hardware to host a hydrophone within the Orcasound network, take a look at how to join Orcasound and our prototype built from a Raspberry Pi with the Pisound ADC HAT.

The general scheme is to acquire audio data from a sound card within a Docker container via ALSA or Jack and FFmpeg, and then stream the audio data with minimal latency to cloud-based storage (as of Oct 2021, we use AWS S3 buckets). Errors/etc are logged to LogDNA via a separate Docker container.

Prerequisites

An ARM or X86 device with a sound card (or other audio input devices) connected to the Internet (via wireless network or ethernet cable) that has Docker-compose installed and an AWS account with some S3 buckets set up.

Installing

Create a base docker image for your architecture by running the script in /base/rpi or /base/amd64 as appropriate. You will need to create a .env file as appropriate for your projects. Common to to all projects are the need for AWS keys

AWSACCESSKEYID=YourAWSaccessKey
AWSSECRETACCESSKEY=YourAWSsecretAccessKey
 
SYSLOG_URL=syslog+tls://syslog-a.logdna.com:YourLogDNAPort
SYSLOG_STRUCTURED_DATA='logdna@YourLogDNAnumber key="YourLogDNAKey" tag="docker"

(You can request keys via the #hydrophone-nodes channel in the Orcasound Slack. As of October, 2023, we are continuing to use AWS S3 for storage and LogDNA for live-logging and troubleshooting.)

Here are explanations of some of the .env fields:

• NODE_NAME should indicate your device and it's location, ideally in the form device_location (e.g. we call our Raspberry Pi staging device in Seattle rpi_seattle.
• NODE_TYPE determines what audio data formats will be generated and transferred to their respective AWS buckets.
• AUDIO_HW_ID is the card, device providing the audio data. Note: you can find your sound device by using the command "arecord -l". For Raspberry Pi hardware with pisound just use AUDIO_HW_ID=pisound
• CHANNELS indicates the number of audio channels to expect (1 or 2).
• FLAC_DURATION is the amount of seconds you want in each archived lossless file.
• SEGMENT_DURATION is the amount of seconds you want in each streamed lossy segment.

Supported combinations

Running local tests

In the repository directory (where you also put your .env file) first copy the compose file you want to docker-compose.yml. For example if you are raspberry pi and you want to use the prebuilt image then copy docker-compose.rpi-pull.yml to docker-compose. Then run docker-compose up -d. Watch what happens using htop. If you want to verify files are being written to /tmp or /mnt directories, get the name of your streaming service using docker-compose ps (in this case orcanode_streaming_1) and then do docker exec -it orcanode_streaming_1 /bin/bash to get a bash shell within the running container.

Running an end-to-end test

Once you've verified files are making it to your S3 bucket (with public read access), you can test the stream using a browser-based reference player. For example, with Bitmovin HLS/MPEG/DASH player you can use select HLS and then paste the URL for your current S3-based manifest (.m3u8 file) to listen to the stream (and observe buffer levels and bitrate in real-time).

Your URL should look something like this:

https://s3-us-west-2.amazonaws.com/dev-streaming-orcasound-net/rpi_seattle/hls/1526661120/live.m3u8

For end-to-end tests of Orcasound nodes, this schematic describes how sources map to the dev, beta, and live subdomains of orcasound.net --

(Google draw source and archived schematics) -- and you can monitor your development stream via the web-app using this URL structure:

dev.orcasound.net/dynamic/node_name

For example, with node_name = rpi_orcasound_lab the test URL would be dev.orcasound.net/dynamic/rpi_orcasound_lab.

Deployment

If you would like to add a node to the Orcasound hydrophone network, read through our Administrative Handbook and then contact admin@orcasound.net if you have any questions.

Built With

• FFmpeg - Uses ALSA to acquire audio data, then generates lossy streams and/or lossless archive files
• rsync - Transfers files locally from /tmp to /mnt directories
• s3fs - Used to transfer audio data from local device to S3 bucket(s)

Contributing

Please read CONTRIBUTING.md for details on our code of conduct, and the process for submitting pull requests.

Authors

• Steve Hicks - Raspberry Pi expert - Steve on Github
• Paul Cretu - Lead developer - Paul on Github
• Scott Veirs - Project manager - Scott on Github
• Val Veirs - Hydrophone expert - Val on Github

See also the list of orcanode contributors who have helped this project and the Orcasound Hacker Hall of Fame who have advanced both Orcasound open source code and the hydrophone network in the habitat of the endangered Southern Resident killer whales.

License

This project is licensed under the GNU Affero General Public License v3.0 - see the LICENSE.md file for details

Acknowledgments

• Thanks to the backers of the 2017 Kickstarter that funded the development of this open source code.
• Thanks to the makers of the Raspberry Pi, the Pisound HAT (Blokas in Lithuania), and the manufacturers who supply us with long-lasting, cost-effective hydrophones.
• Thanks to the many friends and backers who helped improve maintain nodes and improve the Orcasound app.