Adblock Radio

A library to block ads on live radio streams and podcasts. Machine learning meets Shazam.

Engine of AdblockRadio.com. Demo standalone player available here.

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Overview

A technical discussion is available here.

Radio streams are downloaded in predictor.js with the module adblockradio/stream-tireless-baler. Podcasts are downloaded in predictor-file.js.

In both cases, audio is then decoded to single-channel, 22050 Hz PCM with ffmpeg.

Chunks of about one second of PCM audio are piped into two sub-modules:

• a time-frequency analyser (predictor-ml/ml.js), that analyses spectral content with a neural network.
• a fingerprint matcher (predictor-db/hotlist.js), that searches for exact occurrences of known ads, musics or jingles.

In post-processing.js, results are gathered for each audio segment and cleaned.

A Readable interface, Analyser, is exposed to the end user. It streams objects containing the audio itself and all analysis results.

On a regular laptop CPU and with the Python time-frequency analyser, computations run at 5-10X for files and at 10-20% usage for live stream.

Getting started

Installation

Mandatory prerequisites:

You need Node.js (>= v10.12.x, but < 11) and NPM. Download it here. Pro-tip: to manage several node versions on your platform, use NVM.

On Debian Stretch:

apt-get install -y git ssh tar gzip ca-certificates build-essential sqlite3 ffmpeg

Note: works on Jessie, but installing ffmpeg is a bit painful. See here and there.

Optional prerequisites:

For best performance (~2x speedup) you should choose to do part of the computations with Python. Additional prerequisites are the following: Python (tested with v2.7.9), Keras (tested with v2.0.8) and Tensorflow (tested with CPU v1.4.0 and GPU v1.3.0).

On Debian:

apt-get install python-dev portaudio19-dev
pip install python_speech_features h5py numpy scipy keras tensorflow zerorpc sounddevice psutil

Note: if you do not have pip follow these instructions to install it.

Then install this module:

git clone https://github.com/adblockradio/adblockradio.git
cd adblockradio
npm install

Testing

Validate your installation with the test suite:

npm test

Command-line demo

At startup and periodically during runtime, filter configuration files are automatically updated from adblockradio.com/models/:

• a compatible machine-learning model (model.keras or model.json + group1-shard1of1), for the time-frequency analyser.
• a fingerprint database (hotlist.sqlite), for the fingerprint matcher.

Live stream analysis

Run the demo on French RTL live radio stream:

node demo.js

Here is a sample output of the demo script, showing an ad detected:

{
	"gain": 74.63,
	"ml": {
		"class": "0-ads",
		"softmaxraw": [
			0.996,
			0.004,
			0
		],
		"softmax": [
			0.941,
			0.02,
			0.039
		],
		"slotsFuture": 4,
		"slotsPast": 5
	},
	"hotlist": {
		"class": "9-unsure",
		"file": null,
		"matches": 1,
		"total": 7
	},
	"class": "0-ads",
	"metadata": {
		"artist": "Laurent Ruquier",
		"title": "L'été des Grosses Têtes",
		"cover": "https://cdn-media.rtl.fr/cache/wQofzw9SfgHNHF1rqJA3lQ/60v73-2/online/image/2014/0807/7773631957_laurent-ruquier.jpg"
	},
	"streamInfo": {
		"url": "http://streaming.radio.rtl.fr/rtl-1-44-128",
		"favicon": "https://cdn-static.rtl.fr/versions/www/6.0.637/img/apple-touch-icon.png",
		"homepage": "http://www.rtl.fr/",
		"audioExt": "mp3"
	},
	"predictorStartTime": 1531150137583,
	"playTime": 1531150155250,
	"tBuffer": 15.98,
	"audio": ...
}

Podcast analysis

It is also possible to analyse radio recordings. Run the demo on a recording of French RTL radio, including ads, talk and music:

node demo-file.js

Gradual outputs are similar to those of live stream analysis. An additional post-processing specific to recordings hides the uncertainties in predictions and shows big chunks for each class, with time stamps in milliseconds, making it ready for slicing.

[
	{
		"class": "1-speech",
		"tStart": 0,
		"tEnd": 58500
	},
	{
		"class": "0-ads",
		"tStart": 58500,
		"tEnd": 125500
	},
	{
		"class": "1-speech",
		"tStart": 125500,
		"tEnd": 218000
	},
	{
		"class": "2-music",
		"tStart": 218000,
		"tEnd": 250500
	},
	{
		"class": "1-speech",
		"tStart": 250500,
		"tEnd": 472949
	}
]

Note that when analyzing audio files, you still need to provide the name of a radio stream, because the algorithm has to load acoustic parameters and DB of known samples. Analysis of podcasts not tied to a radio is not yet supported, but may possibly be in the future.

Documentation

Usage

Below is a simple usage example. More throughout usage examples are available in the tests:

• file/podcast analysis: test/file.js
• live stream analysis: test/online.js
• record a live stream, analyse it later: test/offline.js

const { Analyser } = require("adblockradio");

const abr = new Analyser({
	country: "France",
	name: "RTL",
	config: {
		...
	}
});

abr.on("data", function(obj) {
	...
});

Property	Description	Default
country	Country of the radio stream according to radio-browser.info	None
name	Name of the radio stream according to radio-browser.info	None
file	File to analyse (optional, analyse the live stream otherwise)	None

Methods

Acoustic model and hotlist files are refreshed automatically on startup. If you plan to continuously run the algo for a long time, you can trigger manual updates. Note those methods are only available in live stream analysis mode.

Method	Parameters	Description
refreshPredictorMl	None	Manually refresh the ML model (live stream only)
refreshPredictorHotlist	None	Manually refresh the hotlist DB (live stream only)
refreshMetadata	None	Manually refresh the metadata scraper (live stream only)
stopDl	None	Stop Adblock Radio (live stream only)

Optional configuration

Properties marked with a * are meant to be used only with live radio stream analysis, not file analysis where they are ignored.

Scheduling

Property	Description	Default
predInterval	send stream status to listener every N seconds	1
saveDuration*	if enabled, save audio file and metadata every N predInterval times	10
modelUpdatesInterval	if enabled, update model files every N minutes	60

Switches

Property	Description	Periodicity	Default
enablePredictorMl	perform machine learning inference	predInterval	true
JSPredictorMl	use tfjs instead of Python for ML inference (slower)	false
enablePredictorHotlist	compute audio fingerprints and search them in a DB	predInterval	true
saveAudio*	save stream audio data in segments on hard drive	saveDuration	true
saveMetadata	save a JSON with predictions	saveDuration	true
fetchMetadata*	gather metadata from radio websites	saveDuration	true
modelUpdates	keep ML and hotlist files up to date	modelUpdatesInterval	true

Paths

Property	Description	Default
modelPath	directory where ML models and hotlist DBs are stored	process.cwd() + '/model'
modelFile	path of ML file relative to modelPath	country + '_' + name + '/model.keras'
hotlistFile	path of the hotlist DB relative to modelPath	country + '_' + name + '/hotlist.sqlite'
saveAudioPath*	root folder where audio and metadata are saved	process.cwd() + '/records'

Output

Readable streams constructed with Analyser emit objects with the following properties. Some properties are only available when doing live radio analysis. They are marked with a *. Other specific to file analysis are marked with **.

• audio*: Buffer containing a chunk of original (compressed) audio data.

• ml: null if not available, otherwise an object containing the results of the time-frequency analyser

  • softmaxraw: an array of three numbers representing the softmax between ads, speech and music.
  • softmax: same as softmaxraw, but smoothed in time with slotsFuture data points in the future and slotsPast data points in the past. Smoothing weights are defined by consts.MOV_AVG_WEIGHTS in post-processing.js.
  • class: either 0-ads, 1-speech, 2-music or 9-unsure. The classification according to softmax.

• hotlist: null if not available, otherwise an object containing the results of the fingerprint matcher.

  • file: if class is not "9-unsure", the reference of the file recognized.
  • total: number of fingerprints computed for the given audio segment.
  • matches: number of matching fingerprints between the audio segment and the fingerprint database.
  • class: either 0-ads, 1-speech, 2-music, 3-jingles or 9-unsure if not enough matches have been found.

• class: final prediction of the algorithm. Either 0-ads, 1-speech, 2-music, 3-jingles or 9-unsure.

• metadata*: live metadata, fetched and parsed by the module adblockradio/webradio-metadata.

• streamInfo*: static metadata about the stream. Contains stream url, favicon, bitrate in bytes / s, audio files extension audioExt (mp3 or aac) and homepage URL.

• gain: a dB value representing the average volume of the stream. Useful if you wish to normalize the playback volume. Calculated by mlpredict.py.

• tBuffer*: seconds of audio buffer. Calculated by adblockradio/stream-tireless-baler.

• predictorStartTime*: timestamp of the algorithm startup. Useful to get the uptime.

• playTime*: approximate timestamp of when the given audio is to be played. TODO check this.

• tStart**: lower boundary of the time interval linked with the prediction (in milliseconds)

• tEnd**: upper boundary of the time interval linked with the prediction (in milliseconds)

Supported radios

The list of supported radios is available here.

Note to developers

Integrations of this module are welcome. Suggestions are available here.

A standalone demo player for web browsers is available here.

License

See LICENSE file.

Your contribution to this project is welcome, but might be subject to a contributor's license agreement.