Abe Estrada AbeEstrada

Reading waveform data in ffmpeg

When working on an audio player, I wanted to extract the audio waveform data to paint the audio waveform dynamically in the browser on a <canvas> element.

Initially I used the bbc/audiowaveform package but this proved problematic for a number of reasons. First I wasn't able to install that package (or build the binary) in macOS for local dev. The other big issue is that I was only able to figure out how to install it on Ubuntu, so I couldn't use it in Alpine (for Docker images) or other environments like cloud functions.

Initial approach

I found out from these docs it's possible to paint a waveform with ffmpeg by extracting raw audio data:

Regular Colors

Value	Color
\e[0;30m	Black
\e[0;31m	Red
\e[0;32m	Green
\e[0;33m	Yellow
\e[0;34m	Blue
\e[0;35m	Purple

	"use client";
	import { useState, useEffect, useRef } from "react";

	function SimpleRecordButton() {
	const [isRecording, setIsRecording] = useState(false);
	const [audioStream, setAudioStream] = useState(null);
	const [mediaRecorder, setMediaRecorder] = useState(null);
	const [audioBlob, setAudioBlob] = useState(null);
	const [recordingTime, setRecordingTime] = useState(0);
	const timerRef = useRef(null);

	//
	// VolumePopupView.swift
	//
	// Created by Alex Rosenberg on 1/24/24.
	//

	import SwiftUI
	import AVFoundation
	import MediaPlayer

	local wezterm = require 'wezterm'

	local themes = {}
	for k, _ in pairs(wezterm.get_builtin_color_schemes()) do
	table.insert(themes, k)
	end

	local fav_themes = {
	"SweetTerminal (Gogh)",
	"PaulMillr",

	<?php
	/*
	A simple PHP class to perform basic operations against Amazon S3 and compatible
	services. Requires modern PHP (7+, probably) with curl, dom, and iconv modules.

	Copyright 2022 Marco Arment. Released under the MIT license:

	Permission is hereby granted, free of charge, to any person obtaining a copy
	of this software and associated documentation files (the "Software"), to deal
	in the Software without restriction, including without limitation the rights

	var USERS = {
	protecteddir: [{
	username: 'user',
	password: 'pass',
	}],
	};

	//Response when auth is not valid.
	var response401 = {
	statusCode: 401,


	function string:contains(sub)
	return self:find(sub, 1, true) ~= nil
	end

	function string:startswith(start)
	return self:sub(1, #start) == start
	end

	function string:endswith(ending)