Sistema Operativo: Windows a Apple iOS
Dispositivo: PC a iPhone 6, iPhone XS, iPhone XR, iPhone 11, iPhone 6S
Navegador: Safari, Google Chrome
Errores: [código nativo]: 1 Rechazo de promesa no manejado: NotSupportedError: la operación no es compatible.
[código nativo]: 1 Rechazo de promesa no manejado: NotAllowedError: el agente de usuario o la plataforma no permiten la solicitud en el contexto actual, posiblemente porque el usuario negó el permiso.

Código:

 let started = false; let audio = new Audio(); audio.src = "data:audio/mpeg;base64,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"; ... class FrequencyData { constructor() { this.audioContext = null; this.source = null; this.analyser = null; } getFrequencies() { if (!this.audioContext) { this.audioContext = new window.AudioContext(); this.source = this.audioContext.createMediaElementSource(audio); this.analyser = this.audioContext.createAnalyser(); } this.source.connect(this.analyser); this.analyser.connect(this.audioContext.destination); return [new Uint8Array(this.analyser.frequencyBinCount), this.analyser]; } } let frequencyData = new FrequencyData(); window.addEventListener("touchstart", function() { // Allows for audio to be played without needing user interaction every time. if (!started) { audio.play(); started = true; } }); ... webSocket.onmessage = function(event) { let message = event.data; audio.src = ""; ... audio.src = "data:audio/mp3;base64," + message; audio.play(); render(); ...

Los errores ocurren al mismo tiempo. Los probé en mi iPhone y en iPhones alojados en browserstack para poder ver la consola del desarrollador. El audio se envía a través de un websocket alojado en mi PC y se envía al cliente, que son los teléfonos. Funcionó mientras lo probaba en otras PC. El audio se envía como una cadena base64 y son archivos mp3.