This is in conformance with the W3c Recommendation, and after hours of searching the web I've seen dozens of examples that apparently work with this exact form. I know the API can be subject to change, but I can't find any hint that it has. Where am I going wrong?

This is in conformance with the W3C Recommendation, and after hours of searching the web I've seen dozens of examples that apparently work with this exact form. I know the API can be subject to change, but I can't find any hint that it has. Where am I going wrong?

Strangely, it doesn't fail when I try it in jsfiddle. I even tried running in jsfiddle the entire function in which this snippet exists, stubbing out a couple items. Below is the function that I'm trying to run. A "SyntaxError Dom Exception 12" occurs where indicated when the function is executed.

I have a working audio app, and I'm just trying to add background processing for later rendering using an OfflineAudioContext. If I define the OfflineAudoiContext in my init function, I don't get the syntax error there. But I need to define it in the createRenderData() function because I need to set the length and sample rate for each media source, and if I call the OfflineAudioContext constructor with no arguments, I get a TypeError. Also I don't see any way in the API to set the length and sample rate on an existing OfflineAudioContext.

AudioUI.createRenderData = function() { var url = BGAudioUI.renderQueue.pop(); if (url) { BGAudioUI.media = new Audio(url); BGAudioUI.media.addEventListener('durationchange', function() { console.log("background duration: " + BGAudioUI.media.duration); BGAudioUI.duration = BGAudioUI.media.duration; //BGAudioUI.allData = new Float32Array(Math.floor((AudioUI.context.sampleRate.toFixed() / AudioUI.downsampleFactor.toFixed() * BGAudioUI.duration)) + 1); //console.log("calculated sample rate: " + Math.floor(AudioUI.context.sampleRate / AudioUI.downsampleFactor.toFixed())); //console.log("duration: " + BGAudioUI.duration); BGAudioUI.offlineContext = new webkitOfflineAudioContext(2, 7*48000, 48000); //SyntaxError DOM Exception 12 occurs here BGAudioUI.mediaSource = BGAudioUI.offlineContext.createMediaElementSource(BGAudioUI.media); BGAudioUI.offlineContext.oncomplete = function(buffer) { data = buffer.getChannelData(0); console.log(data.length + " records processed offline"); }; BGAudioUI.offlineContext.startRendering(); BGAudioUI.media.play(); console.log("created background media source for " + BGAudioUI.media.src); }, false); BGAudioUI.media.load(); console.log("created background media object for " + BGAudioUI.media.src); } else { alert("Background rendering complete"); } };