Context: I'm trying to create an audio visualizer using the Web Audio API with createMediaElementSource() very similarly to the model explained in this tutorial. The hosting service my client is using for their audio inserts a 302 redirect before the actual media, to track listening data.
Problem: In Safari, when I attach an AudioContext to an audio element that is linked to a source with a 302 redirect in front of it, it outputs silence instead of normal audio without any errors in the log. By contrast I've tested Chrome and Firefox, and they both work fine with no issues.
In the demo above, all three buttons attach and play the same audio source, but in the second and third it goes through the redirect first. The second attaches an AudioContext as well, while the third just plays the audio normally with no visual.
I posted about this issue last month and it was suggested that the problem was some missing CORS headers on the 302 redirect. However, I am now testing my own redirect server instead of using the hosting service, so that I can test my own CORS rules (see below). The issue remains even with these headers set, so this makes me think it's a bug in Safari with 302 redirects. What I'd like to know is A) Are there any other cross origin headers I can try adding that may resolve the issue, and B) If it is indeed a Safari bug, where do I go to report it and how long from that point until someone addresses it.
Headers I've set for my 302 redirect:
Access-Control-Allow-Origin:*
Access-Control-Expose-Headers:connection,content-length,last-modified,etag,content-type,via,cache-control,accept-ranges,age,content-range,date,x-served-by,x-cache,x-cache-hits,x-timer,access-control-allow-origin,access-control-allow-methods,vary,server,x-final-url
Access-Control-Allow-Methods:GET,OPTIONS
Update: I've now reported this as a bug, and the Webkit devs have isolated the check causing the issue.