Which MIME Types are supported by MediaRecorder on Safari?

Question

I'm mainly interested in audio MIME types but it would be helpful if someone can provide a list of all MIME types supported by Safari's MediaRecorder.

I've been unable to find any documentation on the matter. So far I've ran MediaRecorder.isTypeSupported(...) with all audio MIME types that are supported by Chrome and Firefox but none of them seem supported.

Answer 1

Currently, it seems only audio/mp4 and video/mp4 containers are supported, at least they're the only values that MediaRecorder.isTypeSupported() would return as valid: [source code]

if (!equalLettersIgnoringASCIICase(containerType, "audio/mp4") && !equalLettersIgnoringASCIICase(containerType, "video/mp4"))
   return false;

And then the only codecs that are accepted by this same method are AVC1 for the video and MP4A for the audio.

if (!startsWithLettersIgnoringASCIICase(codec, "avc1") && !startsWithLettersIgnoringASCIICase(codec, "mp4a"))
   return false;

Now, there seems to be some "Experimental Features" flags we can switch in the "Develop" menu regarding adding support for webm decoders or adding VP9 support for WebRTC but there doesn't seem to be anything for the MediaRecorder...