Develop open-source JavaScript 3gp/amr audio codec

I need a Javascript codec that converts 3gp/amr (not quite sure of the exact type) audio files produced by Android devices into a format playable within Chrome browsers. The codec has to operate 100% in the browser, with no servers involved. There is a Javascript amr codec available here: [login to view URL] It does not work for the audio files I want to play, but I suspect a similar approach could work. I'm attaching a sample audio file produced by my android device for testing. The code should use a permissive free software license. Some additional context: [login to view URL]