One of the most well-known features of HTML5 is its ability to play video and audio files natively. With HTML5’s <video> and <audio> tags, you do not need to have third-party software like Windows Media Player or Real Player to enjoy multimedia content. Your browser should be able to take care of audio and video files out of the box, independent of the system. Unfortunately, due to a lack of consensus, HTML5 specifications don’t actually specify the codecs in which the multimedia content must be encoded in. This is similar to how to image tag works – the image tag can be used to embed images in all popular image formats including BMP, JPEG, GIF, and PNG. Initially, Internet Explorer and Apple supported the proprietary H.264 technology for the video tag, and Opera and Mozilla backed Ogg Theora. While H.264 posed licensing challenges, Ogg Theora was widely believed to be an inferior solution. Google tried to solve the conundrum by stepping in and proposing WebM, which uses a superior VP8 video codec and Vorbis Ogg audio codec. For audio tag also something similar happened with some browsers throwing their weight behind Ogg and others supporting AAC.
Now, Mozilla is proposing a new audio format called Opus as an alternative to Ogg and AAC formats that have emerged as the de facto choices for the audio tag. Opus is a completely free audio format that was developed by collaboration between members of the IETF Internet Wideband Audio Codec working group, which includes Mozilla, Microsoft, Xiph.Org, Broadcom, and Octasic.
Mozilla is promising better quality to size ratio for Opus than its competitors. According to its tests, Opus is the best-in-class for live streaming and static file playback. In fact, it is being heralded as the first audio codec to be well-suited for both interactive and non-interactive applications. Mozilla’s listening tests show that at 64 kbps, Opus sounds better than both HE-AAC and Vorbis, and a 64 kbps Opus file sounds as good as a 96 kbps MP3 file.
Mozilla is adding support for Opus with Firefox 15 beta, and is hoping that other browser manufacturers will follow suit.