HTML5 baseline codec is a video and audio formats supported by all browsers. As a result, we can rely on this media element for our development.

Codec audio or video data can be compared to compressed data and is delivered in a pocket from the source to a video or audio player. There are quite a few codec formats in existence. In addition, there are encapsulation formats that are used to package data. For example, there are MPEG, WMV, AVI, MOV, FLV and MP4 encapsulation formats. This formats acts as containers for the video or audio data during transmission of this data over the wire. In addition, there are many more different video and audio codes exist. For example, there are MPEG-1, MPEG-2, H.263, VP8, FLAC, MPEG-4 AAC, WAV and Dirac.

Each codec can be encapsulated into corresponding containers. Moreover, some of the codec formats can be encapsulated into containers not designed for them. However, each codec has corresponding container designed for it and it must be used as prescribed in order to achieve optimal performance.

There are open source and royalty free video file formats in the making. Google supports WebM that is designed to overcome many limitations of other open source formats. The WebM video codec is designed specifically with HTML5 in mind. Moreover, many hardware and software companies are lining behind this format making it more attractive for developers to learn and use. 

Here is a list of browsers and audio/video formats that they support

• Safari - MP4 H.264/AAC
• Chrome - Ogg Theora, MP4 H.264/AAC, WebM
• Firefox - Ogg Theora, WebM
• IE - MP4 H.264/AAC
• Opera - Ogg Theora, WebM

It’s important to note that YouTube runs audio and video content using WebM codec.