Embedded Media Coder (EMC)
We have developed a suite of embedded media codecs (EMC), which includes the embedded audio codec (EAC), the embedded image codec (EIC) and the embedded video codec (EVC). The suite is developed based on a key characteristic of media: the content of the media is important, the exact representation is not. Therefore, when we listen to a piece of music, or watch a piece of video, the content is of paramount importance, but the exact form and the exact compression ratio that the media is represented, e.g., whether at 128 kbps(kilo bits per second) or 127 kpbs, in 48 kHz sampling rate or in 96 kHz sampling rate, with resolution 352x288 or 176x144, can be flexibly changed. Sometime, the change is made to ensure that all media can fit into a target client device, e.g., you want to download all your music collection to the audio player, or you want to make sure that all music on your PC occupies a total of 1GB. Sometime, the change is made to fit the capacity of the client device. For example, if the player is mono, there is no point to include the stereo channel in the compressed media. EMC suite demonstrate a set of embedded media codec (or scalable media codec) where the compressed media can be quickly reshaped to fit the client device. In other words, you can reshape the compressed media "any size you want, in any form you want".
The framework of the traditional media codecs, such as the windows media audio and video codecs, vs that of the EMC can be shown in Fig. 1. A key component of the EMC is the parser, which takes in the master compressed bitstream and generates an application bitstream which is a subset of the master bitstream. The EMC parser may reshape the compressed bitstream in term of compression ratio, audio channel and sampling rate (for EAC), color component and resolution (for EIC/EVC ) and frame rate (for EVC).
Fig 1. EMC Framework
For more information and demo of the EMC suite, please following these links:
©Copyright by Jin Li, Feb. 23, 2003