Contents

1 Single Layer Coding (SLC)

• Most audio and image/video codecs generate non-scalable streams. In the case of video, only one quality, resolution and picture-rate are available at decoding time.
• The decoding of a single layered stream generates a reconstruction whose quality is linearly proportional to the amount of decoded data.

2 Multiple Layer Coding (MLC)

• A media encoded in several layers can be decoded to provide (in the case of video) different picture-rates (time scalability), different resolutions (spatial scalability) and different qualities (quality scalability).
• In some codecs (such as JPEG2000), spatial random access it is available ROI (Region-Of-Interest) or WOI (Window-Of-Interest) scalability. ROI is used in special imaging, such as mammography. WOI can useful in the retrieving of high-resolution video sequences such as JHelioviewer.

3 Multiple Description Coding (MDC)

• Multiple description codecs provides a set of partially redundant streams so that the quality of the reconstructions improve with the number of descriptions decoded.
• An example of this type of encoding is the scene segmentation (video object coding) provided by MPEG-4.

4 Media simulcast

• In transmission scenarios, a source can store several copies of the same media, althought variying the temporal resolution, spatial resolution and/or quality.
• Obviously, this is quite redundant at the source side. However, as it will be shown after, adaptive services can be provided with this technique, such as in YouTube.