Video Coding for Streaming Media Delivery on the Internet

Gregory J. Conklin et al.

• The paper [pdf]
• Presentation slides [ppt]

Summary:

Multimedia streaming presents many new challenges in addition to standard multimedia encoding problems. Due to the dynamic nature of video, many original codecs produced variable bit rate data streams, which are difficult to stream across a network. Also, providing end users random access to streamed videos requires the insertion of additional Intra frames, which can diminish achievable compression rates. Finally, due to potentially diverse capacity of end users’ connections, a scalable or adaptive streaming technique is desirable.

The RealVideo 8 system employs a number of techniques to solve these problems. The fundamental component of the RealVideo system is the SureStream file format, which allows for multiple streams of varying quality and bit rates for a video to be stored in a single file. Clients can subscribe to a particular stream through the use of an Adaptive Stream Management protocol. Ideally, channel performance statistics could be sent automatically from client to server to ensure the adaptive transmission of the most appropriate stream; the use of splitters or proxies can also be incorporated to mitigate server resource consumption. Streams are strategically passed through inverse telecine and de-interlacing filters to reduce potential problems introduced by analog sources if necessary and are then encoded with a motion-compensated hybrid algorithm. The encoding process is scalable with respect to CPU consumption to facilitate encoding of live events on resource-constrained machines. Finally, a number of client-side video postprocessing features, such as the frame rate upsampler, which can interpolate missing intermediary frames, are applied to improve the qualitative appearance of the video.

Group Discussion:

• This system does not address a third type of streaming, interactive conferencing
• Many solutions proposed by this paper are not actually implemented in the Real system. For example, dynamic stream adaptation, dynamically scalable encoding, multiple-description coding are just a few ideas suggested but unimplemented ideas presented in the paper.
• Dynamic prediction of both network capacity and encoded video stream bit rates questionable—both internet and video exhibit self-similarity
• Adaptive Stream Management protocol very difficult to manage
• Application of filters before encoding process beneficial
• Out of Microsoft, Quicktime, and RealOne, RealOne was the only company willing to publish a paper about their system

References:

• https://helixcommunity.org/ — The Helix community is a collaborative effort among Real, independent developers, and leading companies to extend the Helix DNA? platform, the first open multi-format platform for digital media creation, delivery and playback.