RTP Payload Format of Sun's CellB Video Encoding (RFC2029)
Original Publication Date: 1996-Oct-01
Included in the Prior Art Database: 2019-Feb-16
Internet Society Requests For Comment (RFCs)
M. Speer: AUTHOR [+1]
This memo describes a packetization scheme for the CellB video encoding. The scheme proposed allows applications to transport CellB video flows over protocols used by RTP. This document is meant for implementors of video applications that want to use RTP and CellB. [STANDARDS-TRACK]
Network Working Group M. Speer Request for Comment: 2029 D. Hoffman Category: Standards Track Sun Microsystems, Inc. October 1996
RTP Payload Format of Sun’s CellB Video Encoding
Status of this Memo
This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.
This memo describes a packetization scheme for the CellB video encoding. The scheme proposed allows applications to transport CellB video flows over protocols used by RTP. This document is meant for implementors of video applications that want to use RTP and CellB.
The Cell image compression algorithm is a variable bit-rate video coding scheme. It provides "high" quality, low bit-rate image compression at low computational cost. The bytestream that is produced by the Cell encoder consists of instructional codes and information about the compressed image.
For futher information on Cell compression technology, refer to . Currently, there are two versions of the Cell compression technology: CellA and CellB. CellA is primarily designed for the encoding of stored video intended for local display, and will not be discussed in this memo.
CellB, derived from CellA, has been optimized for network-based video applications. It is computationally symmetric in both encode and decode. CellB utilizes a fixed colormap and vector quantization techniques in the YUV color space to achieve compression.
Speer & Hoffman Standards Track [Page 1]
RFC 2029 RTP Payload Format October 1996
2. Network Packetization and Encapsulation
2.1 RTP Usage
The RTP timestamp is in units of 90KHz. The same timestamp value is used for all packet payloads of a frame. The RTP maker bit denotes the end of a frame.
2.2 CellB Header
The packetization of the CellB bytestream is designed to make the resulting packet stream robust to packet loss. To achieve this goal, an additional header is added to each RTP packet to uniquely identify the location of the first cell of the packet within the current frame. In addition, the width and height of the frame in pixels is carried in each CellB packet header. Although the size can only change between frames, it is carried in every packet to simplify the packet encoding.
0 1 2 3 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Cell X Location | Cell Y Location | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Width of Image | Height of Image | +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ | Compressed CellB Data | | .... | +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
All fields are 16-bit unsigned integers in network byte order, and are placed at the begin...