As per Relevance of the word standards, we have this rfc below:
Network Working Group M.
Request for Comment: 2029 D.
Category: Standards Track Sun Microsystems, Inc
October 1996
RTP Payload Format of Sun's CellB Video
Status of this
This document specifies an Internet standards track protocol for
Internet community, and requests discussion and suggestions
improvements. Please refer to the current edition of the "
Official Protocol Standards" (STD 1) for the standardization
and status of this protocol. Distribution of this memo is unlimited
This memo describes a packetization scheme for the CellB
encoding. The scheme proposed allows applications to transport
video flows over protocols used by RTP. This document is meant
implementors of video applications that want to use RTP and CellB
1.
The Cell image compression algorithm is a variable bit-rate
coding scheme. It provides "high" quality, low bit-rate
compression at low computational cost. The bytestream that
produced by the Cell encoder consists of instructional codes
information about the compressed image
For futher information on Cell compression technology, refer to [1].
Currently, there are two versions of the Cell compression technology
CellA and CellB. CellA is primarily designed for the encoding
stored video intended for local display, and will not be discussed
this memo
CellB, derived from CellA, has been optimized for network-based
applications. It is computationally symmetric in both encode
decode. CellB utilizes a fixed colormap and vector
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
2.1 RTP
The RTP timestamp is in units of 90KHz. The same timestamp value
used for all packet payloads of a frame. The RTP maker bit
the end of a frame
2.2 CellB
The packetization of the CellB bytestream is designed to make
resulting packet stream robust to packet loss. To achieve this goal
an additional header is added to each RTP packet to uniquely
the location of the first cell of the packet within the
frame. In addition, the width and height of the frame in pixels
carried in each CellB packet header. Although the size can
change between frames, it is carried in every packet to simplify
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,
are placed at the beginning of the payload for each RTP packet.
Cell X and the Cell Y Location coordinates are expressed as
coordinates, not pixel coordinates. Since cells represent 4x4
of pixels, the X or Y dimension of the cell coordinates range
value from 0 through 1/4 of the of the same dimension in
coordinates
2.3 Packetization
A packet can be of any size chosen by the implementor, up to a
frame. All multi-byte codes must be completely contained within
packet. In general, the implementor should avoid packet sizes
result in fragmentation by the network
Speer & Hoffman Standards Track [Page 2]
RFC 2029 RTP Payload Format October 1996
3.
1. "Cell Image Compression Byte Stream Description,"
ftp://playground.sun.com:/pub/multimedia/video
cellbytestream.ps.
2. Turletti, T., and C. Huitema, "RTP Payload
for H.261 Video Streams", RFC 2032, October 1996.
3. Schulzrinne, H., Casner, S., Frederick, R.,
V. Jacobson, "RTP: A Transport Protocol for Real-
Applications", RFC 1889, January 1996.
4. Schulzrinne, H., "RTP Profile for Audio and
Conferences with Minimal Control", RFC 1890,
January 1996.
4 Authors'
Michael F.
Sun Microsystems Computer
2550 Garcia Ave MailStop UMPK14-305
Mountain View, CA 94043
Voice: +1 415 786 6368
Fax: +1 415 786 6445
EMail: michael.speer@eng.sun.
Don
Sun Microsystems Computer
2550 Garcia Ave MailStop UMPK14-305
Mountain View, CA 94043
Voice: +1 415 786 6370
Fax: +1 415 786 6445
EMail: don.hoffman@eng.sun.
Speer & Hoffman Standards Track [Page 3]
RFC 2029 RTP Payload Format October 1996
Appendix A - Structure of the CellB Video
The CellB bytestream consists of cell codes, skip codes
quantization-table specific codes. These are now described
A.1 CellB Cell
Cell codes are 4 bytes in length, and describe a 4x4 pixel cell
There are two possible luminance (Y) levels for each cell, but
one pair of chrominance (UV) values. The CellB cell code is
below
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 M M M M M M M M M M M M M M M|U V U V U V U V|Y Y Y Y Y Y Y Y
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
4x4 Bitmask U/V Code Y/Y
The first two bytes of the cell code are a bitmask. Each bit in
mask represents a pixel in a 16-pixel cell. Bit 0 represents
value of the upper right-hand pixel of the cell, and subsequent
represent the pixels in row-major order. If a pixel's bit is set
the 4x4 Bitmask, then the pixel will be rendered with the pixel
. If the pixel's bit is not set in the bitmask, then
pixel's value will be rendered with the value .
bitmask for the cell is normalized so that the most significant
is always 0 (i.e., corresponding to ).
The U/V field of the cell code represents the chrominance component
This code is in index into a table of vectors that represents
independent components of chrominance
The Y/Y field of the cell code represents two luminance values (Y(0)
and Y(1)). This code is an index into a table of two-
luminance vectors
The derivation of the U/V and Y/Y tables is outside the scope of
memo. A complete discussion can be found in [1].
Speer & Hoffman Standards Track [Page 4]
RFC 2029 RTP Payload Format October 1996
A.2 CellB Skip
The single byte CellB skip code tells the CellB decoder to skip
next S+1 cells in the current video frame being decoded. The
number of cells that can be skipped is 32. The format of the
code is shown below
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|1 0 0 S S S S S
+-+-+-+-+-+-+-+-+
A.3 CellB Y/Y Table
The single byte "new Y/Y table" code is used to tell the decoder
the next 512 bytes are a new Y/Y quantization table. The code
the representation of the table are shown below. The
encoder/decoder pair in this document do not implement this
of the CellB compression. However, future CellB codecs may
this feature
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|1 1 1 1 1 1 1 0|
+-+-+-+-+-+-+-+-+
The format of the new Y/Y table is
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Y1_000 | Y2_000 | Y1_001 | Y2_001 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
.
.
.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Y1_254 | Y2_254 | Y1_255 | Y2_255 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Speer & Hoffman Standards Track [Page 5]
RFC 2029 RTP Payload Format October 1996
A.4 CellB U/V Table
The single byte "new U/V table" code is used to tell the decoder
the next 512 bytes represent a new U/V quantization table. The
is shown below. The sample encoder/decoder pair provided in
document do not implement this feature of the CellB compression
However, future CellB codecs may implement this feature
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|1 1 1 1 1 1 1 1|
+-+-+-+-+-+-+-+-+
The bytes of the new U/V quantization table are arranged as
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| U_000 | V_000 | U_001 | V_001 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
.
.
.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| U_254 | V_254 | U_255 | V_255 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Appendix B - Availability of
It is the viewpoint of Sun Microsystems, Inc, that CellB
publically available for use without any license
Speer & Hoffman Standards Track [Page 6]
if you see any problems within the linking, don't worry be happy,
this is version 0.1 of the Relevance System and you gotta expect some crappy subroutines sometimes,
just be content we did not write this in Java, which would have made this "bigger and better" HAHAHHA.
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