VP2611 Datasheet, PDF (1/14 Pages) Mitel Networks Corporation – H.261 Encoder

Supersedes June 1996 edition, DS3487 - 4.0
VP2611
VP2611
H.261 Encoder
DS3487 - 4.1 December 1998
FEATURES
s Fully integrated H261 video encoder
s Up to full CIF resolution and 30 Hz frame rates
s Inputs YUV data in 8 x 8 sub block format
s Outputs run length coded coefficients
s On chip motion vector estimator with +/-7 pixel search
window
s Addresses and control generated internally for DRAM
frame store
s QFP package
ASSOCIATED PRODUCTS
s VP510 Colour Space Converter
s VP520S CIF/QCIF Converter
s VP2612 Video Multiplexer
s VP2614 Video Demultiplexer
s VP2615 H.261 Decoder
DESCRIPTION
The VP2611 Video Compression Source Coder forms part
of a chip set used in video conferencing, video telephony and
multimedia applications. It produces data which conforms to
the H261 standard for video compression with rates between
64K and 2M bits per second. With a 27 MHz clock the device
will accept data produced to full CIF resolution at 30 Hz frame
rates. The pipeline latency through the device is only 3 macro
block periods.
The VP2611 contains all the elements necessary for the
compression algorithm. It incorporates a Motion Vector Esti-
mator which performs a +/- 7 pixel search. The decision to use
inter or intra frame compression is made by the device, and the
selected data blocks are read from the frame store. New or
difference data is then passed through a Discrete Cosine
Transformer and quantized. Data from the quantizer is also
inverse quantized and passed through an Inverse Discrete
Cosine Transformer. This re-constructed data is then written
to the frame store for use in the next frame period.This frame
store is managed by an internal DRAM controller, and no
external logic is needed.
The input data must be in YUV space, and must also
conform to the six sub blocks per macro block format defined
by H261. Any conversion from RGB format is performed by
the VP510 Colour Space Converter. Any reduction in spatial
resolution, down to CIF or QCIF requirements, is done by the
VP520 Three Channel Video Filter.
The quantized data is zig-zag scanned and run length
coded before being output, together with block information
and motion vectors.
R
VP510
G COLOUR SPACE
CONVERTER
B
NTSC
PAL
COMP VIDEO
DECODER
VIDEO
SYNC
USER
INTERFACE
Y
Cr/Cb
VP520
3 CHANNEL
VIDEO FILTER
REQYUV
FRMIN
MBLK'S
ADDR
DATA
CIF FRAME
STORE
16 X128K
SYSTEM
CONTROLLER
VP2611
RLC DATA
INTEGRATED
VIDEO ENCODER ^FLAGS
CIF FRAME
STORE
16X128K
CCIR601 RESOLUTION
Y 720 X 288 Cr/Cb 360 x 288 PAL
Y 720 X 240 Cr/Cb 360 x 240
NTSC
CIF RESOLUTION
Y 352 X 288
Cr/Cb 176 x 144
VP2612
VIDEO
MULTIPLEXER
TX BUFFER
32K X 8
H261
BIT
STREAM
64kb to 2Mb/s
Fig 1 : Typical Video Conferencing Transmission System
1