VP2615 Datasheet, PDF (1/11 Pages) Mitel Networks Corporation – H.261 Decoder

Supersedes January 1996 edition, DS3479 - 3.0
VP2^VP6²1⁶¹5⁵
H.261 Decoder
DS3479 - 4.0 June 1996
FEATURES
s Inputs run length coded transform data
s Outputs 8 bit pixels in YUV block format
s Up to full CIF resolution and 30 Hz frame rates
s Supports motion compensation with up to 15 pixel
movement
s On chip frame store controller
s 100 pin QFP package
ASSOCIATED PRODUCTS
s VP510 Colour Space Converter
s VP520S Three Channel Video Filter
s VP2611 Integrated H261 Encoder
s VP2612 Video Multiplexer
s VP2614 Video Demultiplexer
DESCRIPTION
The VP2615 decoder forms part of a chip set for use in
video conferencing and video telephony applications. It
conforms to the CCITT H261 standard, and will decode data
coded with full or quarter CIF resolution at frame rates up to 30
Hz.
It accepts run length coded coefficients which have already
been error corrected and Huffman decoded, and produces
multiplexed YUV data in macro block format after a pipeline
delay of two MacroBlocks. As shown in Figure 1, other devices
in the chip set then convert this data into full resolution,
component or composite, video.
The incoming run length coded data is converted to
individual coefficient values in the correct order. Data
reconstruction is then performed on a block by block basis by
multiplying the quantized coefficients with the original
quantization value, and then applying the inverse cosine
transform. In the inter frame mode this data is then added to
the motion compensated block from the previous frame. This
block can be passed through a low pass filter when required.
A frame store controller produces addresses which allow the
best fit block to be read from the frame store, and which also
allow the store to be updated with reconstructed data. Refresh
cycles are generated when necessary.
SYSTEM
CONTROLLER
USER
INTERFACE
H261
BIT
STREAM
VP2614
VIDEO DEMUX
RECEIVE
BUFFER
32K X 8
RLC
DATA
ADR
VP2615
VIDEO
DECODER
CIF FRAME
STORE
128K X 16
FRMOUT
VP520
3 CHANNEL
VIDEO FILTER
Y/CR/CB
MACRO
BLOCK
DATA
ADR
DATA
TWO CIF
FRAME STORES
256K X 16
VP530
NTSC/PAL
ENCODER
VP510
COLOUR SPACE
CONVERTER
COMP
NTSC/PAL
RGB
OUTPUTS
Fig 1 : Typical Video Conferencing Receiver
1