ADV601LCJST View Datasheet(PDF) - Analog Devices

Part Name

Description

Manufacturer

ADV601LCJST

Ultralow Cost Video Codec

Analog Devices 

ADV601LC

INTERNAL ARCHITECTURE

The ADV601LC is composed of eight blocks. Three of these

blocks are interface blocks and five are processing blocks. The

interface blocks are the Digital Video I/O Port, the Host I/O

Port, and the external DRAM manager. The processing blocks

are the Wavelet Kernel, the On-Chip Transform Buffer, the

Programmable Quantizer, the Run Length Coder, and the

Huffman Coder.

Digital Video I/O Port

Provides a real-time uncompressed video interface to support a

broad range of component digital video formats, including “D1.”

Host I/O Port and FIFO

Carries control, status, and compressed video to and from the

host processor. A 512 position by 32-bit FIFO buffers the com-

pressed video stream between the host and the Huffman Coder.

DRAM Manager

Performs all tasks related to writing, reading, and refreshing the

external DRAM. The external host buffer DRAM is used for

reordering and buffering quantizer input and output values.

Wavelet Kernel (Filters, Decimator, and Interpolator)

Gathers statistics on a per field basis and includes a block of

filters, interpolators, and decimators. The kernel calculates

forward and backward bi-orthogonal, two-dimensional, sepa-

rable wavelet transforms on horizontal scanned video data. This

block uses the internal transform buffer when performing wave-

let transforms calculated on an entire image’s data and so

eliminates any need for extremely fast external memories in

an ADV601LC-based design.

On-Chip Transform Buffer

Provides an internal set of SRAM for use by the wavelet trans-

form kernel. Its function is to provide enough delay line storage

to support calculation of separable two dimensional wavelet

transforms for horizontally scanned images.

Programmable Quantizer

Quantizes wavelet coefficients. Quantize controls are calculated

by the external DSP or host processor during encode operations

and de-quantize controls are extracted from the compressed bit

stream during decode. Each quantizer Bin Width is computed

by the BW calculator software to maintain a constant com-

pressed bit rate or constant quality bit rate. A Bin Width is a per

block parameter the quantizer uses when determining the num-

ber of bits to allocate to each block (sub-band).

Run Length Coder

Performs run length coding on zero data and models nonzero

data, encoding or decoding for more efficient Huffman coding.

This data coding is optimized across the sub-bands and varies

depending on the block being coded.

Huffman Coder

Performs Huffman coder and decoder functions on quantized

run-length coded coefficient values. The Huffman coder/de-

coder uses three ROM-coded Huffman tables that provide ex-

cellent performance for wavelet transformed video.

GENERAL THEORY OF OPERATION

The ADV601LC processor’s compression algorithm is based on

the bi-orthogonal (7, 9) wavelet transform, and implements field

independent sub-band coding. Sub-band coders transform two-

dimensional spatial video data into spatial frequency filtered

sub-bands. The quantization and entropy encoding processes

provide the ADV601LC’s data compression.

The wavelet theory, on which the ADV601LC is based, is a new

mathematical apparatus first explicitly introduced by Morlet and

Grossman in their works on geophysics during the mid 80s.

This theory became very popular in theoretical physics and

applied math. The late 80s and 90s have seen a dramatic growth

in wavelet applications such as signal and image processing. For

more on wavelet theory by Morlet and Grossman, see Decompo-

sition of Hardy Functions into Square Integrable Wavelets of Con-

stant Shape (journal citation listed in References section).

ENCODE

PATH

DECODE

PATH

WAVELET

KERNEL

FILTER BANK

ADAPTIVE

QUANTIZER

RUN LENGTH

CODER &

HUFFMAN

CODER

COMPRESSED

DATA

Figure 2. Encode and Decode Paths

References

For more information on the terms, techniques and underlying

principles referred to in this data sheet, you may find the follow-

ing reference texts useful. A reference text for general digital

video principles is:

Jack, K., Video Demystified: A Handbook for the Digital Engineer

(High Text Publications, 1993) ISBN 1-878707-09-4

Three reference texts for wavelet transform background infor-

mation are:

Vetterli, M., Kovacevic, J., Wavelets And Sub-band Coding

(Prentice Hall, 1995) ISBN 0-13-097080-8

Benedetto, J., Frazier, M., Wavelets: Mathematics And Applica-

tions (CRC Press, 1994) ISBN 0-8493-8271-8

Grossman, A., Morlet, J., Decomposition of Hardy Functions into

Square Integrable Wavelets of Constant Shape, Siam. J. Math.

Anal., Vol. 15, No. 4, pp 723-736, 1984

REV. 0

–3–

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