|ADV601LC||Ultralow Cost Video Codec|
|ADV601LC Datasheet PDF : 44 Pages |
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
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.
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.
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.
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).
Figure 2. Encode and Decode Paths
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-
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
|Direct download click here|
|Share Link :|