ZR36050 Просмотр технического описания (PDF) - Unspecified

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ZR36050

JPEG IMAGE COMPRESSION PROCESSOR

Unspecified 

ADVANCE INFORMATION

ZR36050

lated code volume against TCV_NET on every cycle. If the

accumulated code volume exceeds the TCV_NET value, then

the ZR36050 sets the TCVOVF status bit to “1”, activates the INT

signal and aborts the encoding process. The Target Code

Volume is in bits unit for the compressed data excluding the

marker segments. TCV_NET is represented as a 32 bit fixed

point binary number.

End-Of-Block codes and bit and byte stuffings at the completion

of the Statistical Pass (ACV_DATA), and (2) The Net Code

Volume in bits including the coded data, End-Of-Block codes,

and bit and byte stuffings at the completion of every encoding

operation, excluding the Statistical Pass (ACV_NET). Both

ACV_DATA and ACV_NET are represented as a 32 bit fixed

point binary numbers.

TCV_DATA Register

Target Data Code Volume. Used only in Auto Bit Rate Control

and Statistical Pass. TCV_DATA is used by the ZR36050 to cal-

culate the new Scale Factor (SF) and Allocation Factor (AF) after

a Statistical Pass. It is the Target Code Volume in bits for the

compressed data excluding the marker segments, the End Of

Block codes, the bit and byte stuffings; (i.e., it is the target code

volume for the parts of the compressed data which contain only

Huffman codes and the appended data to each code).

TCV_DATA is represented as a 32 bit fixed point binary number.

SF Register

Scale Factor. Scale Factor is used for scaling the quantization

tables values. SF should be provided to the ZR36050 as a

parameter at the beginning of every encoding operation. SF is

represented as a 16 bit fixed point binary number, with 8 bits

after the binary point.

AF Register

Allocation Factor. Used only in Compression Pass with Bit Rate

Control. AF is used to compute the Allocated Code Volume for

each block. The AF is computed by the ZR36050 and written to

the AF register at the end of the Statistical Pass. This value can

then be used in a Compression Pass with Bit Rate Control. Oth-

erwise the user is responsible for inputting the AF value into the

Internal Memory register prior to performing a Compression

Pass with Bit Rate Control. AF is represented as a 24 bit fixed

point binary number, with 19 bits after the binary point.

Compressed Data Register

This register is used in Slave mode Compressed Data Transfer.

During the encoding process, ZR36050 loads the compressed

data into this register for the host to read. Similarly, during the

decoding process, the host loads the compressed data into this

register for the ZR36050 to read.

ACT Register

This register contains the total activity of the image. ACT is

updated at the end of Statistical Pass and Auto bit rate control

encoding modes. It is represented as a 32 bit fixed point binary

number.

ACV_TRUN

This register contains the total number of truncated bits of the

frame as a result of block truncation in Compression Pass with

Bit Rate Control and Auto Bit Rate Control encoding modes.

ACV_TRUN is updated at the end of Compression Pass with Bit

Rate Control and Auto Bit Rate Control encoding modes. It is

represented as a 32 bit fixed point binary number.

ACV Register

Accumulated Code Volume. ACV register is used: (1) To store

the Net Code Volume in bits unit excluding marker segments,

32

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