ZR36050 Просмотр технического описания (PDF) - Zoran Corporation

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ZR36050

JPEG IMAGE COMPRESSION PROCESSOR

Zoran Corporation 

ADVANCE INFORMATION

ZR36050

JPEG MARKER SEGMENTS

The formats of the marker segments are implemented according to the JPEG standard IS 10918–1. These segments are: SOF, SOS,

DRI, DNL, DQT, DHT, APP, and COM. The SOI, EOI and RSTn are supported internally.

The JPEG marker segments contained in the compressed data are saved into the Internal Memory during the decoding mode. The

starting location of each JPEG marker segment in the Internal Memory is fixed in both encoding and decoding modes. However the

length and the content of each marker segment may vary. Table 11 represents the JPEG markers segments for the JPEG Baseline

mode. The JPEG Lossless marker segments are described in Table 12.

Table 11. JPEG Baseline Marker Segments

Address

Content

Description

040

SOF0[FF]

Start of frame. This variable length segment contains up to 34 bytes that define 1–8 components and is used

both in the encoding and decoding modes. If there are fewer than 8 components, the remaining memory

locations are left unused

041

SOF0[C0]

042

LEN(H)

043

LEN(L)

044

P[8]

Precision

045

Y(H)

Most significant byte of number of Lines

046

Y(L)

Least significant byte of number of Lines

047

X(H)

Most significant byte of number of Columns

048

X(L)

Least significant byte of number of Columns

049

Nf

Number of Components in a frame

04A

C(1)

ID of the first Component

04B

H(1), V(1)

Sampling ratio factors of the first Component

04C

Tq(1)

Quantization table ID number of the first Component

••

•

05F

C(8)

ID number of the eighth Component

060

H(8), V(8)

Sampling ratio factors of the eighth Component

061

Tq(8)

Quantization table ID number of the eighth Component

062

Reserved

•

•

•

079

Reserved

07A

SOS[FF]

Start of the first/fifth scan. There are four groups, 16-bytes each, one for each scan. Only the first SOS is used

in the decoding mode. In the case of multiple SOS markers in the compressed file, the old SOS is over written

with the new. Note that the example shown here is for a scan consisting of four components. If there are fewer

components the length of the segment will be shorter, and the fixed values [00, 3F, 00] at the end of this

segment will be at lower addresses.

07B

SOS[DA]

07C

LEN(H)

07D

LEN(L)

35

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