STV0974 datasheet(13/69 Pages) STMICROELECTRONICS

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Functional description

STV0974

13/61

4.4

Video compression (VC)

Real time video compression permits a frame rate of 30 frame/s in any mode at VGA.

The JPEG compression engine is a standard baseline sequential JPEG encoder

[2].

The compression ratio can be modified by applying a multiplication factor on the quantization table.

The quantization table can be scaled from a factor of 1/8 to a factor of 8.

The STV0974 video compression block includes a baseline DCT JPEG encoder compliant with

ISO DIS 10918-1.

The JPEG encoder has the following characteristics:

● baseline sequential DCT based encoder

● YUV 422 encoding only

● up to VGA image size

● scalable quantization table

● standard quantization table

● standard Huffman coder

The encoder top level block diagram is presented in

Figure 3.

The input data is a YUV 422 8-bit data stream in raster order. The output data is a baseline JPEG

data stream.

Figure 3: Encoder top level block diagram

Raster

to block

converter

Discrete

Cosine

transform

ZigZag

transform

Entropy

coder

Quantize

STV0974 Datasheet(PDF) 13 Page - STMicroelectronics