EAGLE
PRELIMINARY
Ver 1.3
3.29
JPEG Decoder
Features
Decodes 1 640x480 4:2:0 format frame (lena image) in 35ms (using GDMA)
ISO 10918-2 Base line JPEG Decoder
Only supports Typical Huffman table defined in annex K of standard.
Supports YCbCr 4:2:2 Format
Support YCbCr 4:2:0 format
Maximum Resolution is 1024x1024
Decode the image which has width of 32 multiple and height of 8 multiple(4:2:2 format) or 16 multiple(4:2:0 format)
Block Diagram
Figure 3-60 JPEG Decoder Block Diagram
There are three 64x32 FIFOs in JPEG Decoder for storing JPEG Image data , decompressed DATA (YCbCr) and address
informant of MCU(Minimum Code Unit). The FIFO’s level is decided by setting value of JDFCON Register[6:0]
During the operation of JPEG decoder, FIFO Fill Request IRQ (Level Trigger) is triggered in decoder by JPEG Image data
Request. IRQ is held when data fills the FIFO up to the FIFO level set in JDCTRL register and cleared automatically when
the number of DATA in FIFO is more than the level of FIFO. IRQ reoccurs when number of data in FIFO is below the FIFO
level.
JPEG Decoder ends the IRQ that indicates end of image decoding when JPEG Image EOI (End Of Image) Maker is decoded.
This IRQ is an Interrupt source of JPEG Image Capturer, and JPEG Image Capturer uses this interrupt source to generate
JPEG Image Capture IRQ (JICCIRQ) when the last MCU data is stored into Memory. JICIRQ is held until user clears the
JPEG Decoder End IRQ by software
Beijing Peak Microtech Co.Ltd.
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