about the 8x8 macro block for JPEG

[ys82]

jpeg macro block

I want to design a asic block for JPEG encoder, But I'm confused with the scan of JPEG standard:
"input block by block from left to right, and block-row by block-row from top to bottom".

But images are usually captured a line at a time, the cmos sensor output pixel data line by line, for encoder the pixel data from coms sensor, I need to store 8 or more line image data , so The buffer will be very large for 1.3 megapixel....

Can I encoder pixel data line by line, when receive 64 pixel data form one line, the jpeg encoder will start to compress these data..........If I implement hardware like that , can I still use the Quantization/huffman tables which recommend by ITU-T.81 ??? by the way, the softeware jpeg decoder is designed by ourselves ..

I really need your suggestions !!
many thanks !

 

[TurboPC]

jpeg macrobloc

Not really. The DCT works in horizontal and vertical directions on the 8x8 block. It won't work if you do it horizontally only. It sucks, but you need those 8 lines of delay.

 

[Ralph80]

In JPEG, the DCT is two-dimensional. In results, it concentrates non-zero coefficients in top left corner. It is kind of spectrum for the image. There is no possibility to make DCT on 64 in line pixels, because blocks are organized to MCUs. See JPEG description . Maybe it helps You.

 

[rameshrai]

Jpeg or mpeg encoder uses DCT, zigzag scanner, huffman encoder in sequence see this article for full details
**broken link removed**