ADSP-BF707 JPEG Decoder Performace

Dear All, 

I am performing JPEG Decode operation with ADSP-BF707 processor. Decode operation takes longer than I expected.

I did the encode and decode operation on the same image as BF707. The processing times are as follows. (Image size 300x380 YUV420)

Encode time = 10.8ms

Decode time = 44.9ms

In performance tests on documents "KT-570 JPEG Decoder Product Specification" and "KT-571 JPEG Encoder Product Specification" , the difference between encode and decode times is not high.

for examle 

What is the cause of the problem?
How can I solve?
I would like your advice.