VLSI Design of a High-Speed and Area-Efficient JPEG2000 Encoder

Abstract

A high-speed VLSI design of an area-efficient JPEG2000 encoder is given. Recursive multilevel 2D discrete wavelet transform (DWT) architecture with dual buffers is proposed to reduce the wavelet coefficients memory to 1/4 tile size, prerate allocation is used to reduce the compressed code memory to 3/4 tile size. A highly pipelined and parallelism implementation of line-based 1-level DWT is proposed using two line-buffers in 5/3 wavelet type and its input speed is up to 2 samples/cycle; code block based address mapping in access wavelet coefficients memory, concurrent state variables generation and multiple parallel and pipeline coding methods are used in the bit plane encoder (BPE) which encodes on average at 40.5 M samples/s at 100 MHz with no memory used; the conditional two-symbol pipeline arithmetic encoder (AE) encodes at 1.3 symbols/cycle. Parallel units in BPE and buffer control between BPE and AE are optimally implemented with low cost without performance loss. Byte representation of rate-distortion slope used reaches a near optimal implementation of post-coding rate distortion in Tier2 with low cost. The compressed file generated by the encoder is fully compatible with ISO/IEC FCD15444-1. The encoder is verified on field-programmable gate array platform with a direct interface to digital video input with tile size 256 times 256 and code block size 32 times 16. The resulting input sampling rate is up to 58 M samples/s when Tier1 operates at 100 MHz. Difference of the peak signal-to-noise ratio of images compressed by our encoder and JasPer is less than 0.2 dB when the compression ratio is greater than 1 bps. Equivalent NAND2 gates synthesized are 90.6 K and on-chip RAM size is 626.75 kb. Unlike other designs the proposed design of JPEG2000 encoder has high compression quality as well as high speed and area-efficiency.