硬件资源消耗少的IMDCT分解算法

Hardware-Efficient Decomposition Algorithm for IMDCT Computation

提出一种新的改进离散余弦反变换(IMDCT)分解算法,把变换长度为N点的IMDCT分解为一对N/4点的IV-型离散余弦变换(DCT-IV/DCT-IV)。该变换的实现可以共享部分资源,从而减少所需的硬件。与已有的一些IMDCT快速算法相比,新的分解算法计算效率提高了3倍;硬件实现减少了1个锁存器(20%)、4个加法器(44%)和3个乘法器(50%)。设计相应的IMDCT硬件加速器并应用于AC-3音频的实时解码,验证了该算法的实用性。

A new decomposition algorithm for inverse modified discrete cosine transform（IMDCT） computation is presented.The algorithm converses an N-point IMDCT to a pair of N/4-point type-IV discrete cosine transforms（DCT-IV/DCT-IV）.Due to resource sharing,the implementation of DCT/DCT is hardware-efficient.Comparing with some well-known IMDCT algorithms,the proposed algorithm has higher computational efficiency（3 times higher） and requires 1 latch（20%）,4 adders（44%） and 3 multipliers（50%） less.To verify the proposed fast algorithm,a hardware accelerator based on the algorithm is designed and applied to the decoding of an AC-3 audio.The experimental results demonstrate that the AC-3 audio can be decoded in real time and therefore verify the practicability of the decomposition algorithm.