| Summary: | 碩士 === 國立交通大學 === 電子工程系所 === 95 === With the fast development of the audio systems, multi-channel audio systems are commonly used for consumer electronic products such as DVD audio and digital audio broadcasting services. The MPEG Surround is an efficient audio coding standard defined by the ISO/IEC MPEG (Moving Pictures Experts Groups) committee. It is able to compress the multi-channel audio signals at a very low bit-rate. In this thesis, we propose several methods to speed up the MPEG Surround implemented on a DSP platform.
We analyze the complexity of the MPEG Surround encoder and find that among all modules the filterbanks require the most operational cycles on DSP. Hence, we adopt and modify several fast algorithms based on type-IV DCT/DST and FFT for implementing the filterbanks. We also eliminate the unnecessary computation in the LFE (low frequency effect) channel. For the DSP implementation, we use a few DSP code acceleration techniques to speed up such as fixed-point arithmetic, L2 cache, intrinsic function, loop unrolling and DSP macro function. The experimental results show that the modified MPEG Surround encoder is about 500 times faster than the original version.
Furthermore, we implement the combination of the accelerated MPEG Surround encoder and the HEAAC encoder together, and simplify the structure by using the downsampled SQMF bank. Comparing to the original structure, the simplified encoder is about 1.8 times faster.
|
|---|
