An Acceleration Method for Performing MPEG Audio Layer III Compression with DSP Part 2
The MPEG (Motion Picture Expert Group) audio compression standard provides a compression algorithm with high fidelity and high compression ratio.
In the ISO11172-3 standard, subband audio coding schemes with different complexity and performance are described to suit various high-quality digital audio applications. According to the different coding computational complexity and coding efficiency, it is divided into three standards: Layer I, Layer II and Layer III.
The MPEG audio standard was originally derived from draft algorithms that were divided into four types: ASPEC Audio Spectral Perceptual Entropy Coding (ASPEC), Masking Mode Universal Subband Integrated Coding, and MUSICAM Multiplexing (Audio Spectral Perceptual Entropy Coding). masking pattern). Subband Integrated Multiplexing and Coding), Subband ADPCM SB/ADPCM (Subband Adaptive Difference PCM). After a series of objective and subjective sound quality tests, taking into account sound quality at different bit rates, sensitivity to transmission bit errors, encoding/decoding complexity, and encoding/decoding delays and other factors, at a low bit rate of around 100 kbit/s, ASPEC and MUSICAM showed the best sound quality. At a low bit rate (64 kbit/s), ASPEC shows better sound quality, while MUSICAM is slightly better at encoding and decoding complexity and delay. Based on various ASPEC algorithms, MUSICAM is enhanced, which increases computational complexity, but obtains a better compression ratio and sound quality, which is the ISO11172-3 Audio Layer III standard.
