A Comparison Of AVS2 Audio With MP3 And Implementation Of AVS2 Audio Recording And Playing

AVS2 (Audioe and Video Codec Standard) is the standard which is work out by our country independently. Our country holds the independent intellectual property rights. The AVS2 standard's lossy audio section contains the first generation AVS lossy audio coding. It can achieve high-fidelity audio coding method and high-fidelity audio decoding method. The coding speed of AVS is two to three times higher than MPEG-2. AVS2 audio is currently focused on high-definition television applications and achieving 5.1 surround sound high-fidelity coding. These characteristics of AVS2 bring great potential for its development.Although there is an initial version of reference code forAVS2 lossy audio coding, there is no available AVS2 audio code development tool library or the actual application system. In addition, the reference code can only achieve the conversion between WAV files and AVS2 audio files.Based on the quantitative analysis of AVS2 lossy audio coding performance(compression rate and distortion), the AVS2 reference code is analyzed in detail in this paper.What's more, an AVS2 audio file recording program based on Android and an AVS2 audio file real-time playback program based on the WINDOWS platform are realized by C language and multi-thread design. The work of this paper has practical value for the popularization and practical application of AVS2 audio codec technology.Because the performance of AVS2 lossy audio encoding can't be retrieved in the public literature. In this paper, we first compute and compare the compression rates of AVS2 and MP3. The results show that the compression ratio of ASV2 is much lower than that of MP3,and the compression effect is better than MP3 5.7 times. Then, we make a quantitative analysis by using the distortion function from the perspective of information theory and signal processing. The average distortion of AVS2 is less than MP3 about 4%. So AVS2 audio makes a great upgrade in compression at the cost of a small reduction in audio signal quality.Combined with the above quantitative analysis on AVS2 lossy audio, the use of AVS2 audio instead of MP3 and other formats to achieve mobile phone call recording can save a lot of storage under the premise of small quality loss. In this paper, based on the analysis of AVS2 lossy audio coding algorithm reference code, the coding algorithm is transplanted from Windows platform to the Android platform and an AVS2 audio file recording based on Android is realized combined with the recording function.At the end of this paper, we describe the design and implementation of AVS2 audio file player based on WINDOWS platform in detail. Then we transform the single-threaded decoding program for multi-threaded through the the establishment of memory buffer and the introduction of WINDOWS multi-threaded library. The decoded audio signal is converted from WAV file to the playback buffer. The aim is to lay the foundation for further implementation of the generic third-party AVS2 audio decoding core library.This article is divided into five chapters. Chapter 1 summarizes the research background. Then it introduces some major digital audio codec standard, and describes significance of studying AVS2 audio and the content and structure of this article. Chapter 2 compares the module information and frame structure of AVS1 and AVS2 audio codec standard. Then it introduces storage structure of AVS2 file, especially the header information in detail. Chapter 3 makes a comparison between AVS2 and MP3 audio codec algorithm. It calculates the compression ratio and similarity and draws a conclusion according to the three indicators. Chapter 4 introduces techniques and tools for transplanting the encoding algorithm and analyzes the original AVS2 audio encoding algorithm for subsequent modification and use. In this chapter, I transplant the AVS2 encoder from windows to Android, and extend its function by adding the recording process. Finally the AVS2 recording and encoding system has finished on the Android platform. Chapter 5 focuses on the application of AVS2 decoding algorithm. A real-time playing system is put forward. It firstly introduces AVS2 audio decoding process and segments the original decoding process.Then it takes out and reseals the process of decoding each frame. Finally, it controls the decoding process of each frame and playing the decoded data by multi-thread. There are two threads. The producer thread is for decoding, and the consumer thread is for playing.