基于Android平台的音效系统设计与实现

Design and Implementation of an Audio Enhancement System Based on Android Platform

针对手机、平板电脑等便携式电子产品的小尺寸扬声器在低频重放能力、动态范围、频率响应、声场宽度等方面表现不佳的问题,开发了包括立体声增强、低音增强、音频均衡器、动态范围压缩等在内的一系列音效增强算法,统称为iSurround音效。在Android平台上,我们设计开发了一款支持MP3和WAV的音乐播放器,称为i Surround音乐播放器。首先,播放器对音频文件进行解码,获取原始的PCM流,然后对原始PCM数据进行音效增强处理,最后将处理后的PCM数据送入Android驱动层。iSurround音乐播放器中的音效增强算法采用32位定点C程序实现,运算速度较浮点程序有明显提升。

For small loudspeakers in mobile phones and other portable electronics have poor performance in terms of bass reproduction, dynamic range, frequency response and sound field width,we develop the iSurround audio effect that includes stereo enhancement, bass boost, audio equalizer and dynamic range compressor is developed to address those problems. In this paper, we develop a music player based on Android platform which supports WAV and MP3 format files. Moreover, the iSurround audio effect algorithm is integrated into the music player. Firstly, the MP3 or WAV format file is decoded to obtain the raw PCM data. Then, the PCM data are processed by the iSurround audio effect algorithm. Finally, the processed PCM data are sent to the driver layer of Android OS. Besides, we use 32 - bit fixed - point C program to implement the audio enhancement algorithms, whose computation speed has been improved significant- ly compared with the floating - point version.