Research Of Lossless Audio Encoding Algorithm

With the rapid improvement of audio compression technology and people’s demand of higher quality audio, there need to be more channels and more complex algorithms in the audio coding area. No longer satisfied with auditory lossless, we requires truely lossless audio. Besides, some particular usage such as data archive needs lossless coding,which helps improving the lossless conding technology.In this thesis, an embedded audio encoder is developed based on Professional Audio Development Kit (PADK), which is designed by Lyrtech. This thesis discusses the theory of lossless coding and the implement of FLAC encoder on PADK. First this thesis introduces two lossless coding standards,FLAC and AVS lossless, and then analyzese the two standards’s key modules:LPC and entropy encoding. Then based on the encoding effectivity and computing complexity of the two ways to choose LPC order, we choose the low complexity way. By optimizing entropy encoding, the FLAC encoding complexity becomes lower.After that, a brief introduction on the hardware feature of PADK and DSP/BIOS operating system is made, followed by embedded C optimizing methods.By using the C optimizing methods we accomplished a low complexity FLAC encoder. Through the transplanting of the audio algorithm on PADK and the task scheduling under DSP/BIOS operating system, an embedded audio encoder is implemented on this platform. Currently, this encoder can sample PCM in real time and accomplish FLAC encoding algorithm without delay.