High Efficient Bandwidth Compression Algorithm For Audio Signal

High quality and low bit-rate have been the targets of audio coding. High frequency reconstruction technology being developed in recent years can be used to achieve the goal of low bit-rate coding while ensuring higher quality. So it is significant to do some research work in this area.A novel high frequency reconstruction technology-High Frequency Residue Replication (HFRR) algorithm is studied in the dissertation. By using the correlation property between high-frequency and low-frequency components, the proposed scheme is able to reconstruct the high-frequency components very similar to that of the original signals, only with the low-frequency components of the original and a few additional parameters reflecting the features of the high-frequency signals. In the dissertation, the modified strategies for HFRR are proposed and applied to three different compression frameworks, i.e. frequency domain residual based, time domain residual based and original spectral band based respectively. Testing and evaluating results have shown that all of the three design algorithms can achieve the higher band compression ratio for audio and speech signals in lower bit rates.More research work may be conducted to further improve the compression and quality. since the frequency compression and extension have already shown their potential advantages.