摘要
中 文 摘 要 近幾年來，由於數位通訊的快速進展，這個世界已經正式邁入電腦科學發達與網際網路普及的數位時代。數位資料的取得及下載變的非常方便，然而科技的進步雖然增進了工作的效率，再另一方面也使得盜版及不法使用更加容易。因此多媒體智慧財產的保護便得相當重要。數位浮水印或是資訊隱藏技術的研究與發展即為了保護擁有者或著作者的版權。另外，音樂信號擁有特殊的性質，速度以及拍子的演算法也是一項有趣的研究。 此論文呈現了兩個數位音訊隱藏技術及一個音樂速度的演算法。這兩種技術是利用相位來做音訊隱藏。第一個方式利用到波的干涉現象，如果兩波同相位，則會有建設性干涉；反相，則有破壞性干涉。可以利用到這種性質來做音訊以及光學的隱藏，解碼方式不需要一定要利用電腦，也可經由人類觀察。另外一個編碼方式則是利用參考點的相位來修改相位值以達到隱藏信號的目的。這兩種加密方式都不會讓人起疑，且在編碼以及解碼都很簡單。 音樂信號不同於一般的音訊信號有獨特的性質。這些特性利如音高、節奏、調號等。我們以音樂角度切入介紹以及對應的演算法。接著我們呈現Scheirer提出的速度以及拍子演算法，以及和人打拍子的結果比較。
並列摘要
Abstract In the last few years, with the fast growing digital communication, the world has evolved into a multimedia age with booming Internet connectivity. It has become very easy to obtain and download digital data. However, easy access and duplication have posed serious problem of piracy in media distribution. The watermarking and data hiding techniques are researched and developed to protect the copyright of owner and the author. In addition, musical signal has its own special property, tempo and beat algorithm is also an interesting researching. Two data hiding in audio schemes and one tempo and beat algorithm are presented in this thesis. The hiding schemes are based on phase. First scheme uses the property of wave interference, consider two waves are in phase, they will have constructive interference; out of phase, then destructive interference. We can use this property to hiding data in audio and optical. The decryption may not necessary need computer but can accomplished by human observation as well. The other encryption method uses reference phase to modify the phase value to hide the data. These two methods are not suspicious and are easy in encoding and decoding. Musical signal is not like general audio, it has its unique property. These properties, like pitch, rhythm, and key etc. We present the property with the viewpoint from music and its corresponding searching algorithm. Then we focus on tempo and beat analysis and implement Scheirer’s algorithm and compare the result with human tapping.
參考文獻
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