研究生: |
陳進旺 CHIN-WANG CHEN |
---|---|
論文名稱: |
應用AMDF演算法之音高點擷取方法 A Pitch Extration Method Based on the AMDF Algorithm |
指導教授: |
楊傳凱
Chuan-Kai Yang |
口試委員: |
羅乃維
Nai-Wei Lo 林伯慎 Bor-Shen Lin |
學位類別: |
碩士 Master |
系所名稱: |
管理學院 - 資訊管理系 Department of Information Management |
論文出版年: | 2007 |
畢業學年度: | 95 |
語文別: | 中文 |
論文頁數: | 45 |
中文關鍵詞: | 音高偵測 、音調 、基頻 |
外文關鍵詞: | AMDF, pitch detect, local minima, fundamental frequency |
相關次數: | 點閱:156 下載:1 |
分享至: |
查詢本校圖書館目錄 查詢臺灣博碩士論文知識加值系統 勘誤回報 |
AMDF音高偵測演算法最常被詬病的是常常會發生判斷錯誤之問題,因此各種不同的改良式演算法紛紛地被提出來,但大部分都是著眼於演算法之運算公式改良的議題,而其實在演算法運算以後,Local Minima音高點之取點方式也是一個決定所偵測音高準確性的重要步驟。
本論文提出一個在AMDF演算法後之音高點擷取方法,主要分為三個步驟:第一個步驟是將每個位移點經AMDF演算法所求出的值,取出所有的Local Minima點,並經一個Clipper機制將大於限定值的Local Minima點去掉;第二個步驟是將剩下的Local Minima點進行相鄰點之比對篩選,只保留AMDF值最小的Local Minima點;最後一個步驟就是由所剩下來的Local Minima音高點中找出它的基本週期,且在過程中所找出之基本週期誤差率要低於音階誤差率之限制。
利用此方法來作音高點的擷取,可以有效解決並改善傳統AMDF演算法的缺失,單純以Local Minima最小值來取點所造成之誤判情況,雖然在取點運算時會增加一些運算時間,但整體來看,在兼顧準確度與運算速度上仍然可以接受。
Average Magnitude Difference Function (AMDF) is a pitch detection algorithm that is known to often suffer from the problem of pitch misjudgments. Various algorithms have thus been proposed to address this problem. However, as most of these algorithms focus on how to improve the procedure of AMDF itself, we argue that extracting the Local Minima pitch points may also play a critical role on enhancing the pitch detection accuracy, after applying the original AMDF algorithm.
This paper proposed a pitch point extraction algorithm which improves over the traditional AMDF algorithm, and it consists of three steps. First, we apply the AMDF algorithm to calculate the value of each transformed point, locate all Local Minima points, and discard those points whose values are greater than a threshold. Second, we compare the remaining Local Minima points with their neighboring points and retain only the smallest values around the Local Minima points. Finally, we determine the Local Minima fundamental frequency, under the constraint that the fundamental frequency discrepancy rate must be lower than a pre-specified threshold determined from the chromatic scale discrepancy rate.
Compared with the original version of AMDF, which may erroneously determine the pitch from the smallest Local Minima point, this proposed method could offer more accurate results. In spite of the additional overheads due to the processing of Local Minima points, the resulting accuracy is improved, while the overall calculation time is still well acceptable.
[1] A.M. Kondoz, “Digital Speech Coding for Low Bit Rate Communications Systems”, WILEY publishers Since 1807, pp. 59 - 75
[2] Jyh-Shing Roger Jang, “Audio Signal Processing and Recognition”, (in Chinese) available at the links for on-line courses at the author's homepage at http://www.cs.nthu.edu.tw/~jang
[3] 李俊毅,“語音評分Speech Evaluation”,清華大學碩士論文,民國91年
[4] D. G. Childers, D. P. Skinner, R. C. Kemerait, “The Cepstrum: A Guide to Processing”, Proceedings of the IEEE, Vol. 65, Issue 10, Oct. 1977, pp. 1428 - 1443.
[5] T. W. Parks, J. D. Wise, “Maximun Likelihood Pitch Estimation”, Decision and Control including the 16th Symposium on Adaptive Processes and A Special Symposium on Fuzzy Set Theory and Applications, 1977 IEEE Conference on Vol. 16, Issue , Dec. 1977, pp. 1092 - 1095.
[6] W.B. Kleijn, K.K. Paliwal, “Speech Coding And Synthesis”, ELSEVIER Science B.V., pp. 503 – 505
[7] http://en.wikipedia.org/wiki/Vocal_range
[8] Yu-Min Zeng, Zhen-Yang Wu, Hai-Bin Liu, Lin Zhou, “Modified AMDF Pitch Detection Algorithm”, Machine Learning and Cybernetics, 2003 International Conference on Volume 1, Issue , 2-5 Nov. 2003 Page(s): 470 - 473 Vol.1
[9] Wenyao Zhang, Gang Xu, Yuguo Wang, “Pitch Estimation Based On Circular AMDF”, Acoustics, Speech, and Signal Processing, 2002. Proceedings. (ICASSP apos;02). IEEE International Conference on
Volume 1, Issue , 2002 Page(s): I-341 - I-344 vol.1
[10] 吳宗儒,“哼唱輸入以AMDF與ACF方法結合實作音高偵測”,政治大學資訊科學系Database Lab
[11] 葉佳慧,“Contented Based Music Retrieval by Notes or Rhythms”,清華大學碩士論文,民國90年
[12] http://en.wikipedia.org/wiki/Piano_key_frequencies
[13] http://cnx.org/content/m11714/latest/
[14] http://ccrma.stanford.edu/~pdelac/154/m154paper.htm
[15] http://en.wikipedia.org/wiki/Pitch_detection_algorithm