臺灣博碩士論文加值系統

Thanks to the advance of technologies with each passing day, the blooming variety of mobile information products is now prominent. Multimedia entertainment, such as digital music, games, videos, enriches people’s lives. In November 2007 Internet giant Google released Android mobile operating system. Its open source model not only empowers a lot of companies to accelerate the speed to announce new products into the market, but also enables their products with more innovative features.

As far as the multimedia standard is concerned, H.264 is the state-of-the-art compression technique and with an outstanding performance in terms of video quality and compression ratio. Android supports this media format, but its multimedia framework is designed as single-core architecture. Dealing with a large number of multimedia computing often results in system overload hence reduces overall performance. In order to make good use of the advantages of multi-core architecture, an issue arises from the aforementioned descriptions. That is, How to customize such a diverse and complex Android system becomes interesting but challenging at the same time.

This thesis adopts the PAC Duo SoC evaluation platform, developed by the SoC Technology Center at Industrial Technology Research Institute in Taiwan. This platform features low-power and high-performance DSP cores for multimedia applications. We conduct a case study of the H.264 encoder under the Android system, trying to parallelize the multimedia workload, in a software design manner, from the perspective of flow control and/or data flow. To achieve load balancing and increase execution efficiency, we take the multimedia computing away from the MPU and assign the workload to the PAC DSP.

A comparison to the performance of the original and the modified architecture is presented at the end of this thesis. We also propose the H.264 photography application to verify the integrity and functionality of our system.

　　隨著科技的日新月異，行動資訊產品的多元化發展已經是不可避免的趨勢，音樂、遊戲、影片等多媒體娛樂，豐富了人們的行動生活。網路巨擘Google於2007年11月發布Android行動作業系統，透過開放原始碼的模式，使得許多的公司能以此作為基礎，加快產品上市時間，更可以為自家產品提出更多新奇創新的功能。

　　就多媒體技術標準來說，H.264無論在是畫質、壓縮比上皆有相當傑出的表現，是當今主流的影像編碼技術。Android系統本身支援此多媒體格式，但所採用的OpenCORE多媒體框架為單核心架構，在處理大量多媒體資料運算上，往往造成系統超載，降低整體表現。上述所衍生出來的議題，即是如何針對Android這樣多元複雜的系統進行客製化，以期能夠善用多核心架構的優勢。

　　本篇論文採用工研院晶片中心所自主研發的PAC Duo EVB異質多核心實驗平台。此平台具有多媒體應用的數位訊號處理器，以低功耗與高效能為其特色。並以Android系統下的H.264編碼器為例，從軟體設計的角度，針對控制流程(Function partition)與資料層面(Data partition)來進行平行化處理，將多媒體運算從MPU當中抽出，分配到其中一顆PAC DSP當中，使負載能平衡，進而提高執行效率。本文最後比較以原始架構與修改後的執行效能，並且提出H.264攝影技術為其應用，作為驗證系統功能完整性與正確性之實際案例。

摘要 i
Abstract ii
致謝 iv
目錄 v
圖片目錄 vii
表格目錄 ix
Chapter 1 Introduction 1
1.1 Background 1
1.2 Motivation 2
1.3 Organization of This Thesis 2
Chapter 2 Preliminaries and Proposed Methodology 4
2.1 Android 4
2.2 H.264/AVC 6
2.2.1 Introduction 6
2.2.2 Profile 7
2.2.3 Structure of H.264/AVC 10
2.3 OpenMAX 11
2.4 OpenCORE 15
2.5 Multi-Core SoC Platform 19
2.6 Proposed Methodology 23
Chapter 3 Design and Implementation 24
3.1 Execution Flow 24
3.2 PAC DSP H.264 Encoder API 29
3.3 Android Camera HAL 31
3.4 Application 33
Chapter 4 Experimentation and Statistical Analysis 36
4.1 Experimental Environment 36
4.2 Performance Evaluation 37
Chapter 5 Conclusion and Future Work 42
Chapter 6 Reference 43
Appendix A 45

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