基於OpenMAX(TM) DL之H.264解碼器在PACDSP數位訊號處理器上的實作與最佳化

Implementation and Optimization H.264 Decoder based on OpenMAX(TM) DL for PACDSP

林立浩(Li-HaoLin)

指導教授 ： 石維寬

國立清華大學/電機資訊學院/資訊工程學系/碩士(2007年)

摘要

隨著多媒體時代的來臨，以及IC產業的進步,新一代的PMP (Protable Media Player)功能越來越強大，在多媒體功能的要求上是不容置疑的，多媒體種類眾多，包括音樂/音效、語音、照片/圖片(靜態影像)、視訊(動態影像)、2D/3D動畫等。現今的的行動多媒體裝置大多具備幾項能力，一、支援H.264、MPEG-4、MP3、VC1、AAC這幾個目前較主流的影像和音訊編解碼標準，二、支援無線通訊標準，比如在手機平台上加入GSM、GPRS、3G或WiMAX等通訊標準。
上面這些技術需要多種處理能力及複雜的電路設計，如果個別來達到這些技術設計的話，勢必無法達到體積小、攜帶方便的目標。因此整合各種多媒體解碼能力的SOC被廣泛應用在行動多媒體裝置。也因為這樣所以一個行動多媒體裝
置需要程度上硬體及軟體的配合，在效能上以及省電要求上是很重要的兩個考慮議題。目前最受歡迎的PMP架構為多核心處理器，一顆MPU(Main Processor Unit)搭配一顆或多顆DSP(Digital Signal Processor) 。
OpenMAXTM為一套由Khronos組織發佈的統一標準，其中有兩個重要介面，分別是DL(Development Layer)層、IL(Integration Layer)層，主要的優點是透OpenMAXTM訂出的這兩個統一介面能夠讓使用者在處理多媒體編解碼上達到跨平台及加速底層硬體效能。
本篇論文目的主要是能在Dual Core平台上加速多媒體處理效能，實驗平台為工研院的PAC平台，主要會在PACISS模擬器下作測試，多媒體編解碼採用H.264解碼器。而H.264解碼器的實作上則遵循OpenMAXTM DL的標準，再自行設計出一套函式庫，此函式庫是用PACDSP Assembly程式語言實作演算法且經過最佳化，讓上層使用者能夠藉由呼叫設計出來的函式庫，更方便的與底層的PACDSP平台溝通，並且讓硬體效能發揮的更好。

關鍵字

林立浩 ； 數位訊號處理器 ； 石維寬 ； 多媒體編碼 ； 多媒體解碼 ； 多媒體

並列摘要

With the arrival of the multimedia, and the improvement of IC industry, the functions of the new generation PMP (portable Media Player) is becoming stronger and stronger. It is no doubt that the powerful functions of multimedia are expected. There are many kinds of multimedia, including music/sound effect, audio, picture (static image), video (dynamic image), 2D/3D animation, etc. The most mobile multimedia devices have several abilities. First, they support H.264, MPEG-4, MP3, VC1, and AAC which are the main stream of image and audio codec. Second, they support the standard of wireless communication, such as GSM, GPRS, 3G, or WiMAX on the cell-phone platform.

These technologies mentioned above need many kinds of process ability and more complicated design of circuit. If each of these technologies is designed individually, it is definitely impossible to reach the goals of small size and the portability. Thus SOC with integration ability is applied on the mobile media device extensively. However, because these devices need the cooperation on hardware and software, two important issues about efficiency and energy saving are worth of being considered. The most popular PMP architecture is multi-core processor that has one MPU (Main Processor Unit) plus one or more DSP (Digital Signal Processor).

OpenMAXTM is a unified standard released by Khronos group. There are two important interfaces. One is DL (Development Layer) and the other one is IL (Integration Layer). The major advantage is that these two interfaces can cross platforms and accelerate the performance of hardwares when the users and programmers process multimedia codec.

The main motivation of this thesis is to accelerate the performance of processing multimedia. The platform of the experiment was called PACDSP platform which was developed by ITRI. The testing was under the environment of PACISS simulator. The multimedia codec adopted H.264 decoder, which followed OpenMAXTM DL standard. Then the author designed one library by PACDSP assembly code and implemented the algorithm as well as optimization. Therefore, the upper users can call this designed library to communicate with the PACDSP hardware more conveniently.

並列關鍵字

H.264 ； OpenMAX ； PACDSP ； video ； LiHao ； OpenMAX DL

參考文獻

Advanced Video Coding (second edition)“Munich(DE), March 2004.

Decoder on General-Purpose Processors with Media Instructions“, Proceedings of SPIE -- Volume 5022, Image and Video Communications and Processing, May 2003.

[7] The Khronos Group In.“OpenMAXTM Integration Layer application programming Interface Specification“, Version 1.1, February 21, 2007.

SoC Technial Journal 004，April 2006.

[11]“OpenMAX Sample Code Release Note, OX000-BU-00000-r0p0-00bet0”, ARM, 2006.