| 摘要: | 被稱為H.264/AVC 的國際最新影像編碼標準，是由國際電信聯盟遠程通信標準化組所提出的H.264和國際標準化組織/國際電工委員會所提案的MPEG-4 part 10 advanced video coding (AVC) 兩者合併而來的。與之前的影像編碼標準如MPEG-2及 H.263相比，H.264/AVC在相同位元率下之影像品質獲得大幅改善，H.264/AVC 利用 RDO 技術來審核所有可能的畫面間與畫面內模式，以求達到最佳的編碼效能。然而，也正因為此項技術的使用，使得H.264/AVC的計算複雜度遠勝於現存的任何一種影像編碼標準。但由於影像編碼標準如MPEG-2及H.263的應用已經普及於各種無線網路及電視廣播及多媒體裝置，遂使轉換編碼技術愈形重要。所謂的影像轉換編碼是指將已編碼的影像序列轉換成另一種不同的格式，例如位元速率、畫面速率或是壓縮標準等都是可變換的特性。本計劃主要在探討以最快的速度執行從MPEG/H.263/H.264 至H.264/AVC之轉換編碼的動作並維持一定的影像品質。要達成降低位元率的轉換編碼目標，最簡單的作法是對原始的視訊串流解碼後，進行完全再次編碼之複雜型轉換編碼法，但是這種方法的運算複雜度太高，所耗費的時間過多。因此原始視訊串流中資訊再利用的演算法便因應而生，為的正是運算成本能大幅降低。本子計畫擬在三年內研究並實現一套適用於異質無線網路系統(如Wi-Fi, WiMAX, 3G/3.5G/4G 及LTE 無線網路系統) 之即時性且快速 MPEG/H.263/H.264/AVC至H.264/AVC之轉換編碼技術以降低其計算複雜度並且維持其轉換編碼影像品質，其中包括三個部份，第一個部份主要著重於H.264/AVC至 H.264/AVC在不同位元速率、解析度及畫面速率之轉換編碼技術。接著第二年及第三年我們將探討MPEG-x/H.263至H.264/AVC之轉換編碼技術。為了達到即時處理的應用，我們探討的主題包括轉換編碼技術中畫面間快速模式決策之研究、快速整數點、非整數點移動估計之研究、多幅參考畫面的移動估計以及畫面內快速模式決策之研究。第三年我們亦將建立起一測試平台，將整合MPEG-X/H.263/H.264/AVC至 H.264/AVC之轉換編碼技術，測試並加以修正各種快速演算法則，使其轉換編碼性能及編碼時間達到最佳化。並將影像透過即時性快速轉換編碼器編碼再經過異質無線網路系統平台來傳送影像，測試以及修正各種快速演算法，使其有最佳的影像品質及即時性傳輸。最後將本系統的整體效果與其他子計劃作整合，並將相關研究成果發表於知名期刊。 ; The newest international video-coding standard, referred to as H.264/AVC, has been approved by ITU-T as recommendation H.264 and by ISO/IEC as the MPEG-4 part 10 advanced video coding (AVC) international standard. The emerging H.264/AVC momentously achieves better performance in both PSNR and visual quality at the same bit rate compared with prior video coding standards such as MPEG-2 and H.263. Because of its superior performance, H.264/AVC has been used for a wide range of applications in wireless network, broadcasting and storage systems. To whatever extent, the MPEG-2 video or H.263 video has been widely used in today’s digital video applications. Transcoding is one key technology that provides such interoperability between various systems and devices. Video transcoding is defined as the conversion of one coded video sequence to another, which includes a wide range of characteristics such as bit-rate, frame rate, coding standards, etc. The most straightforward way to succeed transcoding process is to decode the video stream and re-encode the reconstructed video sequence at a new rate or coding standard. The fully decoding and re-encoding process, referred to as complex cascaded pixel domain transcoding (CCPDT), is quite involved and time consuming. Reusing information enclosing the original incoming video stream reduces computational complexity. To reduce the computation cost and maintain coding performance during transcoding, in this three-year’s project we will investigate and develop efficient and fast algorithms for MPEG/H.263/H.264/AVC to H.264/AVC transcoding for heterogeneous wireless network systems (such as Wi-Fi, WiMAX, 3G as well as LTE). In the first year we will investigate and develop many fast and efficient methods for H.264/AVC to H.264/AVC intra-frame and inter-frame transcodings at a new bit rate, new frame rate and/or different coding standards. Both efficient intra-frame and inter-frame transcodings for H.264/AVC to H.264/AVC will be studied. In the second year, we will focus on the efficient and fast MPEG-2/H.263 to H.264/AVC transcoding algorithms, including intra-frame and inter-frame transcoding. Finally we will concentrate on the integration of MPEG/H.263/H.264 to H.264 transcoding and integrate with the other projects, and design a H.264/AVC transcoding system suitable for heterogeneous wireless network system. ; 研究期間 9808 ~ 9907 |
