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dc.contributor.author李智勇en_US
dc.contributor.authorChih-Yung Leeen_US
dc.contributor.author杭學鳴en_US
dc.contributor.authorHsueh-Ming Hangen_US
dc.date.accessioned2014-12-12T02:12:05Z-
dc.date.available2014-12-12T02:12:05Z-
dc.date.issued1993en_US
dc.identifier.urihttp://140.113.39.130/cdrfb3/record/nctu/#NT820430005en_US
dc.identifier.urihttp://hdl.handle.net/11536/57999-
dc.description.abstractCCITT H.261 訂定了影音服務中影像傳送的解碼標準,其所使用的位元率 為 p * 64 kbits/s ,其中 p 的範圍是 1 到 30。在非常低的位元率, 例如 64 或 128 kbits/s 時,這有限的頻寬必須有效的利用,每張傳送 的影像才能達到可接受的品質。因此,在此情況下,適當的選擇編碼參數 及緩衝器控制是非常的重要。我們的研究,是從電信研究所提供的影像電 話原型開始;目標是希望改進該系統所產生的影像品質。畫質的提昇可分 為兩個方向:第一是加上圖框間編碼以改進編碼效益,其次是改良現有緩 衝器的控制方式。為此目地,我們曾探討在空間及時間上解析度的選擇問 題;在低位元率時,一般認為一個好的系統,至少應保持一最低限度的清 晰度,亦即,圖框率將會低。在實用的硬體限制考量下,我們提出的編碼 方式適於即時影像壓縮,並在影像電話系統上得到驗證。 CCITT H.261 describes the video decoding standard for trans- mitting the video signals of audiovisual services. At very low bit-rate, such as 64 and 128 kbits/s, the limited bandwidth must be effectively utilized to achieve an acceptable overall picture quality. Therefore, the proper selection of encoding parameters and/or the buffer control strategy becomes very critical. Our study starts from an H.261 videophone system originally designed by TL, Ministry of Communication. Our goal is to enhan- ce the compressed video quality produced by this system. There are two directions of improvement. One is adding additional ope- rations such as interframe coding to increase coding efficiency. The other is improving the quantizer/buffer control scheme of the current system. For this purpose, we investigate the trade- off between temporal and spatial resolutions. When bit-rate is extremely low, it is generally believed that a high performance codec should keep a minimum picture quality for every single picture. Hence, the frame rate should be lowered. Taking also into account of the hardware limitation, this proposed scheme is suitable for real-time video encoding, and has been proved on our experimental videophone system.zh_TW
dc.language.isoen_USen_US
dc.subject影像電話; 緩衝器控制。zh_TW
dc.subjectVideophone; Buffer Control.en_US
dc.title適用於影像電話之緩衝器控制及實作zh_TW
dc.titleA Practical Buffer Control Strategy for Videophone Systems and Its Implementationen_US
dc.typeThesisen_US
dc.contributor.department電子研究所zh_TW
Appears in Collections:Thesis