基於H.264視訊編碼在畫面略過轉換下之區塊模式決定與移動向量預測

Abstract

近年來，許多應用如即時線上播放系統、視訊會議、手持式多媒體、網路媒體快速瀏覽等需求大量提升。使用者期望在有限的網路傳輸速率以及既有的硬體設備下，能夠接收高品質的視訊畫面；而系統開發者除了追求能將高畫質的視訊影片，能以較低的位元壓縮率傳輸外，尚能提供流暢地視訊快速播放閱覽的功能。 在這篇論文當中，我們提出了一個適用於H.264/AVC視訊壓縮編碼標準下，利用畫面省略的轉換編碼方式來降低傳輸位元大小以及所需的視訊壓縮時間。其中的議題包含在省略畫面的情形下如何解決區塊分割大小模式的決定、區塊移動向量計算方法。 由實驗的結果可知，我們所提出的方法相較於H.264/AVC畫面略過的壓縮以及其他方法，在維持一定的視訊品質之下，大量的縮減壓縮的時間，並亦能傳輸於在低位元傳輸率中。

In recent years, many multimedia applications such as real-time video streaming systems, videoconference, handheld media systems, and high-speed video browsing through networks are required. Users expect to receive high quality of video under limited network bandwidth and established hardware equipments. Oppositely, system providers pursue services of high video quality through low bit-rate transmission in order to reduce the cost and provide more services. In this thesis, we focus on a frame-skipping transcoding methods to reduce the bit-rate for H.264/AVC video coding. We have proposed block mode decision methods, motion vector composition methods for frame-skipping transcoding. Experimental results show that, compared with H.264/AVC and other algorithms, the proposed methods can save a lot of computational cost. The performance can be improved by maintaining visual quality at low bit-rate.