本文選題：實(shí)時(shí)視頻傳輸 + 碼率動(dòng)態(tài)調(diào)整��； 參考：《重慶大學(xué)》2014年碩士論文

【摘要】：在3G網(wǎng)絡(luò)中傳輸實(shí)時(shí)視頻是一種典型的應(yīng)用。相比于其他業(yè)務(wù)，視頻信息的數(shù)據(jù)量大，傳輸之前必須經(jīng)過壓縮。目前最常用的壓縮標(biāo)準(zhǔn)為H.264，經(jīng)過H.264壓縮后的視頻流可以在3G網(wǎng)絡(luò)信道上獲得較好的傳輸效果。但是由于3G網(wǎng)絡(luò)帶寬不穩(wěn)定，且抖動(dòng)明顯，因此，如何根據(jù)3G網(wǎng)絡(luò)帶寬變化情況，動(dòng)態(tài)調(diào)整H.264碼率控制策略，以取得更佳的視頻傳輸效果，獲得更好的用戶體驗(yàn)，是移動(dòng)網(wǎng)絡(luò)視頻傳輸技術(shù)中值得研究的一個(gè)問題。 論文工作圍繞實(shí)時(shí)視頻通信中發(fā)送端可能獲取的網(wǎng)絡(luò)狀態(tài)信息，從網(wǎng)絡(luò)帶寬預(yù)測(cè)的角度來動(dòng)態(tài)調(diào)節(jié)視頻碼率，并根據(jù)幀的重要程度不同，實(shí)施有選擇的丟幀策略，以期取得更好的視頻傳輸體驗(yàn)。論文主要開展了以下一些工作： ①分析了實(shí)時(shí)視頻通信中視頻發(fā)送端可能感知的網(wǎng)絡(luò)帶寬參數(shù)，建立一種視頻編碼碼率控制的模型。該模型根據(jù)發(fā)送端緩沖區(qū)比特流的大小，預(yù)期的網(wǎng)絡(luò)帶寬和變化趨勢(shì)，來調(diào)整和控制相應(yīng)的H.264碼率控制指標(biāo)。 ②在以上模型基礎(chǔ)上，提出了針對(duì)模型中不同處理階段的優(yōu)化策略。針對(duì)編碼碼率頻繁切換對(duì)移動(dòng)終端帶來的處理開銷問題，實(shí)施碼率分等級(jí)變換方式；通過設(shè)定和監(jiān)測(cè)相關(guān)參數(shù)閾值，實(shí)施發(fā)送緩沖區(qū)管理策略；根據(jù)H.264編碼后的幀重要性不同，在3G網(wǎng)絡(luò)出現(xiàn)擁塞情況時(shí)，根據(jù)幀的重要性不同而采取優(yōu)先丟棄非關(guān)鍵幀的幀丟棄策略。 ③采用JM平臺(tái)和VCEG-N80離線環(huán)境，開展了仿真實(shí)驗(yàn)，以檢驗(yàn)所提出方法在網(wǎng)絡(luò)帶寬預(yù)測(cè)方面的有效性。通過測(cè)量丟包率計(jì)算PSNR值的實(shí)驗(yàn)，，比較了傳統(tǒng)傳輸模式與論文改進(jìn)模式下實(shí)時(shí)視頻傳輸效果的不同，驗(yàn)證了論文所提出改進(jìn)方法的有效性。
[Abstract]:It is a typical application to transmit real-time video in 3G network. Compared with other services, video information has a large amount of data and must be compressed before it is transmitted. The most commonly used compression standard is H.264. The video stream compressed by H.264 can achieve better transmission effect in 3G network channel. However, because the bandwidth of 3G network is unstable and jitter is obvious, how to dynamically adjust H.264 rate control strategy according to the change of 3G network bandwidth, in order to obtain better video transmission effect and better user experience, It is a problem worth studying in the video transmission technology of mobile network. This paper focuses on the network state information that may be acquired by the sender in real-time video communication, dynamically adjusts the video bit rate from the point of network bandwidth prediction, and implements a selective frame dropping strategy according to the importance of the frame. In order to achieve a better video transmission experience. The main work of this paper is as follows: 1 the network bandwidth parameters that the video sender may perceive in real-time video communication are analyzed and a video coding rate control model is established. The model adjusts and controls the corresponding H.264 rate control index according to the size of the buffer bit stream, the expected network bandwidth and the changing trend. An optimization strategy for different processing stages of the model is proposed. In order to solve the problem of processing overhead brought by frequent code rate switching to mobile terminal, the rate hierarchical transformation is implemented, and the transmission buffer management strategy is implemented by setting and monitoring the threshold of relevant parameters. According to the different importance of H. 264 encoded frame, When there is congestion in 3G network, according to the importance of frame, the strategy of dropping non-key frame first is adopted. 3 the simulation experiment is carried out using JM platform and VCEG-N80 off-line environment. The effectiveness of the proposed method in network bandwidth prediction is verified. Through the experiment of calculating PSNR value by measuring the packet loss rate, the differences between the traditional transmission mode and the improved mode of real-time video transmission are compared, and the effectiveness of the improved method proposed in this paper is verified.
【學(xué)位授予單位】：重慶大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TN919.8

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