本文選題：AVS + 幀間模式選擇��； 參考：《西安電子科技大學(xué)》2014年碩士論文

【摘要】：邁進新世紀(jì),為了有效地解決海量視頻數(shù)據(jù)在傳輸與存儲中所帶來的困難,視頻壓縮技術(shù)得到了迅猛地發(fā)展。AVS(Audio Video coding Standard)作為我國獨立設(shè)計與制定的視頻編解碼標(biāo)準(zhǔn),它的出現(xiàn)打破了國外在視頻編解碼領(lǐng)域的壟斷地位。在AVS中應(yīng)用了很多創(chuàng)新技術(shù),使得它擁有很好的壓縮性能。然而它優(yōu)越的壓縮性能是用犧牲復(fù)雜度來換取的。因此,在不影響視頻主客觀質(zhì)量的條件下,怎樣去降低AVS的復(fù)雜度是當(dāng)前一個研究熱點。本文對開源x AVS編碼器進行研究,其研究目的是從算法和指令優(yōu)化兩個方面在原始的編碼器基礎(chǔ)上進一步提升編碼速率。針對這一目的,本文完成的工作主要包括了以下的內(nèi)容:首先,根據(jù)整數(shù)變換與量化的特點,結(jié)合全零塊預(yù)判決的本質(zhì)思想,推導(dǎo)出了基于變換量化特點的全零塊預(yù)判決條件。同時依據(jù)圖像殘差系數(shù)服從拉普拉斯統(tǒng)計分布的理論,推導(dǎo)出了基于拉普拉斯統(tǒng)計模型的全零塊預(yù)判決條件。結(jié)合上述所得到的兩個預(yù)判決條件,給出了一種基于混合模型的全零塊預(yù)判決算法。實驗結(jié)果表明此算法相比于已有的算法全零塊檢出率平均提高20%左右。然后,在基于混合模型的全零塊預(yù)判決算法基礎(chǔ)上,給出了一種基于全零塊幀間模式選擇提早結(jié)束算法。此算法能夠提前終止幀間模式選擇,跳過變換與量化操作,節(jié)省編碼時間。實驗結(jié)果表明此算法編碼速率在原始編碼器的基礎(chǔ)上平均提高了27%左右,而峰值信噪比平均下降僅為0.05dB,傳輸碼率平均上升僅為2.04%。最后,分析并統(tǒng)計了編碼器各個關(guān)鍵模塊耗時的情況。在支持AVX(Advanced Vector Extensions)多媒體指令集的平臺上,分別對耗時較大和密集計算的模塊進行優(yōu)化,如計算SAD(Sum of Absolute Difference)、分像素插值、幀內(nèi)預(yù)測以及變換量化等。與C代碼模塊相比,指令優(yōu)化后的模塊實現(xiàn)了單指令多數(shù)據(jù)流的處理方式。通過采用1080P視頻序列測試,與原始的編碼器進行性能比較,使用峰值信噪比、碼率以及編碼速率三個指標(biāo)對比分析優(yōu)化性能,其結(jié)果表明在峰值信噪比和傳輸碼率保持不變的情況下,指令優(yōu)化后的編碼速率要比原始的編碼器平均提高3.11倍。結(jié)合AVX指令集與基于全零塊幀間模式選擇提早結(jié)束算法,實驗結(jié)果表明優(yōu)化后的編碼速率在原始編碼器的基礎(chǔ)上平均提高了3.37倍。
[Abstract]:In the new century, in order to effectively solve the difficulties caused by the mass video data transmission and storage, the video compression technology has been developed rapidly. AVSU Audio Video coding Standard) is a video coding and decoding standard designed and formulated independently in China. Its appearance broke the foreign monopoly in the field of video coding and decoding. Many innovative technologies have been applied in AVS, which makes it have good compression performance. However, its superior compression performance is achieved at the expense of complexity. Therefore, how to reduce the complexity of AVS without affecting the subjective and objective quality of video is a hot topic. In this paper, the open source x AVS encoder is studied. The purpose of the research is to improve the coding rate on the basis of the original encoder from two aspects: algorithm and instruction optimization. For this purpose, the work accomplished in this paper mainly includes the following contents: firstly, according to the characteristics of integer transformation and quantization, combined with the essential idea of all-zero block pre-decision, the condition of all-zero-block pre-decision based on the characteristic of transform quantization is derived. At the same time, according to the theory of image residual coefficient from Laplacian statistical distribution, the full zero block pre-decision condition based on Laplacian statistical model is derived. Combined with the above two pre-decision conditions, an all-zero-block pre-decision algorithm based on mixed model is presented. The experimental results show that the detection rate of this algorithm is about 20% higher than that of the existing algorithms. Then, on the basis of the all-zero block pre-decision algorithm based on hybrid model, an early termination algorithm based on all-zero-block inter-frame mode selection is proposed. This algorithm can terminate the mode selection between frames ahead of time, skip the operation of transformation and quantization, and save coding time. The experimental results show that the coding rate of the proposed algorithm is increased by about 27% on the basis of the original encoder, while the peak signal-to-noise ratio (PSNR) is only 0.05dB, and the average transmission rate is only 2.04b. Finally, the time consuming of each key module of encoder is analyzed and counted. On the platform that supports AVX(Advanced Vector extensions multimedia instruction set, the modules which are time-consuming and intensive are optimized, such as computing SAD(Sum of Absolute difference, sub-pixel interpolation, intra-frame prediction and transform quantization, etc. Compared with C code module, the optimized instruction module realizes the processing of single instruction and multi data flow. By using 1080P video sequence test, compared with the original encoder, using the peak signal to noise ratio (PSNR), bit rate and coding rate to compare and analyze the optimized performance. The results show that the optimized coding rate is 3.11 times higher than that of the original encoder under the condition that the PSNR and the transmission rate remain the same. Combining the AVX instruction set with the early termination algorithm based on the all-zero block inter-frame mode, the experimental results show that the optimized coding rate is 3.37 times higher than that of the original encoder.
【學(xué)位授予單位】：西安電子科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TN919.81

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本文編號：1886403