MAXIMIZING AUDIOVISUAL QUALITY AT LOW BITRATES
MAXIMIZING AUDIOVISUAL QUALITY AT LOW BITRATES
复制标题
以低比特率最大化视听质量
DOI：
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发表时间：
2005
期刊：
影响因子：
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通讯作者：
C. Faller
中科院分区：
文献类型：
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作者：
S. Winkler;C. Faller
ABSTRA CTW对音频、纯音频和纯视频的质量评估进行了大量的主题实验。我们选择的内容和编码参数的比特率非常低，这是移动应用程序的典型特征。利用这些数据，我们探讨了视频编解码器和帧速率以及音频通道和采样率对质量的影响。最后，研究了分配给比特流中的音频和视频的比特之间的最优折衷f。国际IDEO质量(VQ)评估[15，16]已变得不那么容易建立，这从可供检索的出版物和产品的数量，以及V IDEO质量专家组(VQEG)和最新的电视标准[8]的合作努力中可见一斑。语音和音频质量(A-Q)评估技术有着更悠久的历史。语音和音频质量指标分别被标准化为PESQ[11]和PEA Q[7]。然而，视听质量(A VQ)是完全不同的事情。在过去已经有一些研究[2，13]，但在低比特率下做的工作很少。因此，我们设计了一些主题实验，使用移动应用程序中典型的内容、编解码器和比特率。根据这些测试的结果，本文对A-V编码参数进行了分析。关于实验的更多细节，音频和视频质量之间的相互作用，以及对数据的质量度量预测的评估，可以在[17]中找到。第二节从实验材料、测试条件和主体评价三个方面描述了实验设置。第三节讨论了视频编解码器和帧速率对视频质量的影响。第四节讨论了音频声道(单声道或双声道立体声)的数目和采样率对音频质量的影响。最后，在第5.2节中研究了音频和视频之间的最佳比特预算分配。实验AL SETUP2.1。A V Sour ce Clip源剪辑的内容和编码复杂度的范围被选为在移动设备上观看视频的典型场景的代表。源材料包括6个短片，每个短片长约8秒。这些场景的视频和音频内容总结为表1。视频素材为最初的TV格式；在我们的测试中，我们去隔行扫描并将其采样为QCIF帧大小(176x144)。音频源为16位PCM立体声，采样频率为48 kHz.2.2。测试材料
ABSTRA CTW e carried out a number of subjecti ve experiments for au-dio visual, audio-only , and video-only quality assessment.W e selected content and encoding parameters at very lowbitrates that are typical of mobile applications. Using thesedata, we explore the insuence of video codecs and framerate as well as audio channels and sampling rate on qual-ity. Finally , the optimal trade-of f between bits allocated toaudio and video inside a bitstream is investigated.1. INTR ODUCTIONV ideo quality (VQ) assessment [15, 16] has become ratherwell established by no w ,as evidenced by the number of re-search publications and products available, as well as thecollaborati ve efforts of the V ideo Quality Experts Group(VQEG) and recent standards for TV [8]. Speech and au-dio quality (A Q) assessment techniques ha ve an even longerhistory . Speech and audio quality metrics ha ve been stan-dardized as PESQ [11] and PEA Q [7], respecti vely .Audio visual quality (A VQ), ho we ver,is an entirely dif-ferent matter . There ha ve been a few studies in the past[2, 13], but little w ork has been done at low bitrates. There-fore, we designed a number of subjecti ve experiments usingcontent, codecs, and bitrates typical of emer ging mobile ap-plications. Based on the results of these tests, an analysisof A V coding parameters is presented in this paper . Moredetails on the experiments, the interactions between audioand video quality , and an evaluation of quality metric pre-dictions on the data can be found in [17].The paper is organized as follo ws. Section 2 describesthe experimental setup in terms of source material, test con-ditions, and subjecti ve assessment. The insuence of videocodecs and frame rate on video quality is discussed in Sec-tion 3. The effect of the number of audio channels (monoor tw o-channel stereo) and sampling rate on audio quality isdiscussed in Section 4. Finally ,the optimal bit budget allo-cation trade-of f between audio and video is investigated inSection 5.2. EXPERIMENT AL SETUP2.1. A V Sour ce ClipsThe content of the source clips and the range of coding com-ple xity w as chosen to be representati ve of a typical scenariofor w atching video on a mobile de vice. The source mate-rial comprises 6 short clips of about 8 seconds each. Thevideo and audio content of these scenes is summarized inT able 1. The video source material w as originally in TVformat; for our tests we de-interlaced and do wnsampled itto QCIF frame size (176x144). The audio source materialw as 16-bit PCM stereo sampled at 48 kHz.2.2. T est Material