![]() It will also display the curve centered around this peak. Just click on a peak and VQA will display the distorted and reference frames corresponding to this peak. Level 3: You detect some peaks and you want to see the corresponding frames, to evaluate the quality of these frames by yourself.You just have to click on a link and VQA will display this curve. Level 2: So you'll want to have a look at the quality curve, to see if you always have a constant quality (all along the video) or if you have peaks of quality loss at certain moments.But most of the time, you'll think that this score is not good or not good enough (and that you can certainly improve it). If you consider that this score is good (or good enough), then you're lucky and your work is finished. ![]() Level 1: First you'll have a look at the mean quality score.Indeed, let's suppose that you measured the perceived video quality of a video file. Indeed, generally we consider that there are 5 levels of analysis. These different features help the user during results analysis. This will enable you to determine the bitrate which is required to get a given quality level. You can also get graphical representations of the perceived quality versus the bitrate. If several distorted videos have the same reference video, then you can draw all their curves on the same figure, in order to compare the effects of different encoders or different bitrates on a given video content. And if the boxes are annoying, you can make them invisible using a single click. The color of the box indicates the level of distortion (the clearer the color, the higher the distortions). If the frame corresponding to the center of the curve is a characteristic frame, then this frame and its reference frame will be displayed below the curve.Īnd if the distorted frame contains areas that have been distorted beyond an acceptability threshold defined by the user, then these areas will be boxed, so that you can find locate easily. And if you drag your mouse to select a portion of the curve, it will zoom on this selection. In the web interface, all curves are interactive: if you click on one point of the curve, it will put this point at the center and zoom by a factor of 2. To achieve that, VQA's video quality metrics having been trained using the results of subjective quality assessment tests performed with human observers.ĭuring video quality measurement, many windows can be displayed: measured video frame, reference video frame, seamless view (left part of the reference frame and right part of the measured frame), errors map, video and audio quality curves, video quality indicators curves and bitrate curve. Then VQA measures video quality indicators like blockiness, blur, contrast and flatness, and combine them to produce video quality scores highly correlated with human judgment. In fact, to avoid having to click too often, you can also do both operations (synchronization, then quality measurement) in a single click, thanks to the "GO" button. When the synchronization step completes, the detected temporal and spatial offsets are copied in the appropriate fields of the user interface and you can start the perceived video quality measurement and analysis step. If possible, the recommended configuration is: 4-core CPU (or more), 3 GB of RAM. measuring the synchronization between audio and video (lipsync) from files.automatic encoding/transcoding of audio video files by choosing the quality of produced files (you choose the quality instead of choosing the bitrate !).monitoring of file-based video encoding processes (example: encoding for VOD).compare blockiness, blur, contrast and flatness between two videos.video equipment R&D (example: video encoders R&D).video equipment benchmarking and optimization (example: video encoders performance benchmarking).VQA also enables to measure the skew between audio and video (lip sync offset). Video Quality Analyzer (VQA) is a very powerful software solution to precisely measure and analyze the video quality perceived by end-users (also called QoE: Quality of Experience).
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