2018年3月23日
By 1月时特约编辑
专题文章

莫斯科国家更新VQMT与新的指标

Moscow State University’s 视频质量 Measurement Tool (VQMT) has always been one of the least expensive and most functional quality measurement tools available. 最新更新(10).0和10.1)添加新指标并提供重要的用户界面, 表演, and feature enhancements that make it a must-have upgrade for all serious streaming video producers. 像以前的版本一样，产品花费999美元 with upgrade pricing available for some owners of previous versions. Here's a brief overview of the new features, which we explore in a video at the end of this article.

顺便说一下背景, VQMT is a Windows application that also runs via the command line in both Windows and Linux environments. VQMT是一个非常灵活的工具，包含超过15个指标, 包括引用和非引用, 很多都有不同的变化. The UI version can compare one or two compressed files to a single source, which is great for comparing different encoding techniques or encoding configurations.

在UI中，VQMT将结果绘制成图形(参见图1) so you can gauge 表演 over file duration and identify problem areas. 例如, 图1 compares the same file, an excerpt from 钢铁之泪, encoded using constant bitrate encoding (green) and 200% constrained VBR encoding (orange) measured using the new VMAF metric. 虽然平均分很接近, the big green drop off around 30% into the file indicates a potential problem area as does the sharp downward spike on the extreme right.

图1. 对比CBR和200%约束VBR的结果图. 注意左上角的多个选项卡，下面将进行讨论.

您可以将滑块移动到图形中的任何一点, and then click Show Frame on the bottom right to view the source and two encoded frames. It’s a great way to identify any problem areas and to see if the scores actually reflect artifacts that would be noticeable by your viewers.

主要新特性

In terms of new metrics, Netflix’s VMAF is very high on the list. 自从VMAF在20世纪10年代出现以来，我就一直在与它合作.0 beta, and at first the analysis was single-threaded and exceptionally slow. 从那时起, MSU has done a great job accelerating 表演 on multiple-core computers like my HP Z840; while VMAF is still slow because it involves multiple metrics, 现在很好用了. 10新功能.1 is the NIQE metric, reportedly one of the best non-reference metrics available.

从UI的角度来看，版本10.0 represents a complete rewrite, which initially is jarring but ultimately is vastly superior. 有多种可用性增强, including the ability to drag and drop files into the main screen, 很方便. 更多的 important is the ability to run multiple tests simultaneously, as evidenced by the multiple tabs on the upper left of the figure.

这是, 首先你开始度量计算, 您可以加载新的压缩文件和源文件到程序中, 然后开始另一个分析. In previous versions, the program was locked until the initial computation completed. Though you could load multiple instances of the program (and you still can), 这很麻烦，而且容易崩溃. 我已经在版本10中运行了10个同步分析.1 without so much as a hiccup, a great way to leverage the 40 cores on my Z840.

The other great usability enhancement in the command line is the ability to analyze files of disparate resolutions without first converting them to Y4M format. 例如, to compare a 720p file against the 1080p source in previous versions, 您必须将720p文件缩放到1080p的Y4M文件. 它既简单又快速, 但这是额外的一步, and if you’re analyzing 100 files overnight or over a weekend, 和/或处理4K或更大的文件, 您可能没有可用的磁盘空间来执行此操作. In version 10, you can now compute any metric without first converting to Y4M.

举个例子, I recently completed a 2700p60p VR project that involved 3-minute test files, 每份150GB，格式为Y4M. 如果我必须预先转换成测试, 我可以测试大约5个文件而不会耗尽磁盘空间, 严重的限制. 有了这个新功能，磁盘空间就不再是问题了.

虽然这些特征听起来可能很普通, they vastly increase the testing throughput possible with VQMT. If objective quality metrics are an important part of your configuration and testing practice (and they should be), 因此，最新的升级是绝对必要的.