In this story, 我将介绍质量控制程序的功能以及如何以及在何处将它们集成到您的生产工作流程中. Then, 我将列出一些在选择质量控制项目时需要考虑的事项, 我将分享四个来自Interra Systems的质量控制程序/功能的高级迷你评论, Inc.; Rhozet (part of Harmonic, Inc.); Tektronix, Inc.; and Telestream, Inc. 最后，我将列出为其编码系统提供QC系统或QC功能的其他供应商.
How Do I QC?
QC系统有两种基本类型:独立系统, such as Interra Baton and Tektronix Cerify, and QC functionality integrated into more general encoding systems, such as Rhozet Workflow Systems and Telestream Vantage. At a high level, all QC systems work similarly; you define the tests to be performed, the notification and pass/fail options, and the files to be examined, 可以位于本地或网络文件夹或通过FTP检索. Beyond these similarities, however, 集成编码器/质量控制系统倾向于将质量控制功能编织到摄取/编码/交付工作流程的各个阶段, 而独立系统具有定义良好的功能口袋，易于从独立编码器或媒体资产管理(MAM)系统访问.
For example, Figure 1 显示来自独立QC程序Tektronix certificate的配置文件创建屏幕. In the lexicon of the Cerify system, 当您将配置文件应用于一组媒体文件时，将启动QC作业. 配置文件最多包含四个预定义，用于定义要执行的测试和测试后操作. Like most QC systems, certificate将测试分为单独的预设，这些预设检查容器格式以及音频和视频质量.
Post操作可以包括电子邮件和文件传输功能, so files that pass can be sent to a distribution bucket, while files that fail can be sent to a reject bucket. 典型的工作流程可能是您的独立编码工具将一组文件交付到触发certificate分析的监视文件夹. When complete, 然后，certificate将文件传输到由MAM监视的文件夹以进行分发, 将不合格品发送到另一个文件夹进行人工检查.
The integrated approach is shown in Figure 2, 其中包含来自Rhozet工作流系统(WFS)的工作流。. 在wfs中，工作流定义了文件摄取之后发生的所有步骤. You see QC functionality in two areas: pre-transform, where I’m testing for letterboxing, black frames, and confirmation that the file is 720p, and post-transform, 我要搜索掉帧和过多块，并确保文件在两个比较QC测试中满足某些最小值, 结构化相似指数法(SSIM)和峰值信噪比(PSNR).
通过单击“启用操作员对阴性结果的审查”复选框, WFS将把任何标记的文件移到WFS界面的Pending QC选项卡中. From there, the operator can access the file, view the specific problem areas, and decide whether to pass or fail the file.
Where Do I QC?
Rhozet工作流强调可以在工作流的多个步骤中部署QC, including pre-encode and post-encode. Before encoding, 您可以检查以确保文件符合您的期望，这样您就不会浪费编码 resources on a file that will end up in the reject bin. For example, 图3显示了可以从Interra Baton运行的一些测试, including pixel aspect ratio, video format, resolution, frame rate, display aspect ratio, and scan type and scan order. Most tools, 包括接力棒(另一组测试)也可以检测到信箱或窗帘/柱子, black frames, audio levels and silence, 以及在编码之前应该将文件踢出的许多其他问题.
Some systems, such as Telestream Vantage, 能否查询传入的文件并根据其特征做出工作流决策. It’s probably too small to see, but in the workflow shown in Figure 4, Vantage先确定文件是高清还是标清，然后再确定文件是盒装的还是卷帘的. 基于这些决定，使用不同的预设对文件进行编码.
编码后，您应该检查编码文件的质量和一致性. A good example of conformance types of test include those shown in Figure 3, which are the format-independent tests available in Baton. Beyond these are quality-related tests such as PSNR, SSIM, block用于视频和剪辑，level用于音频. Finally, 您应该检查特定于格式的一致性，例如profile, level, and entropy coding for H.264 video, particularly if you’re pulling together materials from disparate sources.