QC Workflows Must Follow As Format and Distribution Methods Evolve

In this new technology-driven era where consumers can access and enjoy media on a vast array of platforms, file-based quality control (QC) is critical to maintaining the best possible image and audio output. From a viewer standpoint, bad quality represents another reason to watch something else. From a business standpoint, bad quality can mean content gets rejected for not meeting published standards. To complicate matters further, distribution formats continue to evolve along with the quality standards to support them. QC workflows certainly have come a long way since the days when “golden eye” expert reviewers would sit all day watching content on a color calibrated grade one broadcast studio monitor obsessing over quality.

Aiming to ensure that a rich and crisp piece of media is generated is one thing, but it must also comply with both technical and legal requirements as specified by the broadcaster or service provider. Is the file formatted correctly? Will it play out flawlessly? Are the captions, audio levels, and SCTE 35 ad markers all present, correct and within limits? There are also legal requirements that apply regionally throughout the world.

In a previous blog post we provided a quick guide into file-based QC workflows. Here we get into a bit more detail, and provide some information about Telestream QC workflows solutions.

QC workflows on output, QC workflows on input

Postproduction companies must check their content prior to sending to broadcasters, providers, VOD platforms, etc. Each client will almost certainly have unique technical and legal requirements. Failing to meet and/or comply with the requirements can result in rejection and fines in addition to the added cost of internally reprocessing the media. Repeated failures or rejections may jeopardize future contracts.

Service providers and broadcasters will also check incoming content from all sources to ensure they are starting with high quality files. They are checking for the same technical and legal compliance to ensure files will play on their systems. For incoming content, they may also check for the presence of advertising markers, as they are key to successfully monetizing their OTT streams.

While some aspects of quality control are subjective, it’s useful to employ an objective auto QC workflows solution that supports a non-reference MOS (Mean Objective Score) rating – a way of measuring quality in line with ITU scoring systems. This provides an overall perceptual quality check and allows identification of problems based on the human vision system. Telestream Aurora and Vidchecker are complimentary file-based quality control products. Both offer a comprehensive, up to date range of quality tests for video, audio and file containers. Each product is equipped with a set of default test templates for major broadcasters and OTT platforms, helping users quickly identify content that does not meet requirements.

Vidchecker additionally offers patented intelligent correction, which can fix files automatically, saving valuable edit suite time. Aurora offers the ability to process ABR packages and includes a number of features positioned for the growing OTT/VOD industry.

More than one QC workflows tool for the job

In many cases an expert operator must still manually perform a final check for image and audio quality, particularly on high value content. For that task they will require a frame accurate media player such as Telestream’s Switch Pro that can easily integrate with a color calibrated broadcast monitor. QC software should be able to integrate with a player, so faults are automatically identified on the timeline of the player. A high-quality commercial player like Switch Pro will play any media format and analyze metadata, time codes, audio levels and captions. Since humans are not well suited for checking compliance of technical specs or coping with high volumes of content, most companies will have a need for more than one QC tool.

A robust and predictable QC workflow requires an automatic file-based QC application such as Aurora or Vidchecker or a service like Telestream Cloud Qualify which can check large files much faster than manual operators and works 24 hours per day. These auto-QC solutions are very good at checking the detailed syntax of a file together with many objective checks such as video and audio levels, dead pixels, dropouts, and media offline issues. All these checks must be able to run on the widest number of formats such as ProRes, J2K, DNxHD, DPX, OpenEXR and IMF.

As complexity increases with modern delivery formats such as IMF, it can present a significant challenge for file-based QC. It is now necessary to confirm that a ‘package’ contains all the content that is specified in the manifest, while ensuring that all the “essence” components (video, audio, metadata) are compliant and of acceptable quality. Auto QC is really the only way to efficiently check complex IMF packages.

Location, Location, Location

When it comes to manual QC, there are two approaches—Local and Remote. In a local situation a player like Switch has direct access to the source file. It can play on a computer monitor or through an output card to a grade one monitor for expert viewing assessment. While there are free opensource players, these often have limitations such as dropping frames and may utilize non-approved codec implementations. They tend to focus on playing the media at all costs, and that may not mean playing it correctly.

A remote player, even for very large, professional-grade files, becomes necessary when a file is not available locally. If media is stored remotely and you need to review it immediately, a remote player like Telestream GLIM is invaluable. GLIM will save the time (which can be hours) and cost of downloading large files or transcoding the content into proxy versions for review. This type of media player must be extensible, through plugins or APIs so it can be easily integrated into existing workflows. For the maximum performance when playing large master files remotely, a purpose-built appliance with GLIM installed enables an expanded number of simultaneous sessions when compared to using an off the shelf server.

When it comes to QC workflows, organizations should have a choice of running the QC process in a public cloud, private cloud, or on their own servers. Ideally, any QC service should run wherever the media is located for best performance and lowest operational cost. Downloading a multi-gigabyte file master for QC could take hours not to mention the egress charges if it comes down from a public cloud.

When considering running a QC service in the cloud, it’s important to consider how the service was created. Many first-generation QC applications were developed to run on the Windows OS and were designed for on-premises servers. While these can be “fork-lifted” to cloud computing, it is far from an ideal solution. A modern cloud-native QC service should be based on a container architecture, running on the Linux OS, that supports a scalable workflow. This enables faster spin up times and reduces costs by offering a more appealing ‘pay-as-you-go’ business model. A cloud-native QC service, like Telestream Cloud Qualify, is also the best solution for coping with sudden bursts of demand, and for smaller operations with unpredictable capacity requirements.

Humans and Machines Working Together

Any conservative auto QC system can be expected to produce a number of false positives. In these cases, it is best to defer to an expert ‘human’ viewer who can decide whether these are genuine faults that require correction, or perhaps an intended editorial decision. For example, a long period of black and silence could be a legitimate fault or a creative storytelling decision. A well-designed QC system should be able to provide a list of time codes for the operator to review, allowing them to view only the sections in question, rather than the whole file. Only by letting humans and machines each do what they are best at doing can we achieve maximum quality and efficiency.

QC Workflows Conclusion

There are many different types of QC applications and services available. Depending on where an organization sits in the media creation and distribution pipeline, QC checks may be required on source media as well as on processed media. As more businesses place master file deliverables in the cloud, remote QC services that operate where the media resides have become crucial to maintaining efficiency and low cost.

While some aspects of quality control are objective, it’s useful to employ an auto QC solution like Aurora, that supports a non-reference MOS (Mean Objective Score) rating. This provides an overall perceptual quality check and allows identification of problems within content based on our understanding of the human visual system. As with Telestream Cloud Qualify, any capable QC workflows solution should support cloud-native operation as well as cloud-agnostic operation, so it is able to run in any public or private cloud computing infrastructure. For many customers having different control methods such as APIs and SDKs for developers, plus a flexible GUI for quick manual operations is also advantageous.

A comprehensive file-based QC solution should offer different business models to suit the unique requirements of an organization. This includes standalone applications, cloud-native SaaS, and APIs for developers creating their own purpose-built solutions. Telestream has a range of QC solutions that operate at every point of the media creation and distribution workflow whether on the ground, in the cloud, or both.

For information about the QC products mentioned in this post, you can click the links below:

Switch Pro: professional media player for Mac and Windows.

GLIM: professional media player that enables remote media review of large professional-grade files in a browser. With GLIM there is no need to work with proxies or download large media files just to view them.

Telestream Cloud Qualify: cloud-native, file-based QC service.

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