Whether you are a traditional broadcaster, a content aggregator or a network services provider, today you have access to more file-based digital content than ever before. And compared with just 10 years ago, there are many new sources for broadcast-quality video and audio content. Archives are growing every day, and the variety of standards and formats that you may need to support this is still evolving.
Adding to the complexity of the problem — and thanks to a wide variety of enabling digital video technologies and new advances in consumer electronics — there are more opportunities to reach viewers. Empowered by the Internet and enabled by a variety of new consumer electronic developments, content viewers have developed new expectations about what they watch, when they watch it and what they watch it on.
With the inherent operational advantages in an all-digital workflow, many are looking for a practical application of the technologies that will make their organizations more efficient, more differentiated among the competition and ultimately more profitable. Success can mean optimizing and ensuring the quality of your content to gain maximum return and getting content in front of more viewers.
Rapidly changing environment
The video ecosystem is comprised of the companies that produce and post content, companies that deliver content, and the manufacturers whose products and technologies have enabled delivery of content to the consumer. The video ecosystem has changed considerably over the last decade, with the addition of new digital video technologies that have enabled file-based content across the broadcast industry and in our everyday lives.
Where service differentiation is becoming more transparent, the watchwords are “content is king.” Factors that could help differentiate one provider from another will likely include the perception of quality of what the consumer sees. Ensuring and optimizing file-based content quality means evaluating and reacting to media quality inside your network and understanding the impact your content can have on other elements in the ecosystem as well. It's not just the audio, video and metadata that matter now; format and syntax are critical.
Content providers, content aggregators and broadcasters have been building file-based content archives for years, and many have taken advantage of the opportunities to evolve their workflow to support an all-digital environment. Because more content is being compressed and archived in one format and then repurposed to another format, archives are anything but homogenous, and working to maintain control over your facility's output can be challenging.
Analysis of file-based content
With the proliferation of available content, it is unreasonable to think an operator can personally look at every piece of content prior to delivery. With the vast array of formats and standards, it seems even less likely that a visual inspection would uncover the unseen concerns that revolve around digital compression technology. In this new digital world, what are the new quality parameters that must be considered, how can they impact your business and how can they be measured?
Ensuring the quality of file-based assets means more today than simple validation of color space compliance and ensuring legality of the content. Appropriate analysis of compressed file data can uncover format-related issues in addition to identifying errors that can be created when video and audio are encoded (compressed). Tools are available to help you do this without the need to decode and visually inspect. These are some of the problems that file-based content verification can uncover:
- Incorrect play time.
- Incorrect stream setup.
- Transport stream errors.
- Multiplexing errors.
- Missing metadata used by an automation system.
- Incorrect bit rate for the video or audio.
- Encoding quality errors, where the encoder produces a series of blocky video frames.
- MPEG encoding syntax errors, which can occur due to multiple mux/demux operations, or an encoder blip.
- Errors in the syntax of the video and audio elementary streams.
Any one of these items could catastrophically affect the quality of what the viewer sees and hears — or doesn't see and hear. File-based digital content lends itself well to an inside-out look. While proper analysis can help you optimize content quality, it can also significantly help you to understand how the content may impact other elements in the ecosystem. In addition, it could give you a leg up in the struggle to differentiate yourself with viewers.
The following section discusses some of the opportunities afforded by new file-based quality control tools available today.
Will a file decode correctly and be viewable by my customer? If your viewer uses a set-top box to decode and view content, the set-top box will expect data in a specific format. The most effective way to check the health of file-based content prior to transmission is by verifying that the syntax of the file is correct. It is useless checking gamut if the syntax is incorrect, so syntax must be the first check. There is no sense in ensuring a file looks good if it can't be decoded at delivery.
File-based video generally comprises one or more complex digital file(s) with many elements, all of which must be correctly decoded for the file to play. A large proportion of file-based video has syntax errors, so it's important to look for tools that can automatically check for correct syntax, enabling you to find the errors before you get complaints that the consumer's set-top box has crashed.
When designing or buying equipment that encodes, decodes and transcodes content, can you optimize the quality of the output to provide a better user experience?
When organizations want to assess how an audience will react to content as viewed on a specific medium (TV set or movie screen), they will employ a group of professional viewers to view content. The industry standard for subjective picture quality measurement is defined by ITU-R BT.500. This standard defines a variety of conditions to measure the picture quality of the image, such as display type, viewing distance, viewing environment and viewer characteristics.
This kind of evaluation requires that a designer validate during several steps of the design process, provide viewable content in the appropriate format and ship it to a third party that then arranges the human viewing exercise and produces a written report.
Picture-quality analysis tools can help provide an objective analysis of encoder and decoder performance and reduce the evaluation period significantly for new components. Such tools can shorten design time and optimize designs.
In addition to ensuring the quality of the content inside your facility, you have an opportunity to impact the user experience when selecting the encoders and decoders for your facility. The process used to select components should include a consideration for components that are specifically designed and fine-tuned to deliver the highest quality to the consumers' particular viewing medium. Selecting encoders and decoders that score well in an objective comparison could positively affect the viewers' perceptions of the final content. This may be a particularly important consideration if you are repurposing content for multiple destinations and customers.
With the proliferation of digital file-based content and the inherent cost advantages that can be achieved by repurposing content archived in one format for use in another, broadcasters are faced with many new technology challenges.
In the file-based state, there are considerations that can be evaluated without decompressing and decoding. Parameters that affect image quality, systems interoperability and general user experience can be evaluated while the content is file-based.
File-based content analysis tools come in a variety of shapes and sizes. Each brings a specific set of values as a solution in your workflow. Keep the basic levels of analysis in mind as you design the workflow, or discuss with your engineering and operations staffs how you might optimize it around file-based content.
You want to ensure that you have the highest quality content possible coming into the system because there will be loss of quality during any compression process. Ensuring the color space compliance of incoming content in an uncompressed state, or while it is still in the production workflow, is a great start.
The first opportunity you will have to evaluate the file-based content in your facility is likely to be at the point it is ingested into the workflow and deposited on a facility server. Ensuring proper file format and syntax at this point, in conjunction with adequate network management discipline, could be enough to ensure that good data enters the system and isn't adversely affected by the system. This can be especially true if the operation doesn't include transcoding or decoding/encoding prior to distribution.
In some instances, you will receive content from a production facility that has already been compressed for distribution and is in the format that you will ingest into your system. In these cases, encouraging your supplier to verify file-based content to your quality standards could improve efficiencies at both facilities. Evaluation of file-based content at ingest may be the appropriate level for your facility.
Monitoring file-based content
More complex workflows often will include multiple points in the process where content is transcoded from one format to another or ultimately repurposed prior to delivery. Each time the content of the file changes, there is risk of introducing errors.
File-based QC tools, which are network-enabled, can be positioned throughout a facility workflow and provide invaluable data relative to the health of the content as it progresses through the facility. In simple environments, this means concentrating on evaluating the compressed content at ingest and just prior to distribution out of the facility. In more complex environments, it may mean evaluating the health of compressed video and audio files after the initial encode and then following each re-encode or transcode that occurs.
The impact of your content
With the proliferation of digital file-based content and the inherent cost advantages in repurposing content archived in one format for use in another, broadcasters are faced with many new technology challenges. Key areas of concern include:
- InteroperabilityWill a file decode correctly and be viewable by my customers?
- User experienceCompared with the original, how will the repurposed content be perceived when viewed by my customers?
- Equipment/process optimizationWhen buying equipment that encodes, decodes and transcodes my content, how can I optimize the quality of the media viewed by my customer?
Content creators, broadcasters and equipment designers use file-based content verification to determine how the products and services they provide impact the video ecosystem by ensuring standards compliance, checking syntax, and optimizing encoder and decoder designs based on predictive image quality measurements. There are advantages to be gained leveraging the technology behind file-based digital content.
Jon Hammarstrom is senior video marketing manager for Tektronix.
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