Loudness is a tricky business

Tuesday, June 12, 2012

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eFF isn’t the answer to everything. You can’t stick a microphone out of a window and expect eFF to make the recording sound like it originated from Abbey Road. For us to apply appropriate loudness compliance corrections, a good job has to have been done on the material in the first place, and therein lies part of the challenge.
Our business is built on the premise that as the number of operations that migrate to file-based workflows increase there will be a substantial need for software-based signal processing tools that work in the file-based domain. MC Patel from Emotion Systems believes there are many automatable operations related to measurement, analysis and correction that can be implemented by dependable, accurate, low cost and easy-to-use software applications.

The key is to identify and fix no-compliant file-based content without touching what needs to be left alone. Our first product is “eFF audio” (eFF: Emotion File Finish), a loudness compliance application, but our journey in the development and implementation of eFF has revealed additional issues in terms of measurement, analysis and compliance that are worthy of exposure and discussion. 

Provenance
Emotion Systems is a software development company focussed towards file based workflows, and very market driven, an operational aspect of which we’re proud. Based on feedback we’ve received from our customers, the software platform we’ve built is, in essence, a technology framework that has by design, potential for additional applications for analysing and resolving issues with not only audio, but video, timecode and metadata.

We have been building the platform upon which eFF is based for more than two years. It is therefore refined to a point where we are able to fix only the elements of a file that a customer wants fixed. When we open a file and look at the video, audio and metadata, not only can we fix certain items, we can also use that opportunity to do non-invasive analysis that enables the customer to make informed decisions about the best way to manage and process those files in their particular facility.

That said, eFF isn’t the answer to everything. You can’t stick a microphone out of a window and expect eFF to make the recording sound like it originated from Abbey Road. For us to apply appropriate loudness compliance corrections, a good job has to have been done on the material in the first place, and therein lies part of the challenge.

Even if an audio file has been carefully mixed and prepared, the material still has to meet a substantial range of specifications for different broadcasters, and meeting those various specifications is an incredibly difficult thing to do, primarily because content providers haven’t entirely worked out how best to mix to meet multiple loudness standards. This is no disrespect to them, it’s just that those standards are new and evolving, which makes them difficult targets to hit.

Legacy Material
An even bigger problem is legacy material. Historically there were no standards in use relating to loudness, so materials mixed to an audio standard related to peak measurement. Legacy material may need to be remixed to comply with loudness.
With the advent of loudness compliance standards you have to adapt, for example, a cinema mix that has a very broad dynamic range designed for large theatres, to a mix that’s suitable for broadcast. A loudness compliance tool can make sure that whatever comes out complies, but a lot more needs to be done to adapt a cinema mix to a smaller environment. Such processes are generally conducted in an audio suite, but that’s a costly, time-consuming process that’s crying out for a lower cost automated option to obtain the same result.

People are therefore beginning to ask us to provide a tool like eFF that could assist in creating this or a range of other types of mix suited to an automated workflow.  The answer is that such a product could indeed be developed and we’re in active discussion with our customers to explore its viability. 

Operational Challenges
One particular challenge in the UK is in the commercials market, where stereo audio is typically supplied to a specified PPM level. This present level has been working fine over the years for tape-based delivery. However, UK Post is increasing having to produce and deliver content globally and so needs to supply loudness compliant deliverables as determined by their customers legally bound requirements. As we’ll subsequently cover in this article, eFF facilitates this easily through use of customisable profiles that can be defined for specific compliant deliverables.

As file-based delivery becomes ubiquitous, the use of MXF based broadcast workflows has increased significantly. While MXF is flexible, it is also loose in its standards rigidity. The Digital Production Partnership in the UK has been working on a tighter specification that uses an MXF container called AS11, and file-based delivery will have to comply to that specification. eFF supports AS11 as well as .wavs, AIFF’s, .mov’s and MXF.

In the US and many other countries people have to deal with 5.1 audio and stereo files, all of which arrive as individual mono files. The sum of the 5.1 files need to be examined to determine where the loudness problems are, and then fix them individually. Again, not easy, but through focussed interaction with our clients we have engineered an elegant solution..

Within the file-based delivery there is still the presence of tone and silence before the start of essence. And therefore eFF allows these to be ignored during the measurement and correction process. We only measure and correct the essence.

Evolving Compliance
As the world migrates towards loudness compliance you would think that the standard would be definitive in the sense that it would describe all measurements and all forms of correction. However, individual broadcasters worldwide make working practice choices based on allowable variations within loudness recommendations, and many of them differ substantially.

What’s more, those standards and the variations thereof are still evolving, so it’s still a moving target. Even more important, existing workflows, standards and practices are usually deeply entrenched in an operation, so any changes required to comply with tomorrow need to be incorporated within what you are doing today, and you need to  be able to do both while the transition is occurring. This has been, and will for some time remain, an issue. 

Files Mixed for Loudness Compliance
Files that have been mixed for loudness may still require minor adjustments; especially if they need to be delivered to multiple countries, and that’s something at which eFF excels.
eFF provides support for legacy workflows and facilitates the creation of customised profiles to enable comprehensive variations on the chosen standard. Every piece of content that needs to be repurposed can have a unique profile, so you can have a French profile, a German profile, a British profile and eFF can measure to each profile and correct for it so the user can create compliant content for each broadcaster.  We can do that because all legacy measurement meters have been included in eFF. So if a user needs to deliver to a PPM, VU or any other spec, eFF can do it and do it well. 

MXF
Another other area where our observations tell us there are some challenges (which we have now addressed) is the use of MXF as a container. Basically, MXF is a media exchange format that allows media to be moved with a great deal of ancillary information. However, though MXF is an extremely flexible format on the plus side, there are also intrinsically very few rigid standards on the downside, which in turn can often lead to issues of interoperability with the potential to becoming a significant problem.  

eFF is, however, largely agnostic to these issues. eFF has been tested and continues to be tested with a comprehensive range of MXF files derived from a wide range of sources. For MXF’s (as well as MPEG’s and MOV’s) we unwrap, measure and fix audio files, and then reinsert the fixed audio and re-wrap without any degradation of the original essence. Video and metadata essence is completely untouched. One of the key features of eFF is that results are 100% accurate, repeatable, and above all dependable. 

Although there are considerable variations in MXF, we have designed a robust framework that allows us to readily resolve any issues with the variations in an MXF file without breaking its structure.

Conclusion 

In our mission of making an easy to use, highly accurate and cost-effective product that’s automatable, we have proactively worked with our customers to identify their workflow and compliance issues and dynamically adapted that product to address the challenges we have just discussed.

Another key aspect for us has been the benefit gained in identifying which aspects of non-compliance may need to be resolved using a different process or desired end result. What we currently offer is a solution to one particular aspect of compliance – that of loudness. However, in developing our solution, other file based non-compliance related issues have clearly emerged that might require an entirely different approach to resolve. Our software architecture lends itself elegantly to be adapted to resolve these issues, and over the coming 18 months we will see the emergence of an entirely new and distinct range of products to tackle them. 

Whatever we do, what matters to our customers is that we can be trusted to find and provide cost effective solutions to a range of issues and problems within their file based workflows. Our core philosophy is to create working solutions that are simple in operation and de-skill previously complex and costly original methods that may or may not have achieved the same result. That is our commitment.

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