Audio monitoring is the process of metering audio levels, using a visual display. This helps
maintain audio signals at their optimum level, along with helping minimise degradation. Broadcasters and recording companies employ audio monitors to help them assess the aesthetic merits of the programme, and to tailor the balance by audio mixing and mastering to achieve the desired end result. Loudspeakers are also an essential concept, required at various points in the process, to enable engineers to ensure that the programme is reasonably free from technical defects, such as degradation, audible distortion, or background noise.
The process of audio monitoring usually involves mixing the audio for it to sound appealing on the widest range of playback devices. These systems include high-end audio, low-quality radios, event arenas, car stereos or home stereos. Most professional audio-production studios employ several sets of monitors.
Prinyar Boon, product manager, PHABRIX, said, “The technical and subjective monitoring of audio is typically more involved than video. Audio workflows involve the production of many different packaged deliverables with many tens or hundreds of mic sources, dozens of stems, multiple mixes — say, for host and world feeds, multiple languages. An international sports host broadcaster servicing several unilaterals in addition to the world feed may have to deliver tens of video feeds, but several thousand channels of accompanying audio.”
There are a wide range of audio formats, from mono, dual mono, 2.0 stereo, to all the different combinations of multichannel and immersive channel and object-based formats. “Video by comparison, 3D aside, is essentially a mono format and it is much simpler to create a high-quality video monitoring environment than the audio equivalent,” added Boon.
THE TECHNICAL AND SUBJECTIVE MONITORING OF AUDIO IS TYPICALLY MORE INVOLVED THAN VIDEO. AUDIO WORKFLOWS INVOLVE THE PRODUCTION OF MANY DIFFERENT PACKAGED DELIVERABLES FOR HOST AND WORLD FEEDS, MULTIPLE LANGUAGES. – PRINYAR BOON, PRODUCT MANAGER, PHABRIX
“Audio is a critical, but often an overshadowed component of digital media distribution today. Audio channels have also been used to carry metadata such as watermarks so insuring the audio channels arrive as pristine as possible is very important,” explained Ted Korte, CTO, Qligent.
Subjective monitoring involves considering the technical aspects of the room design including shape and reverberation characteristics, layout/positioning of speakers and their calibration. This, then may lead to a nearfield mix for TV work, which is very different to the mix for movie production, or a mix for headphones. According to Boon, converting between formats and simultaneously mix-monitoring of said object, multichannel, and a stereo deliverable, requires a deliberated set-up and an understanding of the limits of the down- mix or rendering tools and their interaction with mixing techniques. Stereo up-mix to multichannel and back to stereo ‘round tripping’ may also need careful attention.
“A mix designed for theatrical distribution (far-field) will not cleanly playback through a professional near-field playback system, domestic TV speakers, or sound-bar, and needs to be re-mastered. Conversely, it is important to understand which application an asset has been mixed for, and ensure that it is delivered to the correct end point. From a timing perspective, it is important to maintain not only the relative phasing between channels, but also for audio-to-video (lip sync). This can be technically challenging to achieve and maintain for long periods of time,” explained Boon.
AUDIO IS A CRITICAL, BUT OFTEN AN OVERSHADOWED COMPONENT OF DIGITAL MEDIA DISTRIBUTION TODAY. AUDIO CHANNELS HAVE ALSO BEEN USED TO CARRY METADATA SUCH AS WATERMARKS SO INSURING THE AUDIO CHANNELS ARRIVE AS PRISTINE AS POSSIBLE IS VERY IMPORTANT. – TED KORTE, CTO, QLIGENT
Audio, particularly modern digital systems support high dynamic range (HDR). This has to be mapped onto the various listening devices while accommodating the specific characteristics, low dynamic range playback capability, or noisy environments. This translation is not easy to automate, and can lead to poor subjective quality or loudness issues, if not handled and monitored correctly.
Over the past few years, there has been a renewed focus on audio technology.The growing focus on the concepts of compression, object audio, immersive audio, surround-sound configurations, growth of podcasting, audio-only advertisements, and S2110 separates audio components for more enhanced operations. Audience feedback and behaviour can also be monitored and analysed, in real time.
“Many of the technical tools, along with a good pair of ears, are still valid today as they were ten years ago, and are at the core of any workflow. There are now tools that can better identify basic technical audio problems, which can take off the burden of monitoring hundreds of audio channels. Audio loudness meters have now been standardised and are readily available. Immersive and object-based audio is now being routinely produced and delivered for live sports production as well as blu-ray and OTT services,” explained Boon.
Personalisation is the need of the hour. Users, today, need easy access to selecting different sound viewpoints, languages, commentators, and narrators, without affecting the underlying mix. The ability to easily adjust the relative balance between dialogue and the audio bed, is also coveted. “You can choose to immerse yourself in the crowd, or take the crowd down to make the dialogue more intelligible!” exclaimed Boon.
According to Boon, adding a new live format to an existing service requires an understanding of operator working practices, training, and skill sets, so that the new technology can be blended-in without causing major disruptions. “There needs to be a clear understanding throughout the organisation, of the added value that the new format will bring. Simplifying the live-mix control and monitoring of multiple formats is key to enabling the smooth transition,” he explained.
File-based workflows are better placed to lend themselves to automation. Modern processors provide sophisticated, powerful processing and analysis tools with high throughput. Analysis of the different asset types and workflows, combined with a commercial model of peak versus baseline loading of infrastructure and how to best deploy near-line and online resources, is primary to the application of the audio monitoring technology.
Integration can be a tricky domain due to compatibility reasons. Moving to an IP studio environment or ATSC 3.0 environment opens up a host of alternatives. In any case, the alignment, latency, and quality of the audio must be verified early and often due to the wide variety of consumer devices, monitoring in the last mile, and end user environments.
COSTS AND EXECUTION
Our M&E industry is at a stage where the comprehension and accommodation of what people want or need, weighs more than the underlying technology itself. Vendors are working to keep the costs as low as possible, and the integration as easy as possible, but the ROI will still be difficult to measure. The advent and usage of revolutionising technology is considerably improving the overall experience with audio. Broadcasters will need to take some risks and try a few things. Anything new attempted, can change the game and pose as a major differentiator from competitors. The audio in ATSC 3.0 has been touted as one of the most desired features by end users.
Modern audio technology delivers a good value for money. A mixing board or workstation, which would have costed hundreds of thousands of dollars a decade ago, is now available at a fraction of that enormous cost. These new entry price points have widened the possibilities, instigating a thriving market for plugins and other accessories.