Audio monitoring: critical to visual media services


Simen Frostad TV-Bay Magazine
Read ezine online
by Simen Frostad
Issue 89 - May 2014

Its a fact of TV broadcasting that audiences will tolerate reduced visual quality much more readily than any impairment to the audio. So long as the audio continues and is intelligible, viewers tend to put up with glitches in the video or even temporary loss of picture. But if a broadcaster lets the audio quality drop or loses audio altogether, thats when the viewer gives up and switches channel.

So audio quality is critical to TV and video media services. And if audio monitoring seems to lurk in the shadows in the context of digital media services, while the monitoring of video occupies the spotlight, it is perhaps because audio is such a vital part of the service that it is unquestioned.

The nature of human perception also has something to do with this. An operator can sit at a monitoring console and comfortably eyeball 50 services or more concurrently, with a well-designed display. But its quite impossible for anyone to monitor more than one audio source at the same time. So the audio monitoring has to be done robotically in the background, and only when error conditions arise does a visual alert make its presence felt.

In a system like the Bridge Technologies VB288, the immediate impression is of video monitoring activity because the content extraction processes continually display each channels video stream. The audio monitoring is happening too, but without a visual presence on the display until a service degradation or failure occurs.

In fact theres an lot of audio monitoring going on under the hood. This is because audio monitoring has become extremely demanding, with loudness compliance required by law, and with widespread use of surround sound audio. Monitoring systems like the VB288 have to continuously decode the audio to check for loudness compliance, and for the presence of all the components of a surround sound source. For the service provider, its a serious failure even if just one of those 5.1 or 7.1 components disappears.

Add to this the load involved in multiple-language services, where there might be five language sources for a channel, each with 5.1 sound (making 30 channels to check), and the audio monitoring requirement for a visual media service becomes very demanding.

As always when a lot of services need monitoring, the design of the monitoring technology is critical to efficient operation. If the monitoring information is presented clearly in a way that allows a small number of operators to keep on top of a large number of services, this benefits the service provider not only in terms of cost but in higher service quality too: when operators instantly get the information they need, repair times are dramatically shortened.

One big difference between audio and video delivery may be about to disappear. Unlike the video component of a service, the audio component has hitherto been delivered at one quality level only. While H264 adaptive streaming to mobile devices downshifts the video quality when receiving conditions mean that the bandwidth is inadequate to view the better quality without buffering, the audio continues to be streamed without this adaptation.

H265/HEVC may change this over the next twelve months or so. The video part of the specification is pretty settled, but there are still different directions on the audio. So while H265 compliant monitoring systems will have to support all the codecs in the same box (MPEG-1, MPEG-2, AAC, HE-AAC and beyond), there may also be provision for multi-versioning adaptive audio in the specification.

Whatever the outcome of this process over the next years, theres the prospect of greater diversity in audio delivery, and therefore in audio monitoring. Digital media service providers will need to keep abreast of these developments, and build monitoring systems that handle the audio monitoring requirement elegantly and efficiently, as part of the overall monitoring environment.


Tags: iss089 | bridge technologies | audio monitoring | Simen Frostad
Contributing Author Simen Frostad

Read this article in the tv-bay digital magazine
Article Copyright tv-bay limited. All trademarks recognised.
Reproduction of the content strictly prohibited without written consent.

Related Interviews
  • Bridge Technologies QoE Monitoring with Mobile Videowall Display at IBC 2013

    Bridge Technologies QoE Monitoring with Mobile Videowall Display at IBC 2013

  • Bridge Technologies PocketProbe App at NAB 2013

    Bridge Technologies PocketProbe App at NAB 2013

  • Bridge Technologies at IBC 2012

    Bridge Technologies at IBC 2012

  • Bridge Technologies at IBC2011

    Bridge Technologies at IBC2011

  • The Telos Alliance at IBC 2016

    The Telos Alliance at IBC 2016

  • Wohler at IBC 2016

    Wohler at IBC 2016

  • TSL Products at NAB 2013

    TSL Products at NAB 2013

  • TSL Systems at BVE 2013

    TSL Systems at BVE 2013

  • TSL Products at BVE 2013

    TSL Products at BVE 2013

  • TSL at NAB 2012

    TSL at NAB 2012

  • Murraypro at IBC2011

    Murraypro at IBC2011

  • DK Technology at IBC2011

    DK Technology at IBC2011


Articles
AI in Media and Entertainment
David Candler Artificial Intelligence (AI) is a term appearing everywhere these days. What is happening in media and entertainment (M&E) that makes the industry ripe for AI? In other words, why does the M&E industry need AI?
Tags: iss134 | AI | wazee | David Candler
Contributing Author David Candler Click to read or download PDF
An Obituary to Timecode
Bruce Devlin - new A stoic and persistent character that stubbornly refused to change with the times, Timecode has finally passed on, but no-one has noticed. A long-lasting industry veteran, Timecode was brought into this world at an uncertain date in the late 1960s due to the needs of analogue tape workflows and the demand for synchronisation between audio and video devices. A joint activity between SMPTE and the EBU led to the work on Time and Control codes starting its journey to standardisation in the early 1970s.
Tags: iss134 | timecode | smpte | ebu | edit | Bruce Devlin - new
Contributing Author Bruce Devlin - new Click to read
Giving Welsh sport a global audience
Adam Amor From the Ospreys Rugby Union team, to the Football Association of Wales, as well as national cycling, swimming and boxing coverage, Port Talbot based Buffoon Film and Media has been heavily involved in putting Welsh sports on the world stage.
Tags: iss134 | blackmagic | atem | buffoon | micro studio camera | Adam Amor
Contributing Author Adam Amor Click to read or download PDF
Keeping it remotely real
Reuben Such Everyone wants to do more with less. Always have, although it could be argued that doing more with more is something to aspire to, not many have that luxury. So let’s stick with the prevailing winds of doing more with less, and not just doing more, but doing it remotely, particularly in terms of production. Remote production, in particular, is getting a lot of attention in the field these days, but not so much in terms of the remote operation of fixed studios.
Tags: iss134 | remote control | IPE | IDS | Reuben Such
Contributing Author Reuben Such Click to read or download PDF
Accelerated Workflows with eGPU
Mike Griggs From the UK’s National Trust to magazine publishers to manufacturers, digital content creator Mike Griggs has a wide and varied portfolio of clients for whom he creates 3D art, motion graphics and multimedia exhibits. A typical day might involve sampling birdsong near Virginia Woolf’s country estate or creating 3D animations for VR. To keep on top of these demands, Griggs wanted to take the full power of the GPU computing revolution on the road.
Tags: iss134 | sonnet | egpu | amd | post production | editing | Mike Griggs
Contributing Author Mike Griggs Click to read or download PDF