If you work in post production audio you will have certainly heard of OP48 before. This was, until January 1 2013, the Free TV industry standard for audio levels. OP48 was a restriction requiring that the programme reference level be adjusted to -20dBFS (SMPTE RP.155). It also said that we humble sound engineers should not use compression, limiting and EQ, I quote, “for the purpose of producing excessively noisy or strident material”. This is of course extremely hard to monitor and regulate so we had the scenario where everyone was competing for the loudest TV commercial on air, all complying to the level requirement whilst using varying degrees of brutal compression and hard limiting to try to stand out above the rest.
From January 1 2013, Australia is officially catching up with Europe, the US and many other parts of the globe with the introduction of OP59, a new audio “loudness” standard. The difference between the old OP48 and the new OP59 is primarily where OP48 measured levels (VU and digital peak levels), OP59 measures average perceived loudness. This is how loud the audio material actually sounds to the human ear.
The International Telecommunication Union (ITU) developed a very interesting algorithm (currently ITU-R BS.1770-3) which helps audio engineers measure their soundtrack’s actual, measurable, perceived loudness.This measurement can be found by playing your entire mix through a meter calibrated to take your LKFS value, which for OP59 is -24LKFS.
The L is for Loudness;
The K is a measure of the fancy filtering algorithm used; and
The FS is simply for full scale (like in dBFS).
Whether you’re mixing a short commercial or a long-form programme, you now have to adhere to this new requirement. To arrive at your LKFS measurement, the entire programme or TVC must be played through the adhering meters. Luckily for us there are meters which can scan your mix for you much faster than in real-time, allowing us to get our LKFS measurement and adhere to OP59 relatively easily.
The final aspect of OP59 is of course the true peak limit of -2dBFS. Another thing to remember is that, like always, we’re still working with a fairly small window of headroom and if you leave any levels too low, they’ll fall below the ITU-R BS.1773’s gate.
I haven’t tried this yet but I hear you can actually mix some parts super loud (compressed) and other parts more dynamic and the measurement on your meters will comply as it is a measurement of the “entire soundtrack” average from A to B. Maybe this means we’ll still have the same audio loudness problems just with more sonic space within the commercials? Something to think about for you creatives next time you make an ad!
So we now have a uniform level requirement so (theoretically) all of our TVCs, programmes and IDs will sound the same on air, allowing people at home to relax during ad breaks without that trucker / voice over guy shouting at you about his homebush clearance sales at a higher than fair perceived loudness. Hooray!
So now you’ll be wondering who makes meters which comply to ITU-R BS.1770, right? Well the good news is most of the big guys have or are in the process of making metering software to measure this (remember, it has been in existence in Europe and the States for some time already). DK Technologies offer a range of Audio Metering Products which comply, TC Electronic have the LM6 and LM5D, Waves have the WLM (Waves Loudness Meter) and there are even freeware plug-ins such as the German made HOFA-4U.
So there you go, welcome to the new world of OP59!