Historically we had peak-level based (PPM) audio measurement and the compliance spec said we were not to pass a certain PPM level. Commercials exploited this by keeping the sound close to the maximum peak, and as a result, it was louder.
The new loudness specification
Over the last few years, the audio specification has been changed. The new Programme Loudness based specification is centred around the average audio level in a piece of media. With this form of operational practice, we are now able to take advantage of a wide range of audio dynamics which leads to much more creative and audibly pleasant audio. So the 1812 Overture will sound just as it would in a concert hall.
The Programme Loudness is expected to be the same value for a movie, a new bulletin, episodic content, as well as ads. You get some loud bits and you get some quiet bits, but you don’t feel instinctively, “this is way louder than what I was just listening to.” So when the programme changes to the commercial or promo, there isn’t the noticeable change in audio level that annoyed all of us.
Understanding loudness and the use of average audio levels is just one aspect of audio compliance processing. We have a new 10 Point Loudness Checklist to share with you. It’s designed to help decipher the complications and address the common misconceptions about compliance processing.
Top two misconceptions
The two most common misconceptions about Programme Loudness based audio compliance seem to be the following:
- “If I correct the average it might lower the dialog to the point of making it inaudible.” Fortunately, this is not true.
- “If there is a very loud section of audio, for example, a gunshot or a door slam, then the Programme Loudness compliance will suppress it and along with it the low-level audio.” Thankfully, this is not true, either.
Both the above statements are as a result of misunderstanding the correcting process. In order to change the average value (Programme Loudness) of the media, one simply needs to change the overall gain of the media. So, in Europe the Programme Loudness should be at -23 and if the Programme Loudness is found to be -20 a 3dB gain attenuation will bring the level to -23, or to compliance if you like. All we have done is change the overall gain to achieve this. We have not changed the creative mix.
Hardware or software: any difference?
In a file-based domain, it is possible to measure the file first and then change the global gain or overall gain, to achieve compliance. In the real-time world, as we don’t know what the average is at any point in time other than at the end of the programme, the hardware processor will constantly seek to take the average audio level to -23. What this is actually doing is constantly changing the gain and there for the creative mix.
Going back to the misconceptions, changing the overall gain does not change the ratio between the loudest bit and the quietest bit, and therefore, if the dialog can’t be heard because of the compliance, all the user has to do is increase the volume.
Operational implementation of Programme Loudness compliance has challenges, and there are misconceptions. We have produced a handy info-graphic that helps decipher the complications and misconceptions about audio compliance processing.
Click here to download your free copy of Loudness Compliance: The 10 Point Checklist. And, as always, feel free to contact us with your compliance questions.