Is your film’s sound mix actually ready for broadcast and streaming?

Recently we did a theatrical sound mix for a film that was picked up for a national TV broadcast and it’s streaming platform. TV has different audio standards than a movie theater, so the mix needs to be tweaked to meet those specifications. We delivered what was required, and the mix also passed QC (Quality Control) in preparation to go on air.

Problems Occurred

However when the broadcast did air, we immediately noticed that the sound was not what we expected when viewing the website stream. The volume was pumping up and down, the music drowned out the dialogue, the loudest moments were very quiet while the quietest moments were very loud. We followed the network's audio specifications exactly. So what happened?

Long story short, the film and it's audio were processed differently depending on the viewing platform. The “on air” broadcast sounded different from the mobile app, which sounded different from the website stream. Different people heard different things, and the end result got a very mixed reaction. 

It became a confusing puzzle to try and solve and presented a challenge for everyone from the mixing engineer, to the broadcaster, and the viewing audience. 

So how do you know your film will play back in the way you intended? And how do you prepare for the variables of multiple platforms and new technologies?

The answer isn't simple, but we'd like to provide some insight to the practices in place which aim to solve this problem. 

Loudness Specifications

When producing sound for video and film, you must consider where it will play. This mainly includes theatrical, streaming, broadcast, and web. Different platforms are calibrated to different audio specifications, and it's critical that your sound team masters the final deliverables accordingly. 

Audio specifications are typically measured in two metrics: Integrated Loudness and True Peak.

Integrated Loudness is an evaluation of the average loudness of the entire program from beginning to end. It's measured in the unit LKFS. Average loudness helps us to know that the volume of the program is consistent throughout. We don't want the volume of the movie as a whole to drift up and down. Think of this as long term volume. 

True Peak is an evaluation of the loudest moments of the audio. It is measured in the unit dBFS (Decibels Full Scale).  This dictates the maximum allowed momentary loudness. This helps us avoid explosive sounds blasting our ears, blowing out speakers, and distorting. Think of this as short term volume.  

The general U.S. audio specifications for regulated content for traditional broadcast and streaming platforms is -24LKFS Integrated Loudness and -2dBFS True Peak.

Internet content such as YouTube and Vimeo is not as regulated, but they do have their own specifications. The average loudness is generally recommended to be around -14LKFS, but it is up to the content creator to follow this rule.

These specifications will still vary depending on the platform. It's important to check those requirements before the mix is started so the sound is optimized for each specific delivery.

Controlling Playback

We are in a time where we can no longer apply universal standards to evolving platforms. The known specifications are not difficult to meet. It’s the new technologies that present these novel issues.

Many streaming platforms, including web, mobile apps, and hardware devices now include some form of loudness and dynamic range controls for audio. This is done in an attempt to ensure the volume is consistent between content programming, and also reduce louder sounds for night time listening or boost quieter sound for noisy environments. This may be applied on the streaming source end or the listener end. 

We may have some control over this and not always know. Many devices have built in options. Apple TV has “Reduce Loud Sounds” and Roku has “Leveling” and “Night” modes. You can also find these kinds of settings in home theater receivers and sound bars. When switched on, these controls will have an impact on how the original mix was intended to be heard. It can enhance or ruin the listening experience depending on how the software interprets the source sound. So don’t forget to check in the audio settings to ensure you’re hearing the mix the way you want to.

In Summary

The problems that arose out of the playback of our film deliverables did not come from the original sound mix, but rather when it got squeezed through software and output at the wrong level through streaming on the source end. We can only do so much and are at the mercy of the delivery platform. 

As time goes on, hopefully the audio loudness software integrated into these platforms will be able to better adapt to changing dynamic levels from source content. We will continue to observe these trends, and acclimate our mixes to be ready for what comes next. 

To learn more about how we can help prepare your next project for broadcast and streaming, contact us.