What is Dynamic Compression?
Dynamic compression refers to reducing the difference between the loudest and quietest points in a recording. While it's similarly named to regular-old file compression, they are not related.
When we talk about a recording's dynamic range, we're talking about the range of volumes – from the quietest points in the recording (that is, the quietest point where there's actually something audible, and not simply silence), to the loudest. A recording with a large dynamic range has a large range between the quietest points and the loudest points, and a recording with a small dynamic range has little difference between the loud and quiet points.
Dynamic compression is a processing step that you can run on a recording to reduce the overall dynamic range of the recording.
Why Might I Want Dynamic Compression?
Dynamic compression reduces the volume of the loudest points of a recording, and increases the volume of the quietest points, resulting in a recording with a more even overall volume level throughout. While dynamic variability can be used to great effect on purpose (think of a storyteller getting very quiet to draw you in), unintended dynamic range can be frustrating. We've all had the experience of turning up the volume to hear something quiet, only to have our ears blown out when the recording suddenly gets loud again.
Dynamic compression is often the final step of a recording mix process, and when well applied, results in a mix that sounds professional and even, and is easy for your listener to enjoy without having to make volume adjustments throughout.
Humans naturally introduce dynamic variability while they talk, and recording with multiple people will often include more variability between speakers. While it's not a perfect solution, dynamic compression may also be able to salvage a recording where one participant was recorded so much more quietly than the others that simple volume adjustments are unable to get the users to a relatively consistent volume level with each other. That said, because this will likely operate by boosting the quiet user's volume significantly, it may up the baseline noise level in their recording and should only be used as a last resort.
Similarly, because dynamic compression operates (in part) by boosting volume levels, on some recordings it could produce an undesireable end result, particularly with recordings that are noisy to begin with.
How Does Cast's Dynamic Compression Work?
We have developed Cast's dynamic compression to work well across a wide range of possible mixing scenarios, by tuning various parameters until we've ended up at a result that we feel works well in many scenarios. When mixing in Cast's Editor, you can select dynamic compression as an option and you'll hear it in your mix. Your best guide here is your own ears – run a test mix with dynamic compression enabled and see how it compares to a mix without it.