Here are a few things to think about when you are mixing your sound for video.
Post-production in film and video is not just composed of video editing, motion graphics, color correction, and DVD authoring. Sound mixing is a central part of this because if the audio is not balanced well it will not allow the rest of the film to actually flow as a cohesive piece. This sound mixing will allow you to take full control over your film, allowing the multiple tracks of recorded sound to come together in a mesh that will replicate the story space you are intending. If you have a full editing suite at your disposal for sound editing you will find that doing quick and easy audio mixes are not as hard as they would seem. Here is a look at how to do audio mixing for a basic audio mix on your video project.
Home Audio Mixing Stations
Many people who are learning how to do audio mixing successfully want to know how to do it on a basic home audio mixing station. Though a home audio mixing station is often used and can be useful for much of the practical sound mixing, you cannot do a full audio mix successfully on a simple system. The most recent version of Pro Tools is able to work without hardware, but this does not mean that it is going to be useful without a mixing board and a high-end computer to support it. You will also need to have quality speakers, preferably both nearfield and farfield to get a duality in the sound. The room itself will have to be dedicated to the sound mixing and will have to be soundproofed effectively, more for the quality of audio playback to the person mixing rather than the bleed through. On top of all this, you are going to need an independent television monitor for the video playback for syncing to the audio. All of this presents a fairly elaborate package that is more than a few thousand dollars, but going to be the baseline for complete audio mixing. If you want to learn how to do audio mixing on a simple system, you are going to have to give up a professional mix in general, though you can still bring it up to an 80% mark if you know what you are doing.
One of the primary focuses of audio mixing is dealing with the levels of the audio. When you are filming you will notice that, not just in a given scene, but different takes or even within a single take the audio will vary a great deal. This is a problem when you edit them together, and once scenes have been cut together and sent to the sound mixer you will notice that there is a lot of unevenness in the audio. It is up to you to adjust each clip so that it will flow together and not be jarring, unless you would want it to be. This does not mean that you are going to keep the levels on each audio clip the same, but relatively even so that they seem natural in their highs and lows. Since there will likely be multiple tracks of audio when it comes in, you will want to make sure you adjust the levels on each one, likely keeping some at a different consistency than others. For example, dialogue may be generally higher than background sound or music. This is especially true in documentary production where there is all different types of footage being put together in a collage.
One of the other main purpose of doing sound mixing is to add audio effects. These are usually done along with video to repair problems or make the audio recorded sound more appropriate to the story space. There is no definite way to apply audio effects greatly, but what you can do is try out several on your clips and learn the basic idea of what each type of audio effect does so when problems occur during your mix you know where to turn to first. For example, a low pass filter will allow low tones to pass through the filter and will take out the high ones. This is great if you have background noise at a high pitch and need it to be removed. There are a lot of others, such as Pro Tool's TL Space, which will change the character of the sound to make it come across as if it was in a specific location. All of these are used to be unobtrusive in the sound mix, which is not always the same with video effects.
Source: Author's own experience.