Through The Sound Recordist's Eyes
Audiences can and do forgive poor-quality video, but have a harder time accepting poor sound. For this reason, most sound techs prefer to work onsite when and where possible. Not only does this reduce post-production time, effort and expense, but it helps achieve a more natural sound during the actual shoot. However, sometimes problems crop up: poor sound adjustment, ambient noise that cannot be corrected for or a simple lack of good equipment.
In these cases, the production sound mixer may have to go back in post-production and make some decisions. If the video quality is adequate, the sound can often be manipulated or worked with to bring it into parity with the video using mixer adjustment and computer programs such as CEDAR or Algorithmix. However, these programs cannot fix everything. If there is an unacceptable level of distortion, the mixer may be able to repair the audio by adjusting the equalizer or reverberation settings. This is not a solution to every problem, and it may not always be possible to "dampen" distortion, which is why having the sound recordist on board from the beginning is the best way to avoid problems before they begin.
Think back to when you were a kid and tried to watch scrambled cable channels. While you could occasionally make out clear images, your ears were doing most of the work. Similarly, the sound recordist has to adjust and clean up the sound so it will compensate for botched video. This is always easier to accomplish onsite, but sometimes time and budget factors prohibit it.
Fixing Poor Video/Sound Combination
The recordist cannot affect or help the quality of the video, but can make the sound crisper and sharper. When post-production is necessary, ADR, or Automatic Dialog Replacement, has become the go-to option over looping, where an actor is required to synchronize in-studio voiceovers with the on-screen action. ADR's popularity stems from the fact it is cheaper relative to looping, but still tacks more money onto the post-production cost.The better and clearer the sound is from the start, the less post-production tweaking it will need. Sound recordists are not miracle workers and even with modern sound correction equipment and software, what they can do is limited by what they are initially given to work with. Still, veterans can often take bad footage and make it better on the strength of the sound alone. Professional sound recordists know what can and cannot be done, and can tell you what options exist to help fix poor sound with your video and assess their feasibility within the context of your budget.