We had a live orchestra in our school whereby we had to record it in camera?

The inputs of vocals and musical instruments were taken in a Yamaha mixer and the output from th mixer was given to the camera (Sony PD 170). After recording when it was played, the audio was very loud , and it just got dstorted and nothing cold be heard clearly. What are the adjustments required to get a perfect sound in the camera ? How can the recorded audio be rectifed ? I use Avid Express DV software for editing. Any audio software that could clean the audio?