Your favorite band is playing live and you capture your favorite song on your phone. Later after the show you remember how good it was and playback your stored video. The video looks good enough but the sound is just a bunch of noise and speaker pops. Ever wonder why? The microphone that comes with your phone is a very cheap and limited piece of equipment. Even with an expensive microphone it would be difficult to capture a live performances audio program because of the sound pressure that is generated by the stacks of speakers used in the sound reinforcement system.
This can cause your small microphone to bottom and to top out causing unwanted transients at almost a constant rate, not to mention you are recording all of the signal present in mono, which compounds the problem. Modern sound reinforcement systems are capable of producing concussive shock waves and are used to fill an arena with sound pressure, enough for the entire crowd to enjoy. If you want to capture a live performance get a professional camera and capture the audio from the soundboard/mixer. This allows you to capture what the engineer is hearing from either the monitor system on stage or the sound reinforcement system pointed toward the crowd. This signal is not so strong that it will cause clips because it is before the amplification and audio reinforcement system.
If you can gain access to the final mix you can then synchronize the audio from the mixing console with the live action of the video. Now you have the equivalent of a professional video. You should have clear pictures and the audio should be loud enough to be dynamic yet not cause clipping in your editor or when released to be played back on other devices. Sound pressure plays a big role when capturing audio. You wouldn’t want to simply mic the sound reinforcement system because it will cause the mic to perform very poorly. Always go with the source signal at the mixer when possible. This will ensure that your overall balance and level of audio are well within the play back system range and should provide a considerably higher quality of audio for the final project.