Adjusting Analog Audio Levels for Capture

Along with the color bars at the beginning of your tape, there may also be a reference audio tone, usually at 1 kilohertz (kHz), set to 0 decibels (dB) on an analog meter. If you’re capturing from a master tape in which the audio has already been mixed, all of the audio levels should have been mixed relative to the level of this reference tone.

The goal is to affect the audio signal as little as possible when you capture audio to your scratch disk. It’s better to make audio level adjustments after you capture, because level changes you make in Final Cut Pro are nondestructive. You can always return to the original audio levels if necessary.

If you’re capturing audio from a tape recorded on location, reference tone at the beginning of the tape is a good starting point for setting your levels, but chances are that the audio will vary from shot to shot. In this case, it is important to adjust the audio gain on your audio interface to record the best possible audio levels. You should set levels to avoid clipping the audio during capture. Clipped audio has a crackling, distorted sound that is unacceptable for professional work. Sometimes one setting will work for every clip on your tape. Other times, you may find yourself adjusting the audio levels for each clip. It all depends on how widely the audio levels vary on a given tape.

Note: When capturing digital audio, the gain level is already set and cannot be modified.

To adjust the audio gain levels before capturing analog audio
  1. In the Log and Capture window, click the Clip Settings tab.

  2. Do one of the following:

    • Cue your tape to the reference tone recorded at the beginning of the tape, if you’re recording from a premixed tape that includes a reference tone.

    • Cue your tape to the clip with the loudest audio signal of all the clips you want to capture on that tape.

  3. Play back your tape.

  4. Verify that the levels coming from your deck match the audio input meters on your audio interface.

  5. In the Clip Settings tab of the Log and Capture window, turn on the audio channels that you want to capture audio from.

  6. Adjust the gain on each audio input of your audio interface so that the Final Cut Pro audio meters are equivalent to the meters on your deck.

Tone on analog media formats is usually set to 0 dB (analog). You need to choose an equivalent digital level on the Final Cut Pro audio meters. The level you choose is dependent on the bit depth you are using to capture your audio, as well as how much dynamic range your audio has:

For more information about bit depth, see Audio Fundamentals.

Important: To avoid distortion, do not allow audio levels to go higher than 0 dBFS on the Final Cut Pro audio meters.

About Audio Peaks

When you capture audio, clipping occurs if any part of the audio signal goes over 0 dBFS. Because 0 dBFS is the maximum digital level possible, all levels that would have been above 0 dBFS are set to the maximum audio level, causing clipping. Due to the nature of digital audio recording, such clipped audio typically results in a crackly, brittle-sounding clip that is unsuitable for use. All occurrences of clipped audio appear as 0 dBFS peaks. Excessive peaks indicate that your audio was recorded at unsuitable levels.

Final Cut Pro alerts you when an audio channel is peaking by lighting up its peak indicator in the Clip Settings tab of the Log and Capture window. If the peak indicator is lit, you should reduce the gain for that channel on your audio interface.

If you have already captured a clip and it has peaks in the audio, you can either recapture the audio at a better level or edit the audio appropriately to avoid the peaks. You can use the Mark Audio Peaks command to identify audio peaks in clips or sequences. It’s then up to you to decide whether to avoid using those sections of audio or rerecord them. For detailed information about the Mark Audio Peaks command, see Evaluating Levels with Audio Meters.