Finishing Audio and Video

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During the editing process, you often deal with audio and video from different sources that were recorded at different levels and under different conditions. Perhaps you were given a narration recorded in a studio and ambient sound recorded in the field. Or you worked with some footage that was shot indoors at night and some that was shot outdoors in the bright sunlight. After you've made your creative decisions and finished editing your sequence, you can turn your attention to refining the video and audio so all the clips will work together as a whole.

The video and audio levels should not be too high or too low. As you know, audio levels that are too high can become distorted. And high video levels may result in video that is not broadcast safe, meaning it exceeds the limits of the FCC standards.

Detecting Audio Peaks

When adjusting the audio level of your sequence, the one absolute rule is never to allow the audio to peak over 0 dB. Final Cut Pro can help you pinpoint exactly where the audio is peaking in your sequence by placing a marker in the Timeline at each peak.

1.

In the Timeline, play the Racing Promo sequence, and watch the audio meters to see if there are any peaks in the sequence. You can also open the Audio Mixer and look at the audio levels on the Master fader.

When the audio peaks in the Timeline, the red clipping indicator lights up on one or both audio meters, depending on which track peaked. The indicators stay red until you stop playing the sequence. Although these indicators tell you there was an audio peak, they don't pinpoint exactly where in the sequence it occurred.

2.

In the Timeline, deselect all clips by clicking in the empty gray area of the Timeline or pressing Shift-Cmd-A. Choose Mark > Audio Peaks > Mark.

A progress bar appears while Final Cut Pro examines the sequence.

When the detection is complete, markers are placed in the Timeline ruler area wherever the audio peaks occur in the sequence. If the peak is sustained for more than an instant, a long marker or marker with a duration appears over the clip to indicate the length of the peaking audio.

NOTE

When the playhead is over an audio peak marker, Audio Peak appears as an overlay in the Canvas to identify it.

3.

Move the playhead over the first audio peak marker, and zoom in to get a better view.

Audio meters reflect the levels of the combined audio tracks in the sequence. You will have to judge which individual tracks are causing the peaking. Since the music and sound effects are very low at this location, it's most likely that the A1 and A2 voice-over clips are the problem.

4.

Move the playhead over the next group of audio peak markers.

Here again, the VO clip is causing the sound to peak.

5.

Select the JM what you see clip" under the first two audio peak markers. Cmd-click the JM what you see clip under the next two markers to add it to this selection.

NOTE

You can toggle on clip overlays if you want to view the volume level lines on the clips in the Timeline.

6.

Choose Modify > Levels.

A Gain Adjust window opens. You can use this window to adjust current levels for a single clip or a group of clips. Gain adjustments that you make in this window can be relative or absolute. Making a relative adjustment changes the current level of the selected clips by the amount you enter and maintains any keyframes those clips may contain. Making an absolute adjustment removes any keyframes and resets the audio to a specific level.

NOTE

If you select a video clip and choose Modify > Levels, an Opacity Adjust window will appear, allowing you to adjust the opacity level of the clip.

7.

In the Gain Adjust window, in the Adjust Gain By field, enter 3 dB, and leave the Make Changes option set to Relative. Click OK. Watch the audio meters as you play through these two clips.

These clips no longer cause the audio to peak.

8.

If there are any other peak markers in the sequence, select the clip and adjust its levels using the Gain Adjust window.

TIP

A good time to use the Absolute option in the Gain Adjust window is when you have changed the audio level of one or more clips and want to return them to their original 0 dB level, or to another specific level. You would enter 0, or other number, in the Adjust Gain By field and choose Absolute from the Make Changes pop-up. This option removes all keyframes.

9.

To clear the audio peak markers from the Timeline, choose Mark > Audio Peaks > Clear, or press Ctrl-~ (tilde key).

TIP

If you've changed the peak levels and want to reassess whether there are still audio peaks, choose Mark > Audio Peaks > Mark again. Remember to deselect all clips before choosing this option.

Adjusting Video Levels for Broadcast

One of the most common problems with video levels is that sometimes the whites of an image, or the luminance levels, are too bright. This can be a serious consideration, because the FCC mandates that no video should be broadcast with a luminance level over 100 IRE, which is considered to be broadcast safe. (IRE is a unit of measurement in video that was named for the organization that created it the Institute of Radio Engineers.) If video does go over 100 IRE, the video level is clipped during broadcast, similar to the way audio is clipped when it peaks over 0 dB. Some networks or facilities may reject the tape and choose not to air it at all.

To prepare the video portion of your sequence for output, you will need to monitor the luminance levels of your clips, then lower those that are too bright. Final Cut Pro has a tool called Range Check that will check both the luma and chroma of a clip to determine whether they are within an acceptable broadcast range. When you find clips that are not within broadcast specifications, you can apply the Broadcast Safe filter to correct them. Use the Video Scopes tool as a reference when viewing video levels.

1.

In the Timeline, move the playhead to the beginning of the biker down clip, the sixth video clip from the end of the sequence.

2.

Open the Video Scopes tool by choosing Tools > Video Scopes. When the Tool Bench window appears with the Video Scopes tab, position the window over the Browser.

3.

In the Video Scopes tab, click the Layout pop-up menu and choose Waveform.

The Waveform Monitor enables you to see the luminance values of the current frame. Broadcast standards specify a maximum luminance level for any video. This is represented in the Waveform Monitor as 100%.

4.

Move the pointer up and down over the Waveform Monitor.

A yellow horizontal line follows the movement of the pointer, and a number in the upper-right corner displays the luma percentage of the current pointer location in the scope.

5.

To check the luma level of the current clip, make the Timeline active and choose View > Range Check > Excess Luma, or press Ctrl-Z.

When you toggle on Range Check, each clip in the sequence will appear with one of three symbols indicating whether the luminance level of that clip is or is not within legal range for broadcast use. For the current clip, agreen circle and a checkmark appear in the Canvas, indicating that the luminance levels for that frame are broadcast safe and below 90 percent.

6.

Move the playhead to the beginning of the second clip in the sequence, the BS helmet on clip.

An in-range icon appears with a checkmark and an upward arrow, indicating that some luma levels are between 90 and 100 percent. The affected areas are indicated by green zebra stripes. Although it's reaching the upper limit, this is still acceptable video.

7.

Press the down arrow to move the playhead to the next video clip, the DS prep track clip.

A yellow warning icon appears, indicating that some luminance levels are above 100 percent. The red zebra stripes show the areas of the image that are above 100 percent. The waveform shows how much the luminance values exceed 100 percent.

8.

Select the DS prep track clip, and choose Effects > Video Filters > Color Correction > Broadcast Safe. Double-click the clip to open it in the Viewer, and click the Filters tab to see the filter parameters.

With the Broadcast Safe filter added to this clip, the red zebra stripes in the Canvas turn to green, and the Waveform Monitor shows that the luminance levels have been clipped at 100 percent.

NOTE

If you suspect that some of your color levels are too intense, you can choose View > Range Check > Excess Chroma and view the Vectorscope to identify any problem areas.

Project Practice

To continue fine-tuning the video, step through this sequence and practice applying the Broadcast Safe filter to the clips that need it. For more practice, open the Team Story sequence from the Browser and check it for audio peaks and video levels. This video was shot outdoors in bright daylight, so you may find that several clips are out of the broadcast-safe range.

When you've finished practicing, close the Tool Bench window and choose View > Range Check > Off.

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    Apple Pro Training Series. Final Cut Pro 5
    Apple Pro Training Series: Final Cut Pro 5
    ISBN: 0321334817
    EAN: 2147483647
    Year: 2005
    Pages: 235
    Authors: Diana Weynand

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