Premiere Pro provides a method for synchronizing audio and video called Merge Clips. This function streamlines the process by which users can sync audio and video which have been recorded separately (a process sometimes called double-system recording). You can select a video clip and sync it with up to 16 channels of audio by using the Merge Clips command. Clips which make up the merged clip are referred to as component clips.

Clips can be merged by group selecting them in the either the Project panel or the Timeline. The Merge Clips command may be invoked via either the Clip menu or a contextual menu. It is a contextual command, so more than one clip must be selected in order to enable it.

You can merge one or multiple audio clips to a single video or AV clip. The total number of audio tracks permissable in a merged clip is 16, including any combination of mono, stereo or surround 5.1 clips. A single mono clip counts as one track, a single stereo counts as two tracks, a 5.1 clip counts as six tracks.

To merge clips in the Project panel, do the following:

1. Select the video clip you wish to merge audio clips to. Note that you can have only one video clip in any merged clip.
2. Shift or Control-click (Command-click for Mac OS) to select the audio-only clips you wish to merge with the video clip.
3. Do one of the following:

• Choose Clip > Merge Clips
• Right-click (Control-click for Mac OS), and then choose Merge Clips from the shortcut menu.

The Merge Clips dialog box launches. Choose from one of the following options for the point of synchronization:

• Based on the In point: For locating sync based on the In point, at the clap of the slate, for example.
• Based on the Out point: For locating sync based on the Out point, at the clap of the tail slate, for example.
• Based on matching timecode: For locating sync based on common timecode between the clips.
• Based on clip markers: For locating a sync point based on a numbered clip marker in the middle of the shot. This function is disabled unless all component clips have at least one numbered marker.

Click OK. Your merged clip will now appear in the Project panel, with a name that matches the video clip, or the top-most selected audio clip (based on current sort order in the bin) if there is no video. “- Merged” is appended to the end of the new merged clip’s name. Users may rename this item, if necessary.

Merge clips in the Timeline panel

To merge clips in the Timeline panel, do the following:

1. Select the clips (if they are not already selected), and then do one of the following:

• Drag the component clips into the Project panel.
• Choose Clip > Merge Clips.
  

The Merge Clips dialog box launches.

2. Click OK. Your merged clip will now appear in the Project panel.

Synchronize clips in the Timeline panel

Synchronizing clips aligns multiple clips in the Timeline panel. After synchronizing the clips, you can create a merged clip.

To synchronize clips in the Timeline panel, first edit the clips into the Timeline panel, and then do one of the following:

• Align the clips manually by dragging them into place until they are synchronized.
• Align the clips using the Synchronize function. To do so, do the following:

1. Select the clips you wish to synchronize.
2. Choose Clip > Synchronize.
   

The Synchronize dialog box launches. Choose from one of the following options for the point of synchronization:

• Based on the Clip Start
• Based on the Clip End
• Based on matching timecode
• Based on clip markers

Click OK. Your clips are now synchronized.

Editing with merged clips

In general, working with merged clips is much like working with any other clip. There are some workflow differences worth noting, however.

Editing merged clips with gaps into the Timeline

Merging clips affects their behavior when you're editing them into the timeline: specifically, if the clips contain “gaps” in their component structure.

When there is another component clip available If an In or Out point is marked in a gap in the audio or video, and there is another component clip available above or below that gap, Premiere Pro uses a track for the gap when you're adding the merged clip to the Timeline.

When no component clip is available Note that it is possible to merge audio and video and have places in the merged clip where there is no other component clip in the gap. If you have marked an In or Out point in a gap, you'll receive a warning that states, “Invalid edit. No media present in source clip’s marked In/Out range” when you try to add the merged clip to the Timeline. The “no drop” icon will appear if you attempt to drag and drop the merged clip into the Timeline.

Trimming merged clips

Trimming merged clips is much like trimming any other clip, with the following exceptions:

• During trimming, the trim is applied equally to component clips, preserving any offsets.
• To trim the edge of a single component clip, users can temporarily break sync by holding down the Alt/Option modifier while dragging.
• When trimming individual component clips, snapping occurs at the ends of other component when snapping is on.
• Normal trimming rules apply; a merged clip can only be trimmed to the point where there is at least one frame remaining in any of the component clips.

Merged clips and the Metadata panel

When a merged clip is created, the metadata for each of the component clips is copied into the Metadata panel. There are some differences for displaying metadata for a merged clip. They are as follows:

Viewing metadata You can view the metadata a single component clip. To view the metadata for a component clip, choose the clip name from the File popup menu. Its metadata will appear in the metadata panel.

Entering metadata You can enter metadata to a component clip or for the entire merged clip.

• Set the File popup menu to the component clip you wish, and then enter metadata for the clip.
• Set the File popup menu to All Files, and then enter metadata for the merged clip. Any data entered into a property will be entered into the XMP for each of the component files that make up the merged clip.

Use timecode from an audio master clip to create a merged clip  

You can use the timecode from an audio master clip when you create a merged clip. You can also choose to omit the source camera audio when creating a merged clip.

Do the following:

1. Select the video clip and the audio clip that contains timecode.
2. Choose Clip > Merge Clips.
3. In the Merge Clips dialog box, do one of the following:

• To use timecode from an audio master clip to create a merged clip, select the “Use Audio Timecode from Clip” check box. Then choose the audio track you want to synchronize video with from the pop-up menu.
• To delete source camera audio from a clip, sele ct the “Remove Audio from AV Clip” checkbox.

      4.  Click OK.

Merged Clips limitations

• The Replace Footage command does not work.
• Attaching Adobe Story scripts, and then analyzing speech to text is not supported.
  
  Note: If you attach an Adobe Story script to an audio clip prior to merging, then you can analyze speech to text after merging them. Select either “All Files or the audio clip containing the script from the File pop-up menu in the Metadata panel, and then click the Analyze button.
  
  
• Full audio channel mapping control in the merged clip is not supported.
• Merged clip audio results in mono track audio only. Final Cut Pro XML and AAF interchange formats are not supported.
• Auto-sync using audio waveforms, free-run timecode, time-of-day timecode, AUX timecode, or separate audio timecode is not supported.
• Reveal in Adobe Bridge is not supported.
• Once created, the merged clip cannot be re-synchronized, or adjusted. To re-snyc or adjust your clips, make a new merged clip.
• Adjusting contents of a merged clip is not supported. However, if a particular component clip is deleted, the merged clip may be relinked.
• Merged clips or parts of previously merged clips can't be used to remerge or make a new merged clip. Only component clips may be used to create a merged clip.