In Premiere Pro, you create clips by importing files, duplicating clips, or making subclips. You create a clip instance by using a clip in a sequence.
In Premiere Pro, a clip points to a source file. Trimming a clip, or editing it in any way, does not affect the source file. For example, if you import a 30-minute file into Premiere Pro, you create a 30-minute clip that points to that source file. If you trim the clip to a five-minute duration, the 30-minute source file remains on your hard disk, but the clip refers only to a five-minute section of it. Premiere Pro stores information about clips in clip metadata fields in project files, but stores information about source files in XMP metadata fields.
You can trim source clips, clip instances, subclips, or duplicate clips. You can trim all types of clips in sequences in much the same way. The clip types differ in the following ways:
Source (master) clip
The clip originally imported into the Project panel. It is listed in the Project panel only once by default. If you delete a source clip from the Project panel, all of its instances are also deleted.
A dependent reference to a source clip, used in a sequence. Each time you add a clip to a sequence, you create another instance of the clip. A clip instance uses the name and source file reference used by its source clip. While clip instances are not listed in the Project panel, they are differentiated in the Source Monitor menu if you open instances there. The Source Monitor menu lists instances by name, sequence name, and In point.
A section of a master clip that references the master clip’s media file. Use subclips to reference discreet sections of long master clips. (See Creating subclips.)
An independent copy of a source clip, which you create manually using the Edit > Duplicate command. You can also create a duplicate clip by importing the same file more than once. Unlike a clip instance, a duplicate clip maintains its own reference to the original clip’s source file on disk and exists as an additional clip in the Project panel. Premiere Pro does not delete a duplicate clip when you delete its original from the Project panel. Master and duplicate clips can be renamed independently.
Franklin McMahon explains how to use subclips in this video from Layers Magazine.
For more details, see Andrew Devis’ tutorial, “Subclips: What? Why? How?”
See also Andrew Devis’ tutorials, “Understanding the Source Panel tools.”
A subclip is a section of a master (source) clip that you want to edit and manage separately in your project. You can use subclips to organize long media files.
You work with subclips in a Timeline panel as you do with master clips. Trimming and editing a subclip is constrained by its start and end points. However, you can set new In and Out points for a subclip, as long as they fall between the original In and Out points you set for the subclip when you create it from the master clip.
Subclips reference the master clip’s media file. If you delete a master clip or take it offline and keep its media on disk, the subclip and its instance remain online. If you take the original media off disk, the subclip and its instances go offline. If you relink a master clip, its subclips remain linked to the original media.
If you recapture or relink a subclip, it becomes a master clip, and all ties to the original media are broken. The recaptured media includes the subclip’s referenced portion of the media only. Any instances of the subclip are relinked to the recaptured media.
You cannot make the following types of clips into subclips:
Selections of multiple clips
Titles, still images, synthetic clips
To use a master clip and its subclips in another project, import the project that contains the clips.
You can create a subclip from any merged clip in the same way you would any other subclip. The Master Clip Start timecode is the earliest timecode of the component clips. The Master Clip End timecode is the latest timecode of the component clips. The Convert to Master Clip check box is disabled.
You can create a subclip from source clips or other subclips that are made up from a single media file.
You can also convert a master clip into a subclip by selecting the source clip in the Project panel or Source Monitor, choosing Clip > Edit Subclip, and setting media start and end times for the subclip.
If you select an instance of a subclip in the Project panel, you cannot set new Start and End points that lie within the instance Start and End points. This limit prevents losing frames that are used in the sequence.