To create a virtual clip, use the MVCP command CMK. The syntax and arguments for CMK and the related command COPN are described briefly as follows:

CMK clip-name format-name
COPN clip-name

CMK creates a fetal clip. A fetal clip is not visible in the clip cache nor can it be used for playout until clip segments are assigned using the CUPS command. A fetal clip has minimal state and serves as the foundation for vclip editing operations. The COPN command opens virtual or non-virtual clips for subsequent edit operations.

It is important to note that a fetal virtual clip cannot be deleted unless it contains at least one segment and has been previously closed, thus promoting it out of the fetal state into the clip cache. A fetal clip without one segment is termed incomplete; VST cannot process incomplete fetal clips. Attempted deletion of an incomplete fetal clip leaves an unmanageable entry, which cannot be cleared without a VST restart. Attempts to reuse a deleted, incomplete fetal clip will fail.

To create a non-virtual clip, use the CBLD command. This command physically copies the referenced segments from a virtual clip into a continous, non-virtual clip and assigns an arbitrary timecode for a non-virtual clip start. The syntax of the CBLD command is as follows:

CBLD clip-name new-clip [start]

To save, close, or remove a virtual clip, use the following MVCP commands, respectively:

CSAV [clip-name]
CCLS [clip-name]
CRM  [clip-name]

clip-name

Specifies the name of the clip to save, close, or remove. If clip-name is not specified, the most recently created or opened clip is saved, closed, or removed. Note: CSAV, CCLS, and CRM work with virtual and non-virtual clips.

The CUPS (update) command, defined as follows, adds segments to vclips:

CUPS clip-name src-op dest-op trk-mask in out src-clip src-trk-mask src-in src-out

Figure 6-2 illustrates some of these arguments.

Figure 6-2. CUPS Arguments

The interval between src-in and src-out must equal the interval between in and out; otherwise, an error is returned. If you supply only one of these intervals, CUPS automatically makes the other interval equal to it.

Using the CUPS command repeatedly enables you to populate your virtual clip with segments.

When a segment from a source clip is removed (FRM), the segments before and after the copied segment are joined. The FCL operation is not supported by the PCI-VIDAUD-MSB-B codec.

Figure 6-3. Copying Versus Linking; Where Segment Data is Stored

To display pertinent information about the segments in a vclip, use the CSLS command:

CSLS [ clip-name [ track-mask [ in [ out ]]]]

Use the in and out arguments to display information about segments in a subsection of the vclip.

For each segment in a vclip, CSLS displays a line of information in the following format:

trk in out clip-name src-trk src-clip src-in src-out

To clear or remove segments in a virtual clip based on fixed-format clip content (DVCPRO, DVCPRO 50, DVCAM, or DV (16-bit/48 Khz audio only)), use the following MVCP commands, respectively:

CSRM clip-name track-mask timecode

Segment clearing using the CSCL command is not supported by the PCI-VIDAUD-MSB-B codec. When a segment from a specified clip is removed (CSRM), the segments before and after the specified segment appear contiguous, as shown in Figure 6-4.

Figure 6-4. Clearing Versus Removing Segments

The CFNW command inserts empty (black and silent) frames into a clip based on fixed-format clip content (DVCPRO, DVCPRO 50, DVCAM, or DV (16-bit/48 Khz audio only)). The syntax of the CFNW command is as follows:

CFNW clip-name track-mask in out

To use CFNW, the specified clip must have previously been opened or created using COPN or CMK, respectively, during the current MVCP session.