What function does the splice-in command perform in a timeline?

The splice-in command plays a vital role in timeline editing by adding additional material into the existing sequence. This function allows editors to insert clips at specific points in a timeline without overwriting or permanently altering any of the existing content. When using splice-in, the current sequence is expanded to accommodate the new material being added, making it a valuable tool for enhancing the overall narrative without losing any previously established edits.

In the context of video or audio editing, adding more material can significantly enrich the composition, offering new perspectives and elements to the project. It's particularly useful when integrating additional footage that complements the storyline or enhances the audio track without disrupting the flow of the existing timeline.

The other options do not accurately describe the function of splice-in. For instance, replacing existing material would imply removing something that was already there, which is not what splice-in does. Selecting the entire clip or removing material pertains to different editing commands that focus on managing existing content rather than integrating new content.