Beth Cataldo, March 29, 2007

Adding Markers in DVDSP

Markers create points in a track that you can directly navigate to. Each track in your project can hold up to 256 markers. You can have up to 99 markers on each track. The first Marker of each track is locked onto the first frame of the movie.

Markers can only be put on I-Frames (Reference Frames created when encoding into MPEG-2. They are the beginning of a Group of Pictures (GOP)). This means that you can't be precise in DVDSP. Usually, you can put a marker on every 15 frames. If you need to put a precise marker on your video, use FCP.

(What is an I-Frame? [Definition taken from WiFi Planet.com]: I-frame is short for intraframe, a video compression method used by the MPEG standard. In a motion sequence, individual frames of pictures are grouped together (called a group of pictures, or GOP) and played back so that the viewer registers the video’s spatial motion. Also called a keyframe, an I-frame is a single frame of digital content that the compressor examines independent of the frames that precede and follow it and stores all of the data needed to display that frame. Typically, a I-frames are interspersed with P-frames and B-frames in a compressed video. The more I-frames that are contained, the better quality the video will be; however, I-frames contain the most amount of bits and therefore take up more space on the storage medium.)

If you want to use DVDSP for your markers:

1. Go to the Timeline. You will be able to scrub through your video and add new markers.

2. To create a Marker, place your Playhead where you want a Marker and either click in the Marker area at the top of the Timeline or hit the "M" key.

3. A new Marker is created on the Timeline. Remember that Markers can only be placed on I-frames (about every 15 frames), which are also called GOP headers.

4. You can reposition the Marker by dragging the top of it to the place where you want it. You can’t place Markers precisely in DVDSP because of this. When you place a Marker in a video stream, it may appear to move when you jump to that Marker. This is because DVDSP links to the closest I-frame.

5. Name the Marker by clicking inside the Inspector box.

6. You can delete markers from the Timeline by choosing the top of the Marker and then hitting the deleting key.

Once you’ve created a marker, it will appear in your project’s Target drop-down menu so you can link to a Marker from any button. You can rename Markers with names that make sense to you.

That way, you won’t have to jump back to see which marker you want to jump to.

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