•DVD authoring describes the process of creating a DVD video that can be played on a DVD player. DVD authoring software must conform to the specifications set by the DVD Forum group in 1995. The specifications are complicated due to the number of companies that were involved in creating them.

Audio and video call for customized methods of compression. Engineers and mathematicians have tried a number of solutions for tackling this problem.

There is a complex balance between the video quality, the quantity of the data needed to represent it, also known as the bit rate, the complexity of the encoding and decoding algorithms, robustness to data losses and errors, ease of editing, random access, the state of the art of compression algorithm design, end-to-end delay, and a number of other factors.

You may find that you are unable to play clips from the timeline without rendering, even though it may be a cuts only edit with no filters or audio mixing applied. This is because the Sequence Settings are incorrectly set. This article discusses how to correct this in the Sequence Settings Panel.

A mistake that new users frequently make is to load a number of video clips into a new sequence which use a codec, frame rate, or frame size that does not match the preset Sequence Settings. For example, if you install Final Cut Pro and select DV as the default setting, then try to go through the tutorial using the supplied clips, you will find that Final Cut Pro will want to render every clip in the sequence before playing from the timeline. This is because the clips in the tutorial are compressed using the Software Preset, while in this situation the Sequence Settings by default are set to DV-NTSC.

The Sequence Settings define which clips will play from the Timeline without rendering. Since you can mix and match virtually any sort of Quicktime video clip in any sequence you choose, (for example, Animation clips with DV clips) it is important to tell Final Cut Pro which clips do not need rendering and which clips do.

You can  find out if your clip settings do not match your sequence settings in one of two ways :

1. Select that clip in the Browser and choose Clip from the Analyze Movie sub-menu under the Tools menu shown in Figure 1.

Figure 1 The Tools>Analyze Movie>Clip menu

2. Use the contextual menu in the Browser (Control+click) to select the Item Properties command shown in Figure 2.

Figure 2 The Browser contextual menu showing the Item Properties command

Figure 3 The resulting Item Properties window. Properties used in the Sequence Settings box are highlighted in red.

If the clip settings do not match the currently applied Sequence Settings, then you need only open the Sequence Settings panel, select the preset that matches the type of video material you will be editing from the lower left-hand pop-up menu, and press the Load Preset button.

Figure 4 Selecting the Software Preset in order to go through the Tutorial

If you wish to edit using custom material, perhaps with a different frame size or Quicktime codec, you can easily create a new preset by following these steps:

1. Open Sequence Settings from the Sequence menu.

2. Set the Video Codec, Audio Sample Rate, Frame Size, Field Dominance, and Pixel Aspect Ratio that match those of your video clips.

3. Click the Save as New Preset button.

Figure 5 The Save as New Preset button

4. Give your new preset a name and click Save.

The Sequence Settings box will close. To actually use this new setting, you must reopen the Sequence Settings box, select the new setting from the lower left-hand pop-up menu, and click the Load Preset button.

Note: The timebase can not be changed once a sequence has been created. To change the timebase, you must first delete all sequences currently in the browser.