About Dual-Layer Discs

Dual-layer discs present several challenges:

Dual-layer discs allow you to place nearly twice as much content on a single disc side, but there is a downside to this method: At some point, the DVD player must switch from reading the first layer to reading the second layer. Switching between layers requires the player’s laser to refocus and then locate the sector at which to start playing. During this time, the video image freezes, which may confuse viewers or make them think the disc is defective.

There are two things you can do to minimize the effect of this switch time: Use the OTP direction to minimize how long it takes, and choose a break point where a freeze is not as noticeable. Alternatively, you can choose to use a seamless layer change.

Choosing Seamless or Non-Seamless Layer Changes

DVD Studio Pro includes a setting that allows you to choose between a seamless layer change or a non-seamless layer change.

With the seamless layer change, the switch between the first and second layer is less detectable. With the non-seamless layer change, there is a short pause when the DVD player switches between the layers.

While the seamless layer change would appear to be the best choice, some DVD players do not support the seamless feature, and may stop playing the disc once the switch point is reached. For that reason, it is strongly suggested that you use the default non-seamless layer change setting.

To change the layer change setting
  1. Click the Disc/Volume tab in the Disc Inspector.

  2. Do one of the following:

    • To use the normal layer change setting: Leave the Seamless checkbox deselected.
    • To force a non-standard seamless layer change setting: Select the Seamless checkbox.

Setting the Dual-Layer Direction

The disc’s first layer always starts on the inside edge, near the disc’s spindle hole. The disc plays from this point toward the outer edge.

It is the second layer’s direction that you have to choose. With the Parallel Track Path (PTP) setting, the second layer is configured exactly like the first layer—it begins on the inside and plays toward the outside. With the Opposite Track Path (OTP) setting, the second layer begins on the outside edge and plays toward the inside.

Note: Double-layer discs require you to use the OTP setting.

With the PTP setting, the DVD player will need more time when switching between layers because the laser must be repositioned from one end of the disc to the other. Using the OTP setting minimizes the time needed to reposition the laser because the end of the first layer is near the beginning of the second layer.

Important: When using the OTP setting, the first layer must be larger than the second layer.

About Choosing a Dual-Layer Break Point

Several factors need to be taken into account when you choose where to place the dual-layer break point:

  • Break points must be on track markers: When you choose the break point, you get a list of track markers to choose from. In some circumstances, you may need to place a marker on a track just for this purpose. See Setting the Dual-Layer Break Point for more information.

    Note: In some special cases, you can set your dual-layer break point in the DVD-ROM area. See Setting the Break Point with Large DVD-ROM Contents for more information.

  • Break points need to be placed so that the first layer is mostly filled: A red laser dual-layer disc can hold 7.95 binary gigabytes and a blue laser dual-layer disc can hold 27.94 binary gigabytes. (See Making Sure Your Content Will Fit for information on disc sizes and DVDs.) Each red laser disc layer can hold approximately 3.9 binary gigabytes, and each blue laser disc layer can hold approximately 13.9 binary gigabytes. The closer your project comes to filling the disc, the more critical it is that you get as much content as possible on the first layer, and place the break point accordingly. Additionally, using the OTP direction setting requires the first layer to be larger than the second layer. See Manually Determining the Break Point Position for information on determining at which track the first layer will be filled.
  • Break points are best when they are not noticed: A layer switch that occurs during a tense action-packed scene can disrupt the viewer’s attention. When possible, it is best to place the break point in a scene with little action, or even better, at a scene transition, such as a fade to black.

Setting the Break Point with Large DVD-ROM Contents

Authoring a project that contains a small amount of DVD-Video data with a large amount of DVD-ROM data requires special handling for placing the break point. For example, you might author a project for a dual-layer red laser disc that contains 2 GB of DVD-Video data and 6 GB of DVD-ROM data. In this case, you will not be able to set a break point at a track’s marker because the DVD-ROM data will not fit on a single layer.

In these cases, setting the break point to Automatic places the break point in the DVD-ROM data.

Setting the Dual-Layer Break Point

There are several methods you can use to set a dual-layer break point:

  • The automatic method: By default, once you configure the disc as dual-layer, Automatic is selected as the break point in the Disc/Volume tab in the Disc Inspector. With this setting, DVD Studio Pro chooses the last marker that fits in the first layer. In cases where there is a large amount of ROM data, the automatic method can also place the break point in the ROM data. See Setting the Break Point with Large DVD-ROM Contents for more information.

    If you are using the Build/Format command, the automatic method has the greatest chance of success, because it will be able to choose the break point marker once the build process is finished without having to pause for you to choose the marker to use.

    It is possible that your project does not have a suitable marker for use as the dual-layer break point. In that case, the format is canceled and you must add a suitable marker to a track in your project. (Another option might be to rearrange the order of the tracks in the VTS Editor. See Moving Elements from One VTS to Another for more information.) See Manually Determining the Break Point Position.

  • Assign a break point marker in the Track Editor: This method allows you to choose the marker to use as the break point while working with your tracks. The disadvantage of this method is that, until you build your project, it can be difficult to choose a suitable marker as the break point. This is especially true if your project has a lot of transitions or you are using assets that have not yet been MPEG-2 encoded.

    If you choose an inappropriate marker, the format process will automatically cancel, with a dialog advising you of the problem it encountered.

  • Choose the break point marker when you start the format process: After you have built your project, the Dual-Layer Break Point pop-up menu in the Disc/Volume tab in the format dialog shows all suitable markers that you can choose from, with those that are inappropriate dimmed. This option has the advantage of letting you choose the marker to use from a list of known suitable markers. The disadvantage is that you have to build your project first.

    As with the automatic method, it is possible that there are no suitable markers, with no markers appearing in the pop-up menu. This means that you will have to add a suitable marker to a track in your project, or try rearranging the tracks in the VTS Editor. See Manually Determining the Break Point Position.

Manually Determining the Break Point Position

You can usually determine which track will be playing at the point where the break point is set by looking at the contents of the VIDEO_TS or HVDVD_TS folder. DVD Studio Pro writes the tracks to disc in their order in the Outline tab’s By VTS display. For SD projects, the first track listed becomes VTS_01_1.VOB, VTS_01_2.VOB, VTS_01_3.VOB, and so on (depending on the size of the track’s assets, with each VOB file being a maximum of 1 GB). The second track becomes VTS_02_1.VOB, and so on.

For HD projects, the first track listed becomes HV001T01.EVO, HV001T02.EVO, and so on, with each EVO file being a maximum of 1 GB. The second track becomes HV002T01.EVO.

See Standard SD DVD Video Zone Files and Standard HD DVD Video Zone Files for more information on identifying the files and on determining which files contain the menus, which will allow you to take them into account.

For example, when authoring for a red laser disc, by adding the file sizes together, starting with VTS_01, you can determine at which track the first layer’s 3.9 GB limit will be reached, and even get a rough idea of where in that track this will happen. You may decide to reorder the tracks with the VTS Editor to ensure the break happens in a noncrucial track.