Delay: Video

Functionality

The Video Delay block delays the audio from input to output by a time calculated from a video frame rate and a number of frames. Some video processors delay video by a fixed number of frames. Delaying the audio by an equal time avoids a lip-sync effect during playback. The Video Delay block takes Frame Rate and Frames parameters, calculates the delay required to equal the video delay through a video processor, and then applies that delay to all channels in the Video Delay block. The delay time is adjustable from 0 seconds to the maximum delay setting, in 21 microsecond increments. The maximum delay available to the block is 250 milliseconds to 500 milliseconds (12 frames at 24 frames per second), adjustable in 21 microsecond increments. Adjusting the maximum delay recompiles the HAL DSP code, which forces the software to disconnect if connected to a HAL device.

How to Use

The Video Delay block is most useful for aligning video and audio streams.

Adding the Block to Your System

Click the Processing tab to open the Processing Workspace.
In the palette area, click the DSP tab.
Expand the Misc: level, delay, meter... category of blocks.
Click and drag the Delay: Video block into your Processing Map.
Wire it into your system in the appropriate location. If you need additional inputs and outputs, simply wire to the <Add> node or click the <Add> text. Each input channel is routed to the opposing output channel through a delay.
(Optional) Customize the names of the block and/or the input and output channels by clicking their current name and then typing the custom name in the text box that appears. Click the X to save the name.

Configuring the Block

Open the Level block's properties by double-clicking the block or hovering and clicking the properties icon that appears in the upper right of the block's title bar. The properties dialog box contains Frame Rate and Frames controls. Designers typically use the Video Delay block to delay audio by the same number of frames that a video processor delays the video. From this dialog box, you can do the following:

Select the appropriate Frame Rate from the drop-down list. This value should represent the frame rate of your video processor.
Set the Frames value, which should represent the number of frames that your video processor is delaying the video stream.

note: Halogen automatically calculates the required delay to align the video and audio channels.

Adjust the Max Delay setting. To do so, expand the Max Delay area and adjust its value using the slider or by entering a value in the Max Delay edit box. You can increase the value from its default of 250 milliseconds to a maximum of 500 milliseconds.
note: Adjusting the Max Delay value reallocates DSP memory, which requires a recompile of the HAL DSP code. If Halogen is connected to a HAL device, Halogen disables the Max Delay control to prevent DSP recompile.
tip: When you store the Video Delay block in a preset, Halogen does not store the Max Delay parameter (to prevent the preset from changing the Max Delay value, resulting in a recompile of the HAL DSP code). Set the Max Delay value so that all required block delay settings are available using the Frame Rate and Frames controls. You can then use the Frame Rate and Frames controls to achieve different delays by storing the Video Delay block in presets that recall different Frame Rate and Frames settings.

User Interface Elements

Delay: Video Block

UI Element	Purpose
Input node	Connection point for wiring input to the Video Delay block. Each input channel is routed to the opposing output channel through a level control.
Output node	Connection point for wiring the Video Delay input channel to a specific output
<Add> nodes	Click to add another Input/Output pair of nodes, or wire to the <Add> node to automatically create a new channel.

Delay: Video Block Properties

(Hover over the thumbnail below to view the properties dialog box.)

When not connected to HAL: (Offline)

When connected to HAL: (Online)


UI Element	Purpose
Frame Rate	Represents the frame rate of your video processor. Select the appropriate option from the dropdown list. The Video Delay block uses this value in addition to the Frames value to calculate the required delay to equal the video delay through a video processor, and then applies this delay to all the block’s channels. Default = 23.976 fps (NTSC)
Frames	Represents the number of frames that your video processor is delaying the video stream. Select the appropriate number by clicking on the slider or entering a value in the edit box. Range is 0 to 12. The Video Delay block uses this value in addition to the Frame Rate value to calculate the required delay to equal the video delay through a video processor, and then applies this delay to all the block’s channels. Default = 0
Max Delay	Specifies the maximum allowable delay. Changing this value causes the DSP code to recompile. If Halogen is connected to a HAL device, the Max Delay control is disabled and displays a warning icon and note indicating that the control is for offline use only. Because of this recompile requirement, Halogen does not save this parameter to presets (when you add this block to a preset). Ranges from 250 to 500 milliseconds, adjustable in 21 microsecond increments. Default = 500 milliseconds