Chapter 3. Setting Up Audio Synchronization

This chapter shows you how to synchronize audio with video when you use the DM3 board in a typical studio configuration with a tape deck.

The following topics are covered:

Synchronizing Audio

To synchronize audio on an SGI Onyx 350 graphics system or a Silicon Graphics Tezro visual workstation (rackmountable and deskside), you need to install an SGI PCI digital audio board in your system.


Note: For instructions on installing the SGI PCI digital audio board, see your system user's guide.



Warning: To prevent serious physical damage to the Onyx 350 graphics system and the Silicon Graphics Tezro visual workstation (rackmountable and deskside), you must use the latest revision of the PCI digital audio board (PN 030-1649-001 or later).

To synchronize audio on an SGI Onyx 350 graphics system and a Silicon Graphics Tezro visual workstation (rackmountable and deskside), follow these steps:

  1. Connect a house sync generator to a digital tape deck, as shown in Figure 3-1.

  2. Connect the breakout cable that is included with the PCI digital audio board to the DB15 connector on the board.

  3. Connect the AES 1/2 output on the digital tape deck to the PCI digital audio board breakout cable's AES input connector (red wire).


    Note: For additional functionality, you can purchase a second PCI digital audio board for your system.


If you have a second PCI digital audio board installed, proceed as follows:

  1. Connect the provided breakout cable to the DB15 connector on the second board.

  2. Connect the AES 3/4 output on the digital tape deck to the breakout cable's AES input connector (red wire) on the second board (see Figure 3-1).

    For more information on the PCI digital audio board and breakout cable, see the PCI Digital Audio Board Installation Guide.

    Figure 3-1. Synchronizing Audio

    Synchronizing Audio

Setting Up Audio Panel

For the configuration shown in Figure 3-1, you can use the Audio Panel to perform the following functions:

  • Display the AES device controls

  • Set the default input and output to AES I/O

  • Set the audio signal path to AES I/O

  • Set the output sync source

Displaying AES Device Controls

To display the AES device controls, follow these steps:

  1. Open the Audio Panel by selecting Desktop > Control Audio from the Toolchest.

  2. Select the desired AES device control panel from the View menu.

    The selected device control panel appears, where you can adjust parameters such as sample rate, input source, and output destination. For details, refer to the Audio Panel Help menu.

Setting Default Input and Output to AES

The Audio Panel window displays device controls for ADAT In, ADAT Out, AES In, and AES Out for each PCI digital audio board installed in your system. You can designate any of these devices as a default, which means your system uses the device as the internal audio device unless otherwise specified by another application. To set the default input and output, simply open the Audio Panel and select a default input and output device in the Default menu.

Setting Input and Output Signal Path

You can select either electrical or optical signal paths for the AES input and output devices. To set the input source with the Audio Panel, follow these steps:

  1. Position the cursor over the input device panel (if the device panel you need is not displayed, use the View menu), then hold down the right mouse button to display the menu for the desired input device.

  2. Select Preferences from the input device menu.

    The Preferences menu appears for the respective input device.

  3. Choose the input source (for example, AES In) that you want the input device to use. “AES In” is the electrical input.

To set the output destination with the Audio Panel, follow these steps:

  1. Position the cursor over the output device panel (if the device panel you need is not displayed, use the View menu), then hold down the right mouse button to display the menu for the desired output device.

  2. Select Preferences from the output device menu, as shown in Figure 3-2.

    The Preferences menu appears for the respective output device, as shown in Figure 3-3.

  3. Choose the output destination (for example, “AES Out”) that you want the output device to use. “AES Out” is the coaxial digital electrical output.

    Selecting the optical input or output for AES disables the ADAT input or output, because the two devices share the same optical connector. Similarly, selecting the optical input or output for ADAT automatically switches the AES input or output to the coaxial digital electrical connector.

    If more than one PCI digital audio board is installed, the system names each board using an incremental prefix naming scheme. For this type of configuration, one AES input is displayed as “RAD 1.AES In” and the other as “RAD 2.AES In.” Also, one AES output is displayed as “RAD 1.AES Out” and the other as “RAD 2.AES Out (see Figure 3-2).

Setting Output Sync Source

To set the output sync source, follow these steps:

  1. Position the cursor over the output device panel (if the device panel you need is not displayed, use the View menu), then hold down the right mouse button to display the menu for the desired output device.

  2. Select Preferences from the output device menu, as shown in Figure 3-2.

    The Preferences menu appears for the respective output device, as shown in Figure 3-3.

    Figure 3-2. Selecting Preferences for Output Device

    Selecting 
Preferences for Output Device

  3. Choose the sync source that you want the output device to use.

The example in Figure 3-3 shows how to select a sync source for a system that contains one PCI digital audio board.

Figure 3-3. Synchronizing One PCI Digital Audio Board

Synchronizing One PCI Digital Audio Board

Figure 3-4 and Figure 3-5 show how to select a sync source for a system that contains two PCI digital audio boards. Figure 3-4 shows the selection using the RAD 1.AES Out Preferences window, which contains the preferences for the first PCI digital audio board.

Figure 3-4. Synchronizing Two PCI Digital Audio Boards (RAD 1.AES Out Preferences)

Synchronizing Two PCI Digital Audio Boards (RAD 1.AES Out Preferences)

Figure 3-5 shows the selection using the RAD 2.AES Out Preferences window, which contains the preferences for the second PCI digital audio board.

Figure 3-5. Synchronizing Two PCI Digital Audio Boards (RAD 2.AES Out Preferences)

Synchronizing Two PCI Digital Audio Boards (RAD 2.AES Out Preferences)

Other Configurations

The DM3 board does not support audio synchronization using Internal Video as a sync source in the Audio Panel AES or ADAT Out Preferences, or the Analog In/Out Preferences.

In addition to the examples described earlier in this chapter, there are other optional configurations. For example, you can synchronize the PCI digital audio board's audio input to a house sync generator as follows:

  1. Connect the house sync generator to one of the breakout cable's video reference loop connectors (green or black wires).

    If you are not using the other video reference loop connector to loop the video reference signal through another device, place a 75-ohm terminator on the unused connector.

  2. From the Audio Panel, hold down the right mouse button to display the menu for the desired output device.

  3. Select Preferences in the output device menu.

  4. Select Video as the sync source.


    Note: To synchronize a digital audio (AES or ADAT) input to a video reference, the input must be synchronized externally because it is externally sampled. The examples described earlier in this chapter (using a tape deck) reflect this requirement.