HD-SDI Output in Silverstack

Silverstack XT and Silverstack Lab come with HD-SDI output to play out ingested clips in best quality for QC on an HD-SDI broadcast monitor. The current clip in the player gets mirrored to the HD-SDI output showing the image in full-screen and 10 bit color depth.

Supported Devices

To enable the HD-SDI output you need one of the following devices:

  • AJA T-TAP
  • AJA KONA series
  • AJA Io series
  • Blackmagic Design Ultrastudio Products
  • Blackmagic Design Mini Monitor
  • Blackmagic Design Decklink Cards

Attach the according interface to your Mac (Thunderbolt or PCIe) and connect the HD-SDI output of the device to the selected destination.

Figure 1: Schematic presentation of a Silverstack HD-SDI setup

Figure 1: Schematic presentation of a Silverstack XT HD-SDI setup

Drivers

In order to use the supported devices you have to install all drivers and necessary software provided by the the manufacturer.

For Blackmagic Design devices that is the “Desktop Video” software you can download in their support area.

For AJA Devices that are the “AJA hardware drivers” included in the latest “AJA software installers” also available in their support area.

External Video Preferences

As soon as the HD-SDI device is connected, Silverstack XT  requests permission to use it for playback. In case you decide to activate the SDI playback later, you can enable it through “Preferences>External Video”. You can disable the use of the device from the same menu in case another application demands its use (i.e. parallel use of the hardware with other software). If you have multiple output devices attached, you can select which one to use by choosing it in the drop down menu:

Figure 2: External Video settings

Figure 2: External Video settings

For the “Video Format” you will be able to choose from two settings:

  • Try to Match Clip: This setting will try to match the output format of the SDI to the settings of the clips. Silverstack will try to keep the frame rate and fall back to HD if the resolution is not supported. If the frame rate is not supported it will fall back to 1080p25.  In detail this means:
    • Frame rate supported / resolution not supported: Silverstack will keep the frame rate. The resolution will fall back to a 1920 x 1080 (HD).
    • Frame rate not supported / resolution supported:  Silverstack will fall back to 1080p25.
  • Fixed : This setting will let you choose the output format manually.

Additionally you can choose to release the device when Silverstack XT is in background by enabling the checkbox “Release device when Silverstack is in background”. By default it will be kept even if Silverstack XT is in background.

Please be aware that the support of SDI formats depends on the compatibility of the attached hardware device that the implementation in Silverstack bases on.

The HD-SDI Indicator

As soon as you enable the external video output in the preferences a little indicator in the toolbar of the Silverstack XT media player will give you hints on the status of the HD-SDI output:

Figure3: The HD-SDI indicator will show up in the toolbar of the media player and the <a href="#miniplayer">Miniplayer</a>.

Figure 3: The HD-SDI indicator will show up in the toolbar of the media player and the Miniplayer.

There are 3 statuses possible:

1. HD-SDI output enabled and working:

Figure 4: HD-SDI Indicator showing a working HD-SDI output.

Figure 4: HD-SDI Indicator showing a working HD-SDI output.

Click on the indicator to reach the External video out settings with the settings for the HD-SDI output.

2. HD-SDI output enabled but no device attached:

Figure 5: HD-SDI indicator showing that no device is attached

Figure 5: HD-SDI indicator showing that no device is attached

Click on the indicator to reach the External video preferences to set up your attached device.

3. HD-SDI output has problems

Figure 6: HD-SDI indicator notifying about problems with the attached device

Figure 6: HD-SDI indicator notifying about problems with the attached device

Click on the indicator to see details about the problem.

A usual case causing this status of the indicator would be another application that tries to use the same HD-SDI device as Silverstack XT. Deactivate the background use in the preferences of the application trying to use the same devices as Silverstack XT to avoid the problem.

Playback Modes

You can choose between two playback modes:

  • Absolute Time Playback: Tries to play back footage in sync with audio. Silverstack XT will skip frames to stay in sync with audio when video processing or I/O is too slow.
  • Every Frame Playback: Aims to play back frame exact which leads to loosing audio. Silverstack XT will play back frame exact even if that leads to non-realtime playback.

To select the desired mode go to “Playback” in the main menu of LiveGrade and select the according entry right at the top:

figure 3: Select playback mode from the main menu

figure 7: Select playback mode from the main menu

Image processing

There are different options when it comes to display the clips through the SDI device. You can modify these settings on the External Video Out window.

figure 4:

figure 8: External Video Out settings window

These are the available settings:

  • Visual Controls: enable/disable the «Image Analyses» like False Color and Exposure Range, as well as Framelines. Learn more about frame lines from the article Frame Lines in the Playback View.
  • Scaling and Position:
    • Scale to fit: fills the output display with the image to compensate for a difference in the resolution.
    • 1:1 Pixels: displays the image in full resolution, which can crop the image id the output display has less resolution than the source.

 

Supported Frame Rates and Resolutions

Supported frame rates and resolutions are:

  • 720p50
  • 720p59.98
  • 1080p23.98
  • 1080p24
  • 1080p25
  • 1080p29.97
  • 1080p30

Silverstack XT has a fallback resolution (1920 x 1080 HD) and frame rate (25p) that is executed when the desired resolution and frame rate is not supported by your hardware device. That means if either frame rate or resolution is not a native SDI format the SDI output will fall back to 1080p25.

Interlaced formats are currently not supported.

HD-SDI Features and Quality Characteristics

Color Reproduction HD video matrix and gamma (ITU-R BT.709; ITU-R BT.1886)
Timing Sync to next available video frame rates (see Supported Frame Rates and Resolutions and Playback Modes)
Code Values 10-bit legal range YCbCr output (internal 16-bit RGB processing)
Embedded Audio Not supported
Metadata Output Not supported

The Miniplayer

Additionally, you can enable the Miniplayer from the same menu, which enables to monitor the same image sent through the SDI output on the computer display, at the same time as you navigate across the Project Library.

When the HD-SDI Output is enabled it will automatically open the Miniplayer to keep the HD-SDI output though you switched to the list or table view etc. As soon as you close the Miniplayer the HD-SDI output will be disabled.

You can reopen the Miniplayer manually from the Main Menu. Go to “Playback > Show Miniplayer” to open it up again. You can also open it from the Miniplayer symbol in the header bar on the right.

figure 4: the Miniplayer

figure 9: the Miniplayer