2.4.13 Synchronized Capture/Playback

Multiple DeckLink devices or sub-devices can be grouped to synchronously start and stop capture or playback.

2.4.13.1 Synchronized Capture

All sources providing the signal to the capture devices must have their clocks synchronized. This can be achieved by providing the sources with a common reference input. However it is not required that the reference input is proved to the DeckLink capture devices. All sources should be configured with the same frame rate.

An application performing synchronized capture should perform the following steps:

For each device to synchronize for capture:

• Call IDeckLinkProfileAttributes::GetFlag() with the BMDDeckLinkSupportsSynchronizeToCaptureGroup flag to check that the DeckLink hardware supports grouping for synchronized capture.

• Call IDeckLinkConfiguration::SetInt() with the bmdDeckLinkConfigCaptureGroup configuration ID, along with a common integer value for the capture group. This setting is persistent until system reboot.

• Obtain an IDeckLinkInput interface object by calling IUnknown::QueryInterface() on the IDeckLink object with IID_IDeckLinkInput.

• Enable each input in the capture group by calling IDeckLinkInput::EnableVideoInput(), with the bmdVideoInputSynchronizeToCaptureGroup flag.

• IDeckLinkInput::EnableAudioInput()

• IDeckLinkInput::SetCallback()

• Call IDeckLinkStatus::GetFlag() with the bmdDeckLinkStatusVideoInputSignalLocked status ID to ensure that the input is locked.

• To start the synchronized capture call IDeckLinkInput::StartStreams() on any input device in the group.

• To stop synchronized capture, call IDeckLinkInput::StopStreams() on any input device in the group.

2.4.13.2 Synchronized Playback

Each output device in the synchronized playback group requires a common reference. The exception is the DeckLink 8K Pro, where all sub-devices can synchronize to each other without needing a common reference input. All output devices should be configured with the same frame rate.

An application performing synchronized playback should perform the following steps

For each device to synchronize for playback:

• Call IDeckLinkProfileAttributes::GetFlag() with the BMDDeckLinkSupportsSynchronizeToPlaybackGroup flag to check that the DeckLink hardware supports grouping for synchronized playback.

• Call IDeckLinkConfiguration::SetInt() with the bmdDeckLinkConfigPlaybackGroup configuration ID, along with a common integer value for the playback group. This setting is persistent until system reboot.

• Obtain an IDeckLinkOutput interface object by calling IUnknown::QueryInterface() on the IDeckLink object with IID_IDeckLinkOutput.

• IDeckLinkOutput::DoesSupportVideoMode() to check if the combination of the video mode and pixel format is supported.

• Enable each output in the playback group by calling IDeckLinkOutput::EnableVideoOutput(), with the bmdVideoOutputSynchronizeToPlaybackGroup flag.

• IDeckLinkOutput::EnableAudioOutput()

• IDeckLinkOutput::SetScheduledFrameCompletionCallback()

• IDeckLinkOutput::SetAudioCallback()

• IDeckLinkOutput::BeginAudioPreroll()

• If a common reference is required, for each output in the playback group, call IDeckLinkStatus::GetFlag() with the bmdDeckLinkStatusReferenceSignalLocked status ID to ensure that the output is locked to the reference input.

• To start the synchronized playback call IDeckLinkOutput::StartScheduledPlayback() on any output in the group.

• To stop synchronized playback, call IDeckLinkOutput::StopScheduledPlayback() on any output in the group.