# Blackmagic Decklink Integration with Media Blocks SDK

Media Blocks SDK .Net

The VisioForge Media Blocks SDK for .NET provides robust support for Blackmagic Decklink devices, enabling developers to implement professional-grade audio and video functionality in their applications. This integration allows for seamless capture and rendering operations using Decklink's high-quality hardware.

Our SDK includes specialized blocks designed specifically for Decklink devices, giving you full access to their capabilities including SDI, HDMI, and other inputs/outputs. These blocks are optimized for performance and offer a straightforward API for implementing complex media workflows.

• Audio Capture and Rendering: Capture and output audio through Decklink devices
• Video Capture and Rendering: Capture and output video in various formats and resolutions
• Multiple Device Support: Work with multiple Decklink devices simultaneously
• Professional I/O Options: Utilize SDI, HDMI, and other professional interfaces
• High-Quality Processing: Maintain professional video/audio quality throughout the pipeline
• Combined Audio/Video Blocks: Simplified handling of synchronized audio and video streams with dedicated source and sink blocks.

Before using the Decklink blocks, ensure your system meets these requirements:

• Hardware: Compatible Blackmagic Decklink device
• Software: Blackmagic Decklink SDK or drivers installed

The SDK provides several block types for working with Decklink devices:

1. Audio Sink Block: For audio output to Decklink devices.
2. Audio Source Block: For audio capture from Decklink devices.
3. Video Sink Block: For video output to Decklink devices.
4. Video Source Block: For video capture from Decklink devices.
5. Video + Audio Sink Block: For synchronized video and audio output to Decklink devices using a single block.
6. Video + Audio Source Block: For synchronized video and audio capture from Decklink devices using a single block.

Each block type is designed to handle specific media operations while maintaining synchronization and quality.

The Decklink Audio Sink block enables audio output to Blackmagic Decklink devices. This block handles the complexities of audio timing and device interfacing.

Before creating an audio sink block, you'll need to enumerate available devices:

var devices = await DecklinkAudioSinkBlock.GetDevicesAsync();
foreach (var item in devices)
{
    Console.WriteLine($"Found device: {item.Name}, Device Number: {item.DeviceNumber}");
}

This code retrieves all available Decklink devices that support audio output functionality.

Once you've identified the target device, you can create and configure the audio sink block:

// Get the first available device
var deviceInfo = (await DecklinkAudioSinkBlock.GetDevicesAsync()).FirstOrDefault();

// Create settings for the selected device
DecklinkAudioSinkSettings audioSinkSettings = null;
if (deviceInfo != null)
{
    audioSinkSettings = new DecklinkAudioSinkSettings(deviceInfo);
    // Example: audioSinkSettings.DeviceNumber = deviceInfo.DeviceNumber; (already set by constructor)
    // Further configuration:
    // audioSinkSettings.BufferTime = TimeSpan.FromMilliseconds(100);
    // audioSinkSettings.IsSync = true;
}

// Create the block with configured settings
var decklinkAudioSink = new DecklinkAudioSinkBlock(audioSinkSettings);

The DecklinkAudioSinkSettings class includes properties like:

• DeviceNumber: The output device instance to use.
• BufferTime: Minimum latency reported by the sink (default: 50ms).
• AlignmentThreshold: Timestamp alignment threshold (default: 40ms).
• DiscontWait: Time to wait before creating a discontinuity (default: 1s).
• IsSync: Enables synchronization (default: true).

The audio sink block includes an Input pad that accepts audio data from other blocks in your pipeline:

// Example: Connect an audio source/encoder to the Decklink audio sink
audioEncoder.Output.Connect(decklinkAudioSink.Input);

The Decklink Audio Source block enables capturing audio from Blackmagic Decklink devices. It supports various audio formats and configurations.

Enumerate available audio source devices:

var devices = await DecklinkAudioSourceBlock.GetDevicesAsync();
foreach (var item in devices)
{
    Console.WriteLine($"Available audio source: {item.Name}, Device Number: {item.DeviceNumber}");
}

Create and configure the audio source block:

// Get the first available device
var deviceInfo = (await DecklinkAudioSourceBlock.GetDevicesAsync()).FirstOrDefault();

// Create settings for the selected device
DecklinkAudioSourceSettings audioSourceSettings = null;
if (deviceInfo != null)
{
    // create settings object
    audioSourceSettings = new DecklinkAudioSourceSettings(deviceInfo);
    // Further configuration:
    // audioSourceSettings.Channels = DecklinkAudioChannels.Ch2;
    // audioSourceSettings.Connection = DecklinkAudioConnection.Embedded;
    // audioSourceSettings.Format = DecklinkAudioFormat.S16LE; // SampleRate is fixed at 48000
}

// Create the block with the configured settings
var audioSource = new DecklinkAudioSourceBlock(audioSourceSettings);

The DecklinkAudioSourceSettings class includes properties like:

• DeviceNumber: The input device instance to use.
• Channels: Audio channels to capture (e.g., DecklinkAudioChannels.Ch2, Ch8, Ch16). Default Ch2.
• Format: Audio sample format (e.g., DecklinkAudioFormat.S16LE). Default S16LE. Sample rate is fixed at 48000 Hz.
• Connection: Audio connection type (e.g., DecklinkAudioConnection.Embedded, AES, Analog). Default Auto.
• BufferSize: Internal buffer size in frames (default: 5).
• DisableAudioConversion: Set to true to disable internal audio conversion. Default false.

The audio source block provides an Output pad that can connect to other blocks:

// Example: Connect the audio source to an audio encoder or processor
audioSource.Output.Connect(audioProcessor.Input);

The Decklink Video Sink block enables video output to Blackmagic Decklink devices, supporting various video formats and resolutions.

Find available video sink devices:

var devices = await DecklinkVideoSinkBlock.GetDevicesAsync();
foreach (var item in devices)
{
    Console.WriteLine($"Available video output device: {item.Name}, Device Number: {item.DeviceNumber}");
}

Create and configure the video sink block:

// Get the first available device
var deviceInfo = (await DecklinkVideoSinkBlock.GetDevicesAsync()).FirstOrDefault();

// Create settings for the selected device
DecklinkVideoSinkSettings videoSinkSettings = null;
if (deviceInfo != null)
{
    videoSinkSettings = new DecklinkVideoSinkSettings(deviceInfo);
    
    // Configure video output format and mode
    videoSinkSettings.Mode = DecklinkMode.HD1080i60;
    videoSinkSettings.VideoFormat = DecklinkVideoFormat.YUV_10bit; // Use VideoFormat
    
    // Optional: Additional configuration
    // videoSinkSettings.KeyerMode = DecklinkKeyerMode.Internal;
    // videoSinkSettings.KeyerLevel = 128;
    // videoSinkSettings.Profile = DecklinkProfileID.Default;
    // videoSinkSettings.TimecodeFormat = DecklinkTimecodeFormat.RP188Any;
}

// Create the block with the configured settings
var decklinkVideoSink = new DecklinkVideoSinkBlock(videoSinkSettings);

The DecklinkVideoSinkSettings class includes properties like:

• DeviceNumber: The output device instance to use.
• Mode: Specifies the video resolution and frame rate (e.g., DecklinkMode.HD1080i60, HD720p60). Default Unknown.
• VideoFormat: Defines the pixel format using DecklinkVideoFormat enum (e.g., DecklinkVideoFormat.YUV_8bit, YUV_10bit). Default YUV_8bit.
• KeyerMode: Controls keying/compositing options using DecklinkKeyerMode (if supported by the device). Default Off.
• KeyerLevel: Sets the keyer level (0-255). Default 255.
• Profile: Specifies the Decklink profile to use with DecklinkProfileID.
• TimecodeFormat: Specifies the timecode format for playback using DecklinkTimecodeFormat. Default RP188Any.
• IsSync: Enables synchronization (default: true).

The Decklink Video Source block allows capturing video from Blackmagic Decklink devices, supporting various input formats and resolutions.

Enumerate video capture devices:

var devices = await DecklinkVideoSourceBlock.GetDevicesAsync();
foreach (var item in devices)
{
    Console.WriteLine($"Available video capture device: {item.Name}, Device Number: {item.DeviceNumber}");
}

Create and configure the video source block:

// Get the first available device
var deviceInfo = (await DecklinkVideoSourceBlock.GetDevicesAsync()).FirstOrDefault();

// Create settings for the selected device
DecklinkVideoSourceSettings videoSourceSettings = null;
if (deviceInfo != null)
{
    videoSourceSettings = new DecklinkVideoSourceSettings(deviceInfo);
    
    // Configure video input format and mode
    videoSourceSettings.Mode = DecklinkMode.HD1080i60;
    videoSourceSettings.Connection = DecklinkConnection.SDI; 
    // videoSourceSettings.VideoFormat = DecklinkVideoFormat.Auto; // Often used with Mode=Auto
}

// Create the block with configured settings
var videoSourceBlock = new DecklinkVideoSourceBlock(videoSourceSettings);

The DecklinkVideoSourceSettings class includes properties like:

• DeviceNumber: The input device instance to use.
• Mode: Specifies the expected input resolution and frame rate (e.g., DecklinkMode.HD1080i60). Default Unknown.
• Connection: Defines which physical input to use, using DecklinkConnection enum (e.g., DecklinkConnection.HDMI, DecklinkConnection.SDI). Default Auto.
• VideoFormat: Specifies the video format type for input, using DecklinkVideoFormat enum. Default Auto (especially when Mode is Auto).
• Profile: Specifies the Decklink profile using DecklinkProfileID. Default Default.
• DropNoSignalFrames: If true, drops frames marked as having no input signal. Default false.
• OutputAFDBar: If true, extracts and outputs AFD/Bar data as Meta. Default false.
• OutputCC: If true, extracts and outputs Closed Captions as Meta. Default false.
• TimecodeFormat: Specifies the timecode format using DecklinkTimecodeFormat. Default RP188Any.
• DisableVideoConversion: Set to true to disable internal video conversion. Default false.

The DecklinkVideoAudioSourceBlock simplifies capturing synchronized video and audio streams from a single Decklink device.

Device selection is managed through DecklinkVideoSourceSettings and DecklinkAudioSourceSettings. You would typically enumerate video devices using DecklinkVideoSourceBlock.GetDevicesAsync() and audio devices using DecklinkAudioSourceBlock.GetDevicesAsync(), then configure the respective settings objects for the chosen device. The DecklinkVideoAudioSourceBlock itself also provides GetDevicesAsync() which enumerates video sources.

// Enumerate video devices (for video part of the combined source)
var videoDeviceInfo = (await DecklinkVideoAudioSourceBlock.GetDevicesAsync()).FirstOrDefault(); // or DecklinkVideoSourceBlock.GetDevicesAsync()
var audioDeviceInfo = (await DecklinkAudioSourceBlock.GetDevicesAsync()).FirstOrDefault(d => d.DeviceNumber == videoDeviceInfo.DeviceNumber); // Example: match by device number

DecklinkVideoSourceSettings videoSettings = null;
if (videoDeviceInfo != null)
{
    videoSettings = new DecklinkVideoSourceSettings(videoDeviceInfo);
    videoSettings.Mode = DecklinkMode.HD1080i60;
    videoSettings.Connection = DecklinkConnection.SDI;
}

DecklinkAudioSourceSettings audioSettings = null;
if (audioDeviceInfo != null)
{
    audioSettings = new DecklinkAudioSourceSettings(audioDeviceInfo);
    audioSettings.Channels = DecklinkAudioChannels.Ch2;
}

// Create the block with configured settings
if (videoSettings != null && audioSettings != null)
{
    var decklinkVideoAudioSource = new DecklinkVideoAudioSourceBlock(videoSettings, audioSettings);

    // Connect outputs
    // decklinkVideoAudioSource.VideoOutput.Connect(videoProcessor.Input);
    // decklinkVideoAudioSource.AudioOutput.Connect(audioProcessor.Input);
}

You instantiate DecklinkVideoAudioSourceBlock by providing pre-configured DecklinkVideoSourceSettings and DecklinkAudioSourceSettings objects.

// Assuming videoSourceSettings and audioSourceSettings are configured as above
var videoAudioSource = new DecklinkVideoAudioSourceBlock(videoSourceSettings, audioSourceSettings);

The block provides separate VideoOutput and AudioOutput pads:

// Example: Connect to video and audio processors/encoders
videoAudioSource.VideoOutput.Connect(videoEncoder.Input);
videoAudioSource.AudioOutput.Connect(audioEncoder.Input);

The DecklinkVideoAudioSinkBlock simplifies sending synchronized video and audio streams to a single Decklink device.

Similar to the combined source, device selection is managed via DecklinkVideoSinkSettings and DecklinkAudioSinkSettings. Enumerate devices using DecklinkVideoSinkBlock.GetDevicesAsync() and DecklinkAudioSinkBlock.GetDevicesAsync().

var videoSinkDeviceInfo = (await DecklinkVideoSinkBlock.GetDevicesAsync()).FirstOrDefault();
var audioSinkDeviceInfo = (await DecklinkAudioSinkBlock.GetDevicesAsync()).FirstOrDefault(d => d.DeviceNumber == videoSinkDeviceInfo.DeviceNumber); // Example match

DecklinkVideoSinkSettings videoSinkSettings = null;
if (videoSinkDeviceInfo != null)
{
    videoSinkSettings = new DecklinkVideoSinkSettings(videoSinkDeviceInfo);
    videoSinkSettings.Mode = DecklinkMode.HD1080i60;
    videoSinkSettings.VideoFormat = DecklinkVideoFormat.YUV_8bit;
}

DecklinkAudioSinkSettings audioSinkSettings = null;
if (audioSinkDeviceInfo != null)
{
    audioSinkSettings = new DecklinkAudioSinkSettings(audioSinkDeviceInfo);
}

// Create the block
if (videoSinkSettings != null && audioSinkSettings != null)
{
    var decklinkVideoAudioSink = new DecklinkVideoAudioSinkBlock(videoSinkSettings, audioSinkSettings);
    
    // Connect inputs
    // videoEncoder.Output.Connect(decklinkVideoAudioSink.VideoInput);
    // audioEncoder.Output.Connect(decklinkVideoAudioSink.AudioInput);
}

Instantiate DecklinkVideoAudioSinkBlock with configured DecklinkVideoSinkSettings and DecklinkAudioSinkSettings.

// Assuming videoSinkSettings and audioSinkSettings are configured
var videoAudioSink = new DecklinkVideoAudioSinkBlock(videoSinkSettings, audioSinkSettings);

The block provides separate VideoInput and AudioInput pads:

// Example: Connect from video and audio encoders
videoEncoder.Output.Connect(videoAudioSink.VideoInput);
audioEncoder.Output.Connect(videoAudioSink.AudioInput);

Using separate source blocks:

// Assume videoSourceSettings and audioSourceSettings are configured for the same device/timing
var videoSource = new DecklinkVideoSourceBlock(videoSourceSettings);
var audioSource = new DecklinkAudioSourceBlock(audioSourceSettings);

// Create an MP4 encoder
var mp4Settings = new MP4SinkSettings("output.mp4");
var sink = new MP4SinkBlock(mp4Settings);

// Create video encoder
var videoEncoder = new H264EncoderBlock();

// Create audio encoder
var audioEncoder = new AACEncoderBlock();

// Connect video and audio sources
pipeline.Connect(videoSource.Output, videoEncoder.Input);
pipeline.Connect(audioSource.Output, audioEncoder.Input);

// Connect video encoder to sink
pipeline.Connect(videoEncoder.Output, sink.CreateNewInput(MediaBlockPadMediaType.Video));

// Connect audio encoder to sink
pipeline.Connect(audioEncoder.Output, sink.CreateNewInput(MediaBlockPadMediaType.Audio));

// Start the pipeline
await pipeline.StartAsync();

Using DecklinkVideoAudioSourceBlock for simplified synchronized capture: If you use DecklinkVideoAudioSourceBlock (as configured in its dedicated section), the source setup becomes:

// Assuming videoSourceSettings and audioSourceSettings are configured for the same device
var videoAudioSource = new DecklinkVideoAudioSourceBlock(videoSourceSettings, audioSourceSettings);

// ... (encoders and sink setup as above) ...

// Connect video and audio from the combined source
pipeline.Connect(videoAudioSource.VideoOutput, videoEncoder.Input);
pipeline.Connect(videoAudioSource.AudioOutput, audioEncoder.Input);

// ... (connect encoders to sink and start pipeline as above) ...

This ensures that audio and video are sourced from the Decklink device in a synchronized manner by the SDK.

• No Devices Found: Ensure Blackmagic drivers/SDK are installed and up-to-date. Check if the device is recognized by Blackmagic Desktop Video Setup.
• Format Mismatch: Verify the device supports your selected video/audio mode, format, and connection type. For sources with Mode = DecklinkMode.Unknown (auto-detect), ensure a stable signal is present.
• Performance Issues: Check system resources (CPU, RAM, disk I/O). Consider lowering resolution/framerate if issues persist.
• Signal Detection: For input devices, check cable connections and ensure the source device is outputting a valid signal.
• "Unable to build ...Block" errors: Double-check that all settings are valid for the selected device and mode. Ensure the correct DeviceNumber is used if multiple Decklink cards are present.

For complete working examples, refer to these sample applications:

• Decklink Demo

The Blackmagic Decklink blocks in the VisioForge Media Blocks SDK provide a powerful and flexible way to integrate professional video and audio hardware into your .NET applications. By leveraging the specific source and sink blocks, including the combined audio/video blocks, you can efficiently implement complex capture and playback workflows. Always refer to the specific settings classes for detailed configuration options.