Video Capture Configuration

Setup guide for the Blackmagic DeckLink Quad HDMI capture system in the Multi-Camera Livestream Framework.

Last Updated: Version: 1.0.0

Table of Contents

  1. Overview
  2. Hardware Setup
  3. DeckLink Configuration
  4. Camera Settings
  5. OBS Integration
  6. Resolution & Frame Rate
  7. Troubleshooting

Overview

The video capture pipeline uses a Blackmagic DeckLink Quad HDMI card in a Sonnet Echo Express SE I Thunderbolt 3 chassis, connected to the M1 Mac Studio.

Supported Inputs

Input Resolution Frame Rate Color Space
HDMI 1 Up to 4K Up to 60fps Various
HDMI 2 Up to 4K Up to 60fps Various
HDMI 3 Up to 4K Up to 60fps Various
HDMI 4 Up to 4K Up to 60fps Various

Note: When capturing 4K on multiple inputs simultaneously, bandwidth limitations may require using 4K30 or 1080p60.

Signal Flow

Cameras ──HDMI──→ DeckLink Quad HDMI ──PCIe──→ Echo Express ──TB3──→ Mac Studio ──→ OBS

Hardware Setup

Echo Express Chassis

  1. Position: Place chassis with adequate ventilation (generates heat)
  2. Power: Connect to UPS/power conditioner (powers on automatically)
  3. Thunderbolt: Connect to Mac Studio TB3 port
    • Use Port 1 for best bandwidth
    • Avoid daisy-chaining other devices

The DeckLink Quad HDMI should be pre-installed in the Echo Express chassis.

Verification:

system_profiler SPPCIDataType | grep -i decklink

HDMI Connections

Port Cable Type Max Length Notes
HDMI 1 HDMI 2.0+ 3m (10ft) for 4K
HDMI 2 HDMI 2.0+ 3m (10ft) for 4K
HDMI 3 HDMI 2.0+ 3m (10ft) for 4K
HDMI 4 HDMI 2.0+ 3m (10ft) for 4K

⚠️ For runs longer than 3m at 4K, use active HDMI cables or HDMI-over-fiber extenders.

Installing Drivers

  1. Download Desktop Video from Blackmagic Support
  2. Install the package (requires restart)
  3. Verify installation: 
    ls /Library/Application\ Support/Blackmagic\ Design/

Desktop Video Setup Utility

Launch Blackmagic Desktop Video Setup from Applications:

  1. Select each input
  2. Configure:
    • Video Input: HDMI
    • Video Format: Match your cameras (e.g., 1080p60)
    • Color Space: Rec.709 (default for most cameras)

Input Format Settings

Input Video Format Color Space Range
1 1080p60 Rec.709 Full
2 1080p60 Rec.709 Full
3 1080p60 Rec.709 Full
4 1080p60 Rec.709 Full

Camera Settings

For consistent multi-camera production:

Setting Value Notes
Resolution 1080p or 4K Match across all cameras
Frame Rate 60fps Or 30fps for all
White Balance Manual (5600K typical) Match all cameras
Exposure Manual or priority Consistent look
Color Profile Standard/Neutral Easier to match
HDMI Output Clean (no overlays) Critical!
HDMI Output Resolution Match capture format No scaling

Per-Camera Configuration

Camera 1: 

<!-- TODO: Add specific settings -->

Camera 2: 

<!-- TODO: Add specific settings -->

Camera 3: 

<!-- TODO: Add specific settings -->

Camera 4: 

<!-- TODO: Add specific settings -->

OBS Integration

  1. In OBS, click + in Sources
  2. Select Blackmagic Device
  3. Configure:
    • Device: DeckLink Quad HDMI (X) where X = input number
    • Mode: Match camera output format
    • Pixel Format: Auto (or match Desktop Video config)
    • Color Space: Rec.709
    • Color Range: Full (if cameras output full range)

OBS Source Naming Convention

Source Name DeckLink Input Camera
CAM1-Wide Input 1
CAM2-Host Input 2
CAM3-Guest Input 3
CAM4-Overhead Input 4

Scene Setup

Scene Collection: "Livestream-Main"
├── Scene: Full Screen
│   └── CAM1-Wide (full canvas)
├── Scene: Host Close-up
│   └── CAM2-Host (full canvas)
├── Scene: Split Screen
│   ├── CAM2-Host (left half)
│   └── CAM3-Guest (right half)
└── Scene: Picture-in-Picture
    ├── CAM1-Wide (full canvas)
    └── CAM2-Host (corner, scaled)

Resolution & Frame Rate

Bandwidth Considerations

The DeckLink Quad HDMI shares PCIe bandwidth across all inputs.

Configuration Total Bandwidth Notes
4x 1080p60 ~12 Gbps Recommended
2x 4K30 + 2x 1080p60 ~14 Gbps Workable
4x 4K30 ~18 Gbps May drop frames
4x 4K60 ~36 Gbps Not supported

For reliable 4-camera streaming:

  • All cameras: 1080p60
  • OBS Canvas: 1920x1080 @ 60fps
  • Stream Output: 1080p60 or 1080p30

4K Workflows

If you need 4K:

  1. Use 2 cameras at 4K30, 2 at 1080p60
  2. Or use 4K capture, downscale in OBS
  3. Monitor for dropped frames in OBS stats

Troubleshooting

No Signal Detected

Symptoms: OBS shows “No signal” for DeckLink source

Solutions:

  1. Check HDMI cable connection (both ends)
  2. Verify camera is outputting HDMI (check camera LCD)
  3. Confirm HDMI output is set to match capture format
  4. Check Desktop Video Setup for detected signal
  5. Power cycle the Echo Express chassis
  6. Try different HDMI port on DeckLink

Signal Flickering/Unstable

Symptoms: Image appears and disappears, or has artifacts

Solutions:

  1. Replace HDMI cable (cables degrade)
  2. Check for HDCP issues (disable on camera if possible)
  3. Ensure camera HDMI output matches DeckLink input format exactly
  4. Check for loose connections
  5. Try active HDMI cable for longer runs

Color/Exposure Mismatch Between Cameras

Symptoms: Cameras look different when switching

Solutions:

  1. Manual white balance on all cameras (same Kelvin value)
  2. Manual exposure (or same exposure compensation)
  3. Match color profiles/picture styles
  4. Use color correction in OBS if needed
  5. Consider video lighting for consistency

Dropped Frames

Symptoms: OBS shows “Frames missed due to rendering lag”

Solutions:

  1. Reduce capture resolution (4K → 1080p)
  2. Check Thunderbolt connection (avoid hubs)
  3. Close other GPU-intensive applications
  4. Update DeckLink drivers
  5. Monitor Mac GPU usage (Activity Monitor)

Symptoms: DeckLink doesn’t appear in OBS or Desktop Video Setup

Solutions:

  1. Restart Mac Studio
  2. Power cycle Echo Express chassis
  3. Check Thunderbolt cable connection
  4. Try different Thunderbolt port
  5. Reinstall Desktop Video drivers
  6. Check System Report → Thunderbolt for chassis detection

Audio Issues with HDMI Capture

Symptoms: Embedded HDMI audio not working or delayed

Solutions:

  1. We use Dante for audio—disable HDMI audio in OBS source
  2. If using HDMI audio, check Desktop Video audio settings
  3. Sync audio using OBS advanced audio properties

Quick Reference

Device: Blackmagic DeckLink Quad HDMI (1-4)
Mode: 1080p60 (or match camera)
Pixel Format: Auto
Color Space: Rec.709
Color Range: Full
Deactivate when not showing: Off (for faster switching)

Useful Commands

# Check DeckLink detection
system_profiler SPPCIDataType | grep -A10 -i "blackmagic"

# Check Thunderbolt devices
system_profiler SPThunderboltDataType

# List video input devices
system_profiler SPCameraDataType

See Also

Document maintained by Multi-Camera Livestream Framework team