Connectivity

SDI

SDI (Serial Digital Interface) is the professional broadcast standard for video transmission, using 75-ohm coaxial cable to carry uncompressed digital video over distances up to 100+ meters. Available in HD-SDI (1.5 Gbps), 3G-SDI (3 Gbps for 1080p60), and 12G-SDI (12 Gbps for 4K60), SDI provides the reliable, latency-free signal transport required for broadcast and live event production.

SDI: The Broadcast Video Standard

SDI (Serial Digital Interface) represents the professional video industry's standard for reliable, high-quality signal transmission. Understanding SDI is essential for broadcast, live event, and premium LED wall applications.

SDI Standards Evolution

| Standard | Bit Rate | Resolution/Frame Rate | Cable Length | |----------|----------|----------------------|--------------| | SD-SDI | 270 Mbps | 480i, 576i | 300m | | HD-SDI | 1.485 Gbps | 720p, 1080i | 100m | | 3G-SDI | 2.97 Gbps | 1080p60 | 100m | | 6G-SDI | 6 Gbps | 2160p30 | 50m | | 12G-SDI | 12 Gbps | 2160p60 | 50m |

Physical Characteristics

Connector: BNC (Bayonet Neill-Concelman) with positive locking

Cable: 75-ohm coaxial (RG-6 or Belden equivalent)

Termination: Proper termination critical for signal integrity

Loop-Through: Many devices support re-clocking and loop output

Why Professionals Choose SDI

Reliability: No handshaking or negotiation failures

Distance: 100m standard, extending further with signal boosters

Locking Connectors: BNC connectors cannot accidentally disconnect

Genlock Support: Embedded timing for multi-source synchronization

Embedded Audio: Up to 16 channels of digital audio in the video stream

Consistent Behavior: Same cable, same signal, predictable results

4K SDI Options

For 4K LED wall content:

12G-SDI: Single cable carries full 4K60, requires 12G-capable infrastructure

Quad-Link 3G-SDI: Four synchronized 3G cables carry 4K, works with existing 3G gear

Dual-Link 6G-SDI: Two cables for 4K, less common

SDI in LED Display Workflows

Typical professional LED wall signal flow:

1. **Source** (camera, media server) outputs SDI 2. **Video switcher** processes and routes SDI signals 3. **LED processor** receives SDI input 4. **Data conversion** transforms SDI to LED panel protocol

Processor SDI Considerations

When specifying LED processors for SDI workflows:

  • **Input Count**: Professional processors offer 4-8+ SDI inputs
  • **Standard Support**: Verify 3G-SDI minimum, 12G-SDI for 4K
  • **Genlock Input**: Required for broadcast synchronization
  • **Loop Output**: Useful for confidence monitoring
  • **Auto-Detection**: Seamless switching between SD/HD/3G signals

Cable and Infrastructure

Cable Quality: Use broadcast-grade coaxial (Belden 1694A or equivalent)

Connector Quality: Crimp or compression BNC with proper preparation

Testing: Use SDI signal generators and monitors to verify integrity

Labeling: Mark cable type (3G vs 12G capable) clearly

Patch Panels: Normalize connections for flexibility

SDI vs HDMI Decision

| Factor | SDI | HDMI | |--------|-----|------| | Max distance | 100m+ | 15m passive | | Connector | Locking BNC | Friction fit | | Cable cost | Moderate | Low | | Equipment cost | Higher | Lower | | Reliability | Excellent | Good | | Consumer device support | Via converter | Native |

Frequently Asked Questions

Why do broadcast productions prefer SDI over HDMI?

SDI provides reliable long-distance transmission (100m+ vs 15m for HDMI), locking BNC connectors that cannot accidentally disconnect, genlock support for multi-camera synchronization, and consistent behavior without EDID negotiation issues.

What SDI version do I need for my LED wall?

3G-SDI handles 1080p at 60Hz, sufficient for most LED walls. For 4K content, 12G-SDI carries full 4K60 on a single cable, or you can use Quad-Link 3G-SDI (four cables). Check your processor SDI input capabilities.

Can I convert HDMI sources to SDI for longer cable runs?

Yes, HDMI-to-SDI converters are common and cost $100-500 for quality units. This is standard practice for getting laptop or consumer device signals to distant LED processors. Ensure the converter supports your required resolution and frame rate.

Related Terms

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