Video Transmission Formats Explained

SDI (Serial Digital Interface)

This is a professional video standard that transmits uncompressed digital video, audio, and metadata over coaxial cable using BNC connectors.

• Digital & Uncompressed: High-quality signal with low latency.

• Embedded Audio: Up to 16 channels.

• Common in Broadcast: Reliable and rugged for pro use.

Resolutions supported range from SD-SDI @ 480i / 576i up to 12G-SDI @ 4K

Transmission Length on coaxial cable varies based on resolution but is generally around 100M

Composite Video

 This analogue video signal combines luminance (brightness) and chrominance (colour) into a single channel, typically transmitted over RCA and BNC connectors.

• Analog Signal: Standard definition only.

• Single Cable: Carries both brightness and colour info.

• No Audio: Audio requires separate cables.

• Prone to Interference: Lower quality than S-Video or RGB.

Resolutions supported

• NTSC: 480i (typically 29.97 fps)

• PAL: 576i (typically 25 fps)

Transmission Length on coaxial BNC cable can be up to 300M

S-Video (Separate Video)

This analogue video signal splits luminance (Y) and chrominance (C) into two separate channels for improved image quality over composite video.

• Analog Signal: Standard definition only

• Improved Clarity: Better than composite, but below RGB

• No Audio: Audio must be run separately

• Mini-DIN Connector: Typically a 4-pin plug

Resolutions supported

• NTSC: 480i (typically 29.97 fps)

• PAL: 576i (typically 25 fps)

Transmission Length can be up to 50M

Analogue RGB

 This transmits video using three separate signals: Red, Green, and Blue, along with optional sync signals. It offers high-quality analogue video and is commonly used in older CRT monitors and some broadcast gear.

• High-Quality Analogue: Superior image quality compared to composite/S-Video

• Separate Color Channels: Minimal color bleed

• No Audio: Requires separate audio connections

• Sync Options: Sync can be combined (RGsB) or separate (RGBS)

Resolutions supported

• NTSC: 480i (typically 29.97 fps)

• PAL: 576i (typically 25 fps)

Transmission Length can be up to 50M

VGA (Video Graphics Array)

This is an analogue video standard developed for computers. It carries RGB video with seperate horizontal and vertical sync over a single cable.

• Analogue Signal: Good quality, but susceptible to degradation over long runs

• No Audio: Video-only — audio must be run separately

• Widespread Use: Common on older PCs, monitors, projectors, and KVMs

• RGBHV Format: Red, Green, Blue + Horizontal & Vertical Sync

Resolutions supported

• Originally: 640×480 (VGA)

• Can support up to: 1920×1080 (1080p)

Transmission Length can be up to 50M

DVI (Digital Visual Interface)

 This is a video standard designed to carry high-quality video from a source (like a computer) to a display. It supports digital, analog, or both, depending on the type.

• Digital & Analog Support:

  • DVI-D: Digital only

  • DVI-A: Analog only

  • DVI-I: Integrated (both digital and analog)

• No Audio: Video-only (unlike HDMI)

• Digital Signal = Sharper Image

• Compatible with HDMI (via adapters, video only)

Resolutions supported

• Single-Link DVI: Up to 1920×1200 @ 60Hz

• Dual-Link DVI: Up to 2560×1600 @ 60Hz

Transmission Length can be up to 15M

HDMI (High-Definition Multimedia Interface)

This is a widely used digital standard that carries high-quality video and audio over a single cable — commonly found in TVs, monitors, game consoles, and more.

• Digital Signal: High-definition video and multi-channel audio

• All-in-One: Video, audio, and control signals (like CEC)

• Supports HDCP: For protected content (e.g. Blu-ray, streaming)

• Backward Compatible: With DVI video (via adapter, no audio)

Resolutions supported

Varies by version:

• HDMI 1.4: Up to 4K @ 30Hz

• HDMI 2.0: Up to 4K @ 60Hz

• HDMI 2.1: Up to 8K @ 60Hz or 4K @ 120Hz

Transmission Length can be up to 15M

DisplayPort

 This is a digital display interface developed primarily for computers, designed to carry high-resolution video and audio, along with other data — all over a single cable.

• Digital Signal: High-quality video and multi-channel audio

• High Bandwidth: Ideal for high-res monitors and multi-display setups

• Supports Audio, USB, and Data over a single cable

• Daisy-Chaining: Via Multi-Stream Transport (MST)

• Adapts to HDMI, DVI, VGA (with appropriate converters)

Resolutions supported

Depends on version:

• 1.2: Up to 4K @ 60Hz

• 1.4: Up to 8K @ 60Hz (with compression)

• 2.0 / 2.1: Up to 16K or 4K @ 240Hz

Transmission Length can be up to 15M