Category: reference

Color Subsampling is a compression method that reduces the resolution of color data while retaining the brightness (luminance) data at full resolution.

It is widely used in video compression to reduce data size with minimal visual loss, as the human eye is more sensitive to brightness than color.

Types of Chroma Subsampling

4:4:4 – No Subsampling

• In this format, both brightness (Y) and color channels (Cb and Cr) maintain full resolution, meaning each pixel has individual color and brightness data.
• This format offers the highest quality and is commonly used in professional editing and color correction.

4:2:2 – Horizontal Half Subsampling

• Here, color channels (Cb and Cr) are sampled at half the horizontal resolution, while brightness remains at full resolution.
• Commonly used for broadcasting and professional video as it provides high quality with moderate data reduction.

4:2:0 – Horizontal and Vertical Half Subsampling

• Color resolution is reduced both horizontally and vertically while brightness remains at full resolution.
• Widely used in consumer video formats such as Blu-ray and streaming, as it achieves significant data compression while preserving acceptable visual quality.
  

There is one more format: 4:1:1
It’s rarely used today but was once found in some professional formats like NTSC DV.

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Naming

In chroma subsampling notation, such as 4:4:4, 4:2:2, and 4:2:0, each number represents how brightness and color data are recorded:

• The first digit is always “4” and indicates the sampling rate of luminance (brightness) horizontally, covering each pixel.
• The second digit shows the horizontal sampling of chrominance (color).
• The third digit indicates the vertical sampling of chrominance.

This subsampling reduces data size because human eyes are more sensitive to brightness than color, allowing for efficient compression without noticeable quality loss.

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Comparison of formats

Format	Brightness (Y)	Color (Cb and Cr)	Use Cases
4:4:4	Full	Full	High-quality editing and color correction
4:2:2	Full	Half horizontal	Broadcast and professional video
4:2:0	Full	Half horizontal and vertical	Consumer video, Blu-ray, streaming

Each format caters to different needs, balancing quality and data efficiency based on the requirements of the specific video application.

Framelock – Synchronization of Video Streams Across Multiple Display Devices

When video content is displayed on multiple screens, it is crucial that all screens show the frames simultaneously.

Framelock helps create a virtual canvas where the continuity of the image is maintained across all screens. This involves the use of hardware devices.

Synchronization can occur both within a single GPU and across multiple GPUs.

The following GPUs have built-in Framelock capabilities:

• Quadro/A/ADA series for NVIDIA
• FirePro/Radeon Pro series for AMD

For combining multiple GPUs in one or several PCs, synchronization cards are used:

• Quadro Sync for NVIDIA
• FirePro S400 for AMD

One synchronization card can connect up to 4 GPUs in a single PC and can also send the sync signal to the next synchronization card via UTP.

These cards can also receive a Genlock sync pulse through a BNC connector.

Providing framelock sync for GPU

Nvidia Sync and AMD s400 Sync cards

COntents:

• How Genlock Works
• Genlock Applications
• Blackburst / Tri-Level Sync
• Popular Devices

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Genlock is a technology used for synchronizing video equipment so that all devices operate in sync with the same timing. Genlock ensures that various devices, such as cameras, media servers, and video players, are synchronized with a common timing source, preventing issues like image tearing or stuttering.

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How Genlock Works

Genlock transmits a clock signal (sync pulse) from one device to another, forcing them to operate at the same frame rate and synchronize their timing. This is particularly important in professional video production, where multiple cameras, video mixers, media servers, and other devices need to be precisely synchronized.

On different devices, you may encounter terms like Reference, Sync Reference, or External Sync.

It is important to know that the reference sync signal is an analog signal and will require an analog distribution amplifier if a larger number of channels is needed.

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Genlock Applications

Cameras:

• Video Production: In multi-camera systems, such as in television studios or live broadcasts, Genlock is used to ensure that all cameras capture frames simultaneously. This is crucial to avoid delays or tearing when switching between cameras.
• Multi-Camera Shooting: When using multiple cameras to capture the same event, Genlock helps synchronize them so that each frame captured by each camera has the same timing.

Media Servers:

• Output Synchronization: Media servers using Genlock can synchronize their output video streams with an external sync source, such as a camera or another server. This is critical when using media servers for projection across multiple screens or for real-time video streaming.
• Cooperation Between Multiple Servers: When several media servers are used to output video to different screens, Genlock ensures that all servers output images in sync, avoiding mismatches or lags.

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Blackburst / Tri-Level Sync

Blackburst and Tri-Level Sync are two different types of sync signals used for synchronizing video equipment in professional video systems.

Blackburst

What It Is:
Blackburst, also known as color burst or video sync pulse, is an analog video signal that carries a black frame with synchronization pulses and a color subcarrier. This signal is used to ensure that video devices are synchronized.

Usage:
Blackburst is primarily used in SD (Standard Definition, e.g., 480i) systems and sometimes in HD (High Definition) systems. It was the standard for synchronizing analog video equipment and is still used in some legacy systems.

Features:
Blackburst provides vertical and horizontal synchronization as well as color synchronization through the color subcarrier signal. This type of signal is simple and effective for basic synchronization in standard definition systems.

Tri-Level Sync

What It Is:
Tri-Level Sync is a synchronization signal that uses three voltage levels (positive, zero, and negative) to create a more precise and stable sync signal compared to Blackburst. It provides greater accuracy and reliability in synchronization.

Usage:
Tri-Level Sync is used in high-resolution systems like HD (1080p) and 4K, where more precise synchronization is required. It is the standard sync signal for digital video systems and high-resolution equipment.

Features:
Tri-Level Sync generates sync pulses at a higher frequency, making it the preferred choice for minimizing jitter and ensuring precise frame alignment in high-resolution video systems.

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Genlock Generation

Special devices are used to generate Genlock, creating a synchronization signal that is transmitted to all connected devices.

Popular Devices:

AJA GEN10:
A sync generator supporting SD, HD, and 3G-SDI. It can be used to synchronize video equipment, including cameras and media servers.

Blackmagic Design Sync Generator:
A simple device for generating Genlock with SDI support. It generates stable clock signals and is used in professional studios for equipment synchronization.

Rosendahl Studiotechnik Nanosyncs HD:
A compact and powerful sync generator supporting HD and SD formats. It is used for precise synchronization of video equipment in studio environments.

Contents:

• Types of Optical Fiber Cables
• Bandwidth Capacity
• Types of Connectors

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Optical fiber cable is a cable designed to transmit data through light pulses that travel through thin glass or plastic fibers. The primary advantage of optical fiber cables over copper cables is their high bandwidth capacity and resistance to electromagnetic interference.

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Types of Optical Fiber Cables

Single-Mode (SM)

• Working Principle: A single laser light beam travels through the center of the fiber.
• Core Diameter: Typically around 8-10 microns.
• Application: Used for long distances and high-speed data transmission.
• Advantages: Lower attenuation and the ability to transmit data over longer distances.

Multi-Mode (MM)

• Working Principle: Multiple light beams travel through the fiber at different angles.
• Core Diameter: Typically around 50-62.5 microns.
• Application: Used for short to medium distances, often in building infrastructures and local area networks (LANs).
• Advantages: Cheaper transmitters and receivers.

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Bandwidth Capacity

The bandwidth capacity of optical fiber cables depends on several factors, including the type of fiber, transmission technologies used, and distance.

Cable Type	Subtype	Max Distance	Max Data Rate
SM	OS1	Up to 10km	Up to 10 Gbps
SM	OS2	Up to 200km	10 Gbps / Up to 100 Gbps with WDM
MM	OM1	Up to 300m	Up to 1 Gbps
MM	OM2	Up to 550m	Up to 10 Gbps
MM	OM3	Up to 300m	Up to 10 Gbps
MM	OM4	Up to 400m	Up to 10 Gbps
MM	OM5	Up to 150m	Up to 100 Gbps (using WDM)

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Types of Connectors

1. SC (Subscriber Connector)
   • Connector Type: Push-pull.
   • Application: Widely used in data transmission and telecommunications networks.
   • Features: Easy to use and provides reliable connections.
2. LC (Lucent Connector)
   • Connector Type: Push-pull.
   • Application: Commonly used in modern optical networks due to its compact size.
   • Features: Compact design, suitable for high-density connections.
3. ST (Straight Tip)
   • Connector Type: Bayonet.
   • Application: Frequently used in campus and corporate networks.
   • Features: Easy to install and remove thanks to the bayonet coupling mechanism.
4. FC (Ferrule Connector)
   • Connector Type: Threaded.
   • Application: Widely used in telecommunications and measurement equipment.
   • Features: Reliable connections due to threaded coupling.
5. MTP/MPO (Multi-Fiber Push On/Pull Off)
   • Connector Type: Push-pull.
   • Application: Used for connecting multi-mode fibers, often in data centers.
   • Features: Can connect up to 12 or even 24 fibers simultaneously, allowing for significantly higher connection density.

Contents:

• What is SRT protocol
• How SRT works
• Quick Guide to Setting Up SRT

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SRT: Secure Reliable Transport

SRT – a data transmission protocol based on UDP. It is an open-source project developed by Haivision.

SRT Alliance has over 500 members, including Haivision, Sony, Microsoft, Wowza, Panasonic, AVID, AJA, Matrox, BirdDog, Magewell, and Telestream.

Advantages:

• Low latency
• Original quality
• Stream security
• Firewall transparency
• Route redundancy
• Support for any codec

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Unlike other protocols, SRT checks for lost packets and retransmits them.

The protocol developers compared SRT and RTMP under real conditions:

• In latency tests, SRT was 2.5 to 3.2 times faster (depending on the distance between the sender and receiver).
• When using SRT, the maximum speed of 20 Mbps was maintained when transmitting data to any region in the world. With RTMP, the speed decreased with distance. For example, transmission from Europe to Australia showed a speed of no more than 2 Mbps.

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Quick Guide to Setting Up SRT

1. Install the Required Software

• Ensure you have installed and properly configured software that supports the SRT protocol, such as OBS Studio with the SRT plugin, VLC, or media servers like Wowza Streaming Engine.

2. Determine Connection Parameters

• IP Address and Port: Identify the IP address and port that will be used for data transmission. For example, 192.168.1.100:5000.
• Mode of Operation: Choose the SRT mode of operation:
  • Caller: Initiates the connection to another device.
  • Listener: Waits for an incoming connection from another device.
  • Rendezvous: Both devices simultaneously initiate a connection to each other.

3. Configure SRT on the Sending Side

• Enter the IP address and port of the receiver.
• Choose the “Caller” mode.
• Configure encryption settings if required (AES 128/256 bit).
• Set buffering and latency parameters according to the network quality.

4. Configure SRT on the Receiving Side

• Specify the IP address and port where the stream will be received.
• Choose the “Listener” mode.
• Configure encryption settings to match those on the sending side.
• Ensure that the firewall and router are configured to allow traffic through the specified port.

5. Check the Connection

• Start streaming on the sending side.
• Ensure that the stream is successfully received on the receiving side.

6. Monitoring and Optimization

• Use built-in monitoring tools in the software to check the quality of the stream, delays, and packet loss.
• Adjust buffering and latency settings as necessary to optimize transmission quality.

Example Configuration in OBS Studio:

On the Sending Side (Caller):

1. Open OBS Studio.
2. Go to “Settings” -> “Stream”.
3. Select “Custom” under the “Service” section.
4. Enter srt://:?mode=caller (e.g., srt://192.168.1.100:5000?mode=caller).
5. Configure encryption and buffering parameters if necessary.
6. Click “OK” and start streaming.

On the Receiving Side (Listener):

1. Open OBS Studio.
2. Go to “Settings” -> “Stream”.
3. Select “Custom” under the “Service” section.
4. Enter srt://:?mode=listener (e.g., srt://0.0.0.0:5000?mode=listener).
5. Configure encryption and buffering parameters if necessary.
6. Click “OK” and start receiving the stream.

This way, you can set up and use SRT for reliable and secure video streaming with low latency.

Contents:

• Comparison of Connector Types
• Photos of Connectors and Distributors
• Useful Calculation Formulas

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The most popular electrical connectors are considered to be CEE, Socapex, and Powerlock.

Name	Phases	Amperes	KiloWatts
CEE 16A	1-3	16	Up to 3.7 (single-phase) 11 (three-phase)
CEE 32A	1-3	32	Up to 7.4 (single-phase) 22 (three-phase)
CEE 63A	1-3	63	Up to 14.5 (single-phase) 43 (three-phase)
CEE 125A	1-3	125	Up to 28.8 (single-phase), 86 (three-phase)
Socapex	1	16 (per pin)	Depends on configuration
Powerlock	1-3	Up to 400	Up to 96 (single-phase) 277 (three-phase)

Number of Phases: CEE connectors can be single-phase or three-phase. Socapex connectors are usually single-phase but have many contacts. Powerlock connectors can be either single-phase or three-phase.

Kilowatt Rating: Power (in kilowatts) is calculated based on the standard voltages of 230V (single-phase) and 400V (three-phase). Actual values may vary depending on operating conditions.

Standard: CEE connectors comply with the IEC 60309 standard. Socapex connectors do not have a specific international standard but are widely used in the stage industry. Powerlock connectors comply with the BS EN/IEC 61984 standard.

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Useful Formulas

To calculate power in kilowatts (kW) based on the current (in amperes, A) and voltage (in volts, V), the following formulas are used:

SINGLE-PHASE CONNECTION

P(kW) = V(Volts) × I(Amperes)​ / 1000

Example:
P(kW) = 230 × 16​ / 1000
P(kW) = 3.68

THREE-PHASE CONNECTION

P(kW) = 3  × V(Volts) × I(Amperes)​ / 1000

3 = 1.732

Example:
P(kW) = 1.732 × 380 × 32​ / 1000
P(kW) = 21.06

If you know the power in kilowatts (kW) and want to calculate the current in amperes (A), you can use the following formulas for single-phase and three-phase systems:

SINGLE-PHASE CONNECTION

I(Amperes) = P(kW) × 1000 / V(Volts)​

Example:
I(Amperes) = 3.68 × 1000​ / 230
I(Amperes) = 16

THREE-PHASE CONNECTION

I(Amperes) = P(kW) × 1000 / 3 ​× V(Volts)​

3 = 1.732

Example:
I(Amperes) = 21.06  × 1000 / 1.732 × 380
I(Amperes) = 32

PCIe (Peripheral Component Interconnect Express) is a high-speed interface for connecting components to a motherboard, such as graphics cards, SSDs, and network cards.

Key Features of PCIe:

• Speed: PCIe offers high data transfer rates significantly surpassing previous standards (PCI, PCI-X).
• Scalability: It uses lanes for data transmission (from x1 to x16), allowing the interface to be adapted for various needs.
• Compatibility: PCIe is backward compatible with earlier versions, enabling older devices to work on new motherboards.

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Release	Generation	x4	x8	x16
2003	PCIe 1.x	10	20	40
2007	PCIe 2.x	20	40	80
2010	PCIe 3.x	32	64	128
2017	PCIe 4.x	64	128	256
2019	PCIe 5.x	128	256	512
2022	PCIe 6.x	256	512	1024

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PCIe-Lanes

PCIe lanes are the fundamental data transmission channels in the PCIe interface. Each lane consists of two pairs of wires, allowing data to be transmitted simultaneously in both directions (input and output), making PCIe a duplex interface.

PCIe lanes play a crucial role in determining the performance and connectivity capabilities of various components in modern computer systems.

CPU	Type	Chipset	CPU Lanes	Chipset Lanes
Coffee Lake Intel 8th/9th	Regular	Z390, H370, B360	16 (PCIe 3.0)	24 (PCIe 3.0)
Comet Lake Intel 10th	Regular	Z490, H470, B460	20 (PCIe 3.0)	24 (PCIe 4.0)
Comet Lake X Intel 10th	Regular	Z490, H470	44 (PCIe 3.0)	24 (PCIe 4.0)
Rocket Lake Intel 11th	Regular	Z590, H570, B560	20 (PCIe 4.0)	24 (PCIe 4.0)
Alder Lake Intel 12th	Regular	Z690, B660	20 (PCIe 4.0)	16 (PCIe 4.0)
Raptor Lake Intel 13th	Regular	Z790, B760	24 (PCIe 5.0)	16 (PCIe 5.0)
Raptor Lake Refresh Intel 14th	Regular	Z890, B860	24 (PCIe 5.0)	16 (PCIe 5.0)
Xeon Scalable (1st Gen)	Server	C620	28 (PCIe 3.0)	6 (PCIe 3.0)
Xeon Scalable (2nd Gen)	Server	C620	48 (PCIe 3.0)	6 (PCIe 3.0)
Xeon Scalable (3rd Gen)	Server	C620	64 (PCIe 3.0)	6 (PCIe 3.0)
Xeon Scalable (4th Gen)	Server	C740	64 (PCIe 4.0)	6 (PCIe 4.0)
Ryzen 3000	Regular	X570, B550	24 (PCIe 4.0)	8 (PCIe 4.0)
Ryzen 5000	Regular	X570, B550	24 (PCIe 4.0)	8 (PCIe 4.0)
Ryzen 7000	Regular	X670, B650	28 (PCIe 5.0)	8 (PCIe 5.0)
EPYC 7001	Server	SP3	128 (PCIe 3.0)	24 (PCIe 3.0)
EPYC 7002	Server	SP3	128 (PCIe 4.0)	24 (PCIe 4.0)
EPYC 7003	Server	SP3	128 (PCIe 4.0)	24 (PCIe 4.0)

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For more info about Pcie lines, read my detailed guide to building a media server

LED screens operate on the principle of light modulation. Each pixel consists of three basic LEDs (red, green, and blue), which can be turned on or off and can also adjust brightness. By mixing the light from these LEDs, the screen can create a variety of colors and display images.

There are two types of LED screen cabinets:

Indoor
Designed for use indoors, they have high resolution and brightness.
Advantages: High image quality and color reproduction, low brightness.

Outdoor
Designed for use outdoors, they have enhanced protection against moisture and dust (IP65 standard and above) and high brightness.
Advantages: Good visibility in sunlight and resistance to weather conditions.

Brand	Country
NovaStar	China
Linsn	China
Colorlight	China
HollyLite	China
Dicolor	China
Mediacore	China
Xunwei	China
Vanch	China
BrightSign	USA
Barco	Belgium

Types of Pixel Production Technologies

1. SMD (Surface-Mounted Device)
   LEDs are mounted on the surface of the printed circuit board, providing high pixel density and image clarity.
   Application: Used in various types of LED screens, including indoor and outdoor models.
2. DIP (Dual In-Line Package)
   LEDs are housed in plastic packages and placed on the printed circuit board. They are less suitable for high resolutions but are clearly visible from long distances.
   Application: Commonly used in advertising billboards and outdoor screens.
3. COB (Chip on Board)
   LEDs are placed directly on the printed circuit board, improving heat dissipation and brightness.
   Application: Used in high-quality displays and digital signage.
4. Mini LED
   Utilizes smaller LEDs, allowing for increased pixel density and improved image quality.
   Application: Used in premium LED screens and displays for televisions.

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USEFUL FORMULAS

How to determine the pixel pitch of a cabinet:

Width (mm) / Number of pixels
500mm / 200px = 2.5mm
Pixel pitch = 2.5mm


How to determine the optimal distance to the screen:

Pixel pitch * 1.5
3mm * 1.5 = 4.5m
Optimal distance to the screen = at least 4.5m

EDID (Extended Display Identification Data) is information that allows devices (such as computers, media players, and gaming consoles) to interact with displays (monitors, televisions, and projectors) for optimal adjustment of video and audio output parameters.

Structure of EDID

• Manufacturer Identification: Data about the display manufacturer, its model, and serial number.
• Supported Resolutions: A list of resolutions that the display supports, including the maximum resolution and refresh rate (for example, 1920×1080 @ 60Hz).
• Color Palette: Information about supported colors and color spaces (such as sRGB, Adobe RGB).
• Supported Audio Formats: If the display supports audio output, EDID may include information about supported audio formats.
• Specifications: Additional information, such as screen size, support for various modes (such as 3D), and other characteristics.

Operating Principle

The signal source (GPU/splitter/controller) makes a request to the display device (monitor/sending card), receives a data table in response, interprets it, and sends a signal corresponding to the data.

Modern graphics cards allow the emulation of arbitrary resolutions, bypassing the EDID data.

Example: In the NVIDIA Control Panel, under the Resolution Changes section –> Create Custom Resolution.

Professional graphics cards in the “Quadro/A” series from Nvidia and “FirePro/AMD Pro” from ATI/AMD have the ability to forcefully embed data at the output from the graphics card, which will not depend on external factors and will be retained even if the display device is turned off.

To emulate or modify EDID, there are both hardware and software solutions available, which can be found among manufacturers like Analog Way, Extron, Kramer, Lightware, as well as from various Chinese noname brands.

An Ethernet cable is a type of cable used for wired connections in local area networks (LAN), such as computers, routers, switches, and other network devices. It transmits data using electrical signals and ensures high-speed and reliable data transmission.

Cat-5	100 Mbps up to 100m
Cat-5e	1 Gbps up to 100m
CAT6	10 Gbps up to 55m
CAT6a	10 Gbps up to 100m
CAT7	10 Gbps up to 100m
CAT8	25 Gbps up to 100m 40 Gbps up to 30m

Ethernet cable types

• UTP (Unshielded Twisted Pair):
  No shielding, minimal interference protection. Used in low-interference environments like offices and homes.
• FTP (Foiled Twisted Pair):
  Overall foil shielding provides medium protection against electromagnetic interference. Suitable for environments with moderate levels of interference.
• SFTP (Shielded and Foiled Twisted Pair):
  Double shielding with foil and braided layers offers high protection against interference. Suitable for high-interference environments.
• STP (Shielded Twisted Pair):
  Each pair of wires has individual shielding, providing high protection against interference. Used in high-interference environments.
• ScTP (Screened Twisted Pair):
  Also known as F/UTP, it has overall foil shielding without individual pair shielding, providing medium protection against interference. Used in moderate-interference environments.
• PiMF (Pairs in Metal Foil):
  Each pair of wires is individually wrapped in foil, offering very high protection against crosstalk and external interference. Suitable for high-performance applications and high-interference environments like data centers and industrial settings.

Cable Type	Full Name	Shielding
UTP	Unshielded Twisted Pair	No shielding
FTP	Foiled Twisted Pair	Overall foil shielding
SFTP	Shielded and Foiled Twisted Pair	Double shielding: foil and braided
STP	Shielded Twisted Pair	Individual shielding for each pair
ScTP	Screened Twisted Pair	Overall foil shielding (F/UTP)
PiMF	Pairs in Metal Foil	Individual foil shielding for each pair

Cable Crimping

Crimping a cable is the process of attaching an RJ-45 connector to the cable ends to connect network devices. There are two main crimping standards: T568A and T568B, which determine the order of the conductors in the connector.

If you are unsure which standard to use, crimping according to T568B is a safe choice)