GY/T 425-2025 in English

Background and Technological Evolution of Standard Development

GY/T 425-2025 "Technical Requirements and Measurement Methods for Broadcast-Grade Ultra-High-Definition Cameras" is an important standard document for China's broadcasting, television, and online audiovisual industries against the backdrop of the rapid development of ultra-high-definition technology. Released in 2025, this standard was jointly drafted by more than 20 organizations, including the Academy of Broadcasting Science of the State Administration of Radio and Television and China Media Group, marking a new stage in the standardization of ultra-high-definition camera technology in China.

Compared with the GY/T 295-2015 high-definition camera standard, the major breakthroughs of this standard are reflected in: the resolution being upgraded from high-definition to 8K/4K ultra-high-definition, the dynamic range being expanded from SDR to HDR, and the interface standard being upgraded from 3G-SDI to 12G-SDI and IP streaming media.

This technological evolution aligns with the global trend of ultra-high-definition video industry development, providing unified technical specifications for domestic ultra-high-definition program production. The standard clearly classifies broadcast-grade ultra-high-definition cameras into two main types: ultra-high-definition studio cameras (electronic field production cameras) and ultra-high-definition electronic news gathering cameras. Both types of cameras require resolutions of 8K (7680×4320) and 4K (3840×2160), and the signal format must comply with GB/T 41808-2022.

Functional Category	Studio Camera Requirements	News Gathering Camera Requirements	Technical Difference Analysis
Control Method	Supports camera control unit connection and control	Features standard menu reset function	Studios emphasize remote control, news gathering emphasizes ease of operation
Recording Function	No built-in recording requirement	Requires recording and storage function	News gathering requires independent working capability
Interface Configuration	SDI or IP interface (choose one)	SDI, IP, HDMI (choose one)	More flexible and diverse news acquisition interfaces
Alarm function	Not required	Media storage, battery capacity, and device fault alarms	News acquisition emphasizes on-site reliability

Regarding photoelectric conversion functions, both types of cameras are required to have HLG or PQ HDR functions, while also being compatible with the SDR standard. Color gamut support must comply with the color gamut space specified in GB/T 41809-2022 to ensure the accuracy and consistency of color reproduction.

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In-depth analysis of photoelectric performance indicators

The standard divides photoelectric performance into two levels, Class A and Class B, providing differentiated technical requirements for different application scenarios. The sensitivity requirement is ≥F8 for all three photoelectric conversion functions, reflecting a high degree of emphasis on shooting capabilities in low-light environments.

Performance Indicators	Class A Requirements	Class B Requirements	Test Conditions
Dynamic Range	≥13 stops (HDR)	≥12 stops (HDR)	Inflection Point Enabled, Gain 0dB
Center Sharpness	8K≥3600TVL 4K≥2000TVL	8K≥3200TVL 4K≥1800TVL	Gain 0dB, Detail Enabled
Brightness Channel Signal-to-Noise Ratio	≥60dB	≥54dB	Gain 0dB, Noise Reduction Off
Defect Requirements	No Defects		Inspection under Different Gain Conditions

Dynamic range testing uses a 21-level grayscale test chart. By adjusting the inflection point position and compression ratio, the maximum number of distinguishable grayscale levels is read on an ultra-high-definition waveform analyzer. This indicator is directly related to the camera's detail performance in high-contrast scenes.

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Output Interface Technical Specifications

The standard specifies detailed technical requirements for three main output interfaces: 3Gbps-SDI, 12Gbps-SDI, and IP interface.

The rise/fall time requirement of the 12Gbps-SDI interface is ≤45ps, which is a significant improvement over the 135ps of the 3Gbps-SDI interface, reflecting the strict requirements of ultra-high-definition signal transmission for timing accuracy.

Interface Parameters	3Gbps-SDI Requirements	12Gbps-SDI Requirements	Technical Significance
Signal Amplitude	800mV±80mV	800mV±80mV	Ensuring Signal Transmission Stability
Rise Time	≤135ps	≤45ps	High Frequency Signal Integrity Guarantee
Jitter (100kHz)	≤0.3UI	≤0.3UI	Clock Synchronization Accuracy Requirements
Link Delay Difference	≤400ns	≤250ns	Key Parameters for Multi-Link Synchronization

IP output interface requirements comply with GY/T 414-2024 (video), SMPTE ST 2110-30:2017 (audio) and SMPTE ST 2110-40:2018 (auxiliary data) standards, with a dual-channel IP output delay difference not exceeding 150μs, providing technical assurance for IP-based production and broadcasting systems.

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Audio Performance Index Analysis

The standard sets forth clear requirements for the audio performance of ultra-high-definition electronic news acquisition cameras, divided into two categories: microphone signal input and line signal input. The signal-to-noise ratio requirement for line input is ≥75dB, significantly higher than the ≥60dB requirement for microphone input, reflecting the differentiated requirements for the quality of different signal sources.

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Significance of Standardization of Measurement Methods

Chapter 6 of the standard details the measurement methods for various technical indicators, including measurement environmental conditions, equipment connection methods, and specific operating procedures. The measurement environment requires a temperature of 15℃～35℃, relative humidity of 10%～90%, and air pressure of 86kPa～106kPa to ensure the comparability and repeatability of test results.

Photoelectric performance measurements must be conducted in an optical darkroom, with an illuminance of 2000lx±20lx when using a reflective test card, and a white block reflectance of 89.9%. These standardized testing conditions provide a unified benchmark for comparing the performance of equipment from different manufacturers, promoting the overall improvement of the industry's technical level.

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Standard Implementation Recommendations and Outlook

Based on the content of GY/T 425-2025 standard, the following recommendations are made for the development of the ultra-high-definition camera industry:

Application Areas	Equipment Selection Recommendations	Key Performance Considerations	Testing and Acceptance Points
Broadcast and Television Production	Class A Studio Camera	Dynamic Range, Signal-to-Noise Ratio	Multi-Link Delay Synchronization
News Scene Acquisition	Class B News Acquisition Camera	Recording Reliability, Ease of Operation	Comprehensive Audio Performance Testing
Live Broadcast of Large-Scale Events	Class A Studio Camera	Sensitivity, Overall Transmission Distance	Long-Distance Transmission Stability
Film and Television Production	Class A News Gathering Camera	Color Reproduction, Detail Performance	HDR/SDR Compatibility

With the continuous development of ultra-high-definition technology, future standards may further evolve towards 8K 120fps high frame rate, wider color gamut Rec.2020, and AI-based image optimization. GY/T 425-2025 lays a solid standardization foundation for this technological evolution and will strongly promote the high-quality development of China's ultra-high-definition video industry.