The relationship between code stream, code rate and frame rate and setting suggestions

Three concepts

• Resolution: The pixel size of the image, such as 1920×1080.
• Frame rate (fps): Number of images per second. 25fps is the mainstream in China, and 60fps is smoother but doubles the amount of data.
• Bit rate (bps): The amount of data transmitted/stored per second determines the detail of the image quality. Common 2Mbps, 4Mbps.

Simple understanding: Total data volume ≈ bit rate × time, and the bit rate is affected by resolution, frame rate, picture complexity and encoding algorithm.

Recommended parameter comparison (H.265)

How to determine the frame rate

• 25fps: Conventional monitoring, coherent picture, domestic standard.
• 15fps: There is basically no lag to the human eye. It can save about 40% of storage and is suitable for slow scenes such as corridors.
• 8～12fps: Obviously saves storage, but fast moving objects will feel like they are jumping.
• 60fps: Only used in special scenes where high-speed motion details need to be captured (such as production line inspection).

Optimization ideas

1. Use H.265 / H.265+ encoding first, which saves about 40% to 50% bit rate than H.264.
2. Static areas (such as warehouses and corridors) reduce the frame rate and bit rate, and dynamic entrances and exits maintain high bit rates.
3. Enable Dynamic Bitrate (VBR) to allow the bitrate to automatically adjust with the complexity of the image.
4. Set high bit rates individually for key channels, and use low bit rates for common channels to avoid "one size fits all".
5. Reasonably delineate motion detection areas to reduce invalid recordings.