When configuring camera parameters, we often encounter concepts such as frame rate, bitstream, and resolution. Newcomers to weak current engineering who are just getting started may not fully understand these terms. Today, let’s discuss the relationship between camera frame rate, bitstream, and resolution.

1. Definitions of Frame Rate, Bitstream, and Resolution

Frame rate refers to the number of images displayed per second. This concept frequently appears in camera specifications. For example, a camera with a frame rate of 25 fps means it displays 25 frames per second.Resolution indicates the size of each image, i.e., the number of pixels. A common example is a 2-megapixel camera, which has a resolution of 1920×1080.Bitstream refers to the data rate of video. Compression removes spatial and temporal redundancy from images.For nearly static scenes, a very low bitstream can deliver good image quality. For high-motion scenes, even a high bitstream may fail to achieve satisfactory quality.

Frame rate determines the smoothness and real-time performance of video. Resolution defines the size and clarity of the monitored image. The appropriate bitstream depends on storage capacity, network conditions, and specific video application scenarios.

2. Function of Bitstream

Bitstream, also known as bit rate, refers to the amount of video data transmitted per unit of time. It is the most critical factor for controlling image quality in video encoding.At the same resolution and frame rate, a higher video bitstream results in better image quality, but also requires larger storage space.

Relationship Between Frame Rate, Resolution and Bitstream ① Video Surveillance Storage Capacity Calculation The storage capacity of video surveillance is closely related to the bitstream. Currently, the mainstream camera encoding technologies mainly include **H.264** and **H.265**. Generally, a 1.3-megapixel camera with H.264 encoding has a bitstream of 2 Mbps, and a 2-megapixel camera has a bitstream of 4 Mbps. Cameras using H.265 encoding have **half the bitstream** of H.264 cameras, so the bitstream of a 2-megapixel camera is approximately 2 Mbps. Calculation Formula: Daily Recording Capacity (in GB) = Bitstream × 3600 × 24 ÷ 8 ÷ 1024 Example 1: How much hard disk capacity is required for 1 day of recording by a 2-megapixel H.264 camera? 4 Mbps × 3600 × 24 ÷ 8 ÷ 1024 = **42.19 GB** Example 2: How much hard disk capacity is required for 1 day of recording by a 2-megapixel H.265 camera? 2 Mbps × 3600 × 24 ÷ 8 ÷ 1024 = 21.10 GB Next, let’s talk about Triple-Stream Technology, which is closely associated with high-definition cameras. ② Triple-Stream Technology During encoding, high-definition network cameras generate **three streams: Main Stream, Sub Stream, and Third Stream. This concept was first proposed by Hikvision, a leading security manufacturer. - Main Stream: Mainly used for local high-definition video recording and storage. - Sub Stream: Mainly used for network video transmission. - Third Stream: Mainly used for mobile APP preview via cellular networks. By adopting Third Stream Technology, mobile devices can obtain smooth video images and recordings even over mobile networks.

Triple-Stream Technology 3. The Role of Frame Rate Frame rate refers to the number of frames transmitted and displayed per second. Each frame is a still image, and rapid consecutive frames create the effect of motion. A higher frame rate results in smoother and more realistic video. The higher the FPS (frames per second), the smoother the video motion, and the **higher the required bitrate**. For example, the frame rate for ordinary video surveillance is generally 25 fps, which is sufficiently smooth for typical scenes. However, for capture cameras on highways, 25 fps is often insufficient and may cause motion blur or trailing when capturing fast-moving vehicles. In such cases, high-frame-rate cameras are required, such as industrial cameras with 120 fps. 4. The Role of Resolution Resolution refers to the size or dimensions of an image, which we commonly encounter in displays and cameras. Common camera resolutions include: - 1920×960 (960P) - 1920×1080 (1080P) - 4K Ultra HD In the two numbers representing imaging, the first is the image width and the second is the height. Multiplying them gives the total pixels. For example, 1920×1080 represents 2 megapixels. Common aspect ratios are 4:3 and 16:9; in video surveillance, 16:9 is the dominant format. Summary When configuring camera parameters, we frequently encounter frame rate, bitrate, and resolution: - Frame rate: the number of images displayed per second; the standard in surveillance is typically 25 fps. - Bitrate: the volume of video data per unit time; a higher bitrate requires more storage space. - Resolution: the size or dimensions of the image; 1920×1080 means 2-megapixel HD. The most commonly used aspect ratio in video surveillance systems is 16:9.