IP cameras are widely used in public transport vehicles, enhancing onboard safety and security. ROQSTAR Ethernet switches seamlessly integrate with these cameras, ensuring optimal functionality and data transmission. However, IP cameras contribute significantly to the network traffic. To achieve a robust and reliable network infrastructure, proper video settings and meticulous network design are essential. In this article, we highlight the importance of video parameters and compression for efficient data handling and network optimization in public transport vehicles.
Video Compression Types
Video compression techniques play a pivotal role in the efficient storage, transmission, and playback of digital video content. With a wide range of compression standards available, it becomes crucial to understand the differences in bandwidth requirements and the associated advantages and disadvantages of each technique. For this, we will compare the bandwidth requirements and key features of uncompressed video, MJPEG, MPEG-2, MPEG-4, H.264, and H.265 video compression standards, enabling public transport operators to make informed decisions for optimizing their IP networks in buses and trams.
Uncompressed Video
Uncompressed video refers to raw video data stored without any compression. It is characterized by the highest possible quality but requires a significant amount of bandwidth to transmit and store. The bandwidth required for uncompressed video depends on factors such as resolution, frame rate, and color depth. While it offers unparalleled fidelity, the large file sizes and high bandwidth requirements limit its practicality for most applications.
MJPEG (Motion JPEG)
MJPEG compresses each frame of a video sequence as an individual JPEG image. While it retains individual frame quality, it lacks inter-frame compression, resulting in larger file sizes and higher bandwidth requirements. MJPEG provides simple and efficient encoding and decoding processes, making it suitable for certain applications. However, its high bandwidth requirements and relatively low compression efficiency make it less favourable for bandwidth-constrained scenarios.
MPEG-2 (Moving Picture Experts Group 2)
MPEG-2 is a widely used video compression standard primarily used in DVD-Video, digital television broadcasting, and satellite transmission. It provides a good balance between video quality and bandwidth efficiency. MPEG-2 achieves compression through various techniques, including spatial compression, temporal compression, and transform coding. The bandwidth requirements of MPEG-2 are lower compared to uncompressed video and MJPEG, making it suitable for various broadcast applications. However, its compression efficiency is inferior to newer standards, resulting in larger file sizes and limited compatibility with modern streaming platforms.
MPEG-4
MPEG-4 is a versatile video compression standard designed to handle a wide range of applications, including internet streaming, video conferencing, and multimedia storage. It offers improved compression efficiency compared to MPEG-2 while maintaining reasonable video quality. MPEG-4 achieves this through advanced techniques like object-based coding, which allows for more efficient representation of complex scenes. The bandwidth requirements of MPEG-4 are lower than those of MPEG-2, enabling smoother streaming experiences. However, MPEG-4 may exhibit some artifacts at lower bit rates, impacting visual quality.
H.264 (Advanced Video Coding)
H.264, also known as AVC (Advanced Video Coding), is a highly popular video compression standard widely used in applications such as Blu-ray discs, internet streaming, and video conferencing. It provides significant improvements in compression efficiency compared to MPEG-4, resulting in smaller file sizes and reduced bandwidth requirements. H.264 achieves this by employing advanced techniques such as inter-frame prediction and variable block-size motion compensation. These advancements make H.264 an excellent choice for high-quality video delivery. However, encoding and decoding H.264 videos can be computationally intensive, requiring powerful hardware for real-time encoding or decoding.
H.265 (High-Efficiency Video Coding)
H.265, also known as HEVC (High-Efficiency Video Coding), is the successor to H.264 and offers even higher compression efficiency. It achieves this through advanced techniques like larger block sizes, improved motion compensation, and enhanced entropy coding. H.265 can deliver video at roughly half the bit rate of H.264 while maintaining similar visual quality. The reduced bandwidth requirements make H.265 highly beneficial for applications such as 4K and 8K video streaming. However, encoding and decoding H.265 videos require more computational power compared to H.264, limiting its compatibility with older devices or systems.
Here are some typical examples of Bitrates for FHD (1920×1280) colour Images with 30FPS
- Uncompressed Video
Bitrate: 1920 x 1080 x 30 x 24 (bits per pixel) = 186,624,000 bits per second (bps) or 186.624 Mbps
- MJPEG
2.1 Low-quality: Bitrate: 10 – 20 Mbps (typical range). Example: 15 Mbps
2.2 Medium-quality: Bitrate: 20 – 40 Mbps (typical range). Example: 30 Mbps
2.3 High-quality: Bitrate: 40 – 80 Mbps (typical range). Example: 60 Mbps
- MPEG-2
Bitrate: 4 – 15 Mbps (typical range). Example: 8 Mbps - MPEG-4
Bitrate: 1 – 5 Mbps (typical range). Example: 3 Mbps - H.264 (AVC)
Bitrate: 0.5 – 10 Mbps (typical range). Example: 5 Mbps - H.265 (HEVC)
Bitrate: 0.2 – 8 Mbps (typical range). Example: 3 Mbps
The MJPEG compression standard is the only standard which utilizes Intra-frame compression only as it compresses individual frames independently. As a result, it focuses on image quality more than the compression rate. All the other compression standards use both Intra-Frame (every frame individually) and inter-frame (sequence of frames) algorithms and can reach more efficient compression rates. On the contrary the lack of inter-frame compression algorithms of the MJPEG makes it quite popular as it requires relatively small encoding and decoding computational power.
How to Optimize Data Handling in Vehicle IP Networks by Selecting the Right Ethernet Standard and Compression Techniques
In the realm of vehicle IP networks, efficient data handling is essential for optimal performance and scalability. One critical aspect is choosing the appropriate Ethernet standard speed to ensure seamless operations and accommodate future growth.
Two primary Ethernet standards commonly considered are Fast Ethernet, offering 100 Mbps, and Gigabit Ethernet, providing 1000 Mbps. Fast Ethernet offers lower costs and moderate speeds, while Gigabit Ethernet offers higher speed data transfer and scalability for future requirements.
>> Read also: Fast Ethernet or Gigabit Ethernet in Public Transport Networks?
To better understand the impact of different compression techniques on network traffic, we have compiled the following table. It presents the expected traffic in Mbps for a network segment, considering various compressions, while delivering Full HD (1920×1280) color images at 30 frames per second.
By considering both the Ethernet standard and compression techniques, you can make informed decisions to optimize data handling and ensure efficient operations in your vehicle IP network.
| # connected cameras | ||||||||
|---|---|---|---|---|---|---|---|---|
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | |
| MJPEG L | 15 | 30 | 45 | 60 | 75 | 90 | 105 | 120 |
| MJPEG M | 30 | 60 | 90 | 120 | 150 | 180 | 210 | 240 |
| MJPEG H | 60 | 120 | 180 | 240 | 300 | 360 | 420 | 480 |
| MPEG-2 | 8 | 16 | 24 | 32 | 40 | 48 | 56 | 64 |
| MPEG-4 | 3 | 6 | 9 | 12 | 15 | 18 | 21 | 24 |
| H.264 | 5 | 10 | 15 | 20 | 25 | 30 | 35 | 40 |
| H.265 | 3 | 6 | 9 | 12 | 15 | 18 | 21 | 24 |
Blue: Throughput can be handled with a Gigabit Ethernet port
Conclusion: Managing Video Streams in Vehicle Networks with Effective Compression Strategies
Optimizing data handling is crucial in vehicle IP networks for optimal performance and scalability. Choosing the appropriate Ethernet standard speed, like Fast Ethernet (100 Mbps) or Gigabit Ethernet (1000 Mbps), based on cost, speed, and future growth considerations, is essential. Video compression techniques also play a pivotal role in efficient storage, transmission, and playback of digital video content. Understanding the differences in bandwidth requirements and advantages of each compression standard is vital for network optimization. Uncompressed video offers the highest quality but requires significant bandwidth, while compression standards like MJPEG, MPEG-2, MPEG-4, H.264, and H.265 provide varying levels of compression efficiency, file sizes, and bandwidth requirements. Considering both the Ethernet standard and compression techniques ensures efficient data handling, network optimization, and improved performance in IP networks of public transport vehicles.
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