Video compression may seem really dull, but the real-world benefits of using the latest technology can radically increase the flexibility of your IP network. Sony H.264 cameras typically use one-fifth the bandwidth of cameras using older JPEG technology.
Put simply, better compression means greater flexibility – the more efficiently data is handled, the more choices you have with your existing resources. An existing network can support more cameras, better audio-video quality or both.
For surveillance applications, the ‘industry-standard’ image compression format is JPEG – which is perhaps best known for digital still photographs. In fact, using JPEG compression a network camera is acting rather like a digital camera – taking 25 (PAL) or 30 (NTSC) pictures per second. Each image is compressed individually (this is called intra-frame compression) which ensures each image is good quality and also provides a near constant data-size – making predicting network data traffic and data storage demands easy.
Often referred to as Motion JPEG or MJPEG, this form of compression has a relatively low processor demands and made possible the current generation of network cameras. It’s also quite well suited to monitoring applications where it’s not always essential to provide a TV-quality frame-rate. On the negative side, the MJPEG format dates back to the early 90s and since then the technology of compression has advanced considerably...
H.264 & hardware support
MPEG-4 compression not only operates on each individual frame (intra-frame compression) but also across a series of frames (inter-frame compression). Since a large amount of data is frequently unchanged between frames, this enables a highly significant increase in compression.
MPEG-4 is actually a series of standards, developed by ISO/IEC Motion Pictures Expert Group (MPEG), and MPEG-4 Part 2 is supported by most Sony network cameras. In 2006, however, Sony began introducing a more advanced MPEG-4 format known as H.264 (or MPEG-4 Part 10). Specifically developed to provide high quality video at a much lower bit rate than MPEG-4, it uses a variety of different advanced techniques to achieve this aim – most notably block patterns used to predict movement across video frames.
The practical benefits of these varying compression formats can be illustrated quite simply. In the above diagram you can see JPEG compression operating at 260Kb/s, while MPEG-4 transmits at 85Kb/s and H.264 transmits at 50K/bs. To put this into perspective, MPEG-4 requires approximately one-third of the bandwidth used by JPEG and H.264 requires just one-fifth.
Since H.264 compression is so advanced, it does demand more processing power than older formats, but as Sony network cameras natively support H.264 in hardware this doesn’t make any difference in operational terms.
Leadership & Compatibility
A five-fold increase in the capacity of an IP-based network might seem science fiction, but in a networked digital world it should come as no surprise that there’s huge amount of investment in ensuring the highest possible video quality at the lowest possible bitrate. H.264 technology is currently used in Blu-ray discs, HDTV broadcasting (including BBC HD and Euro 1080), AVCHD (a HD recording format for HDD and Solid State camcorders) and a wide variety of mobile devices, including Apple’s iPhone and Sony’s PSP. The format is also commonly used online for high quality content, for example HD movie trailers, and it's also been adopted by YouTube for its new high quality mode. This also means most media players, such as QuickTime or VLC, support H.264 encoded content.
Sony is at the heart of this networked digital world, in fact the Joint Video Team (JVT) Committee of which Sony is a long-standing member recently received an Emmy Engineering Award for its work on H.264/MPEG-4's High Profile compression standard. So it should be no surprise that Sony has played a leading role in bringing the most advanced technology to video security. The first Sony security cameras using H.264 compression were introduced in 2006. Two years later, the Sony range now has no less than seven cameras supporting H.264 – the widest range of cameras in the industry!
More information on Sony Video Security solutions
* The vertical axis shows Peak Signal-to-Noise Ratio (PSNR), a metric for the “quality” of compressed video images, while the horizontal axis shows the transmission bit rate. The graph shows just one example of comparing bit rates at which JPEG, MPEG-4, and H.264 images can be transmitted. Actual bit rates for transmitting data using these three compression formats differ with image quality and image size settings. In this example, the video parameters are; 10 frames per second, 176x144 (QCIF) resolution, 10 seconds of video (100 frames).