At present, driven by better display and memory technologies, and the upcoming deadline for digital TV broadcasting in North America, the development of high-definition video is rapidly rising. Recent advances in technology have made it possible to introduce new video features from many devices ranging from small mobile phones to MP3 players to video walls and billboards. For video system designers, tempted by wider screens and higher resolutions, coupled with the strong support for the technology that is already mature and being deployed, all they have to do now is how to implement high definition (HD) ) Of various problems.
It is important to fully understand the content contained in HD, because there are many display formats that can be called high definition (HD). However, for some specific applications, some of the formats may not even be suitable for all formats. Televisions with new digital formats are an important application, but each type of display is a potential target for gradual upgrade technology. For developers, the real question is not only whether HD is required, but how to achieve the best possible display effect given the system's display, bandwidth, storage capacity constraints and cost constraints.
Any change in the technical field involves many problems, and the impact of some problems is not immediately apparent to system developers. Here are some things to keep in mind when doing HD R & D.
should
* Realize that HD format has greater system requirements. The data volume of the decompressed 1080i60 video is six times that of the decompressed SD video, so it can be roughly said that the system must provide six times the processing power and storage capacity. In addition, HD codecs support higher compression ratios by using more memory, I / O bandwidth, and processors, thereby further increasing the demand for the system.
* Focus on video and audio, because it directly indicates the quality of user experience.
* Reasonably choose the display size. HD is only effective for monitors of 40 inches and above; for smaller monitors, the viewer cannot distinguish the difference between HD and SD. And the compression algorithm will cause loss, so the decompressed image is not as clear as the original image.
* With programmability, allowing the system to be upgraded or redesigned in the future to meet the needs of different regions and markets.
* It is important to keep in mind that the new equipment can be interconnected with the old system. The exchange of video data in home networks is increasingly required to support different data formats.
* Seriously consider the trade-off between effect, bandwidth and cost. If a system-level chip using DSP is used, since it can provide better flexibility, optimized video peripherals and accelerated performance, it can reduce some costs; the processor with integrated DSP and RISC core can achieve the function division; Programming provides better adaptability and upgradeability for the system, and a comprehensive software platform with audio-video API and standard codec algorithms can increase development time.
Should not
* Assume that digital video is the same as HD video. The general public may be a little vague about the difference between HDTV and DTV. In fact, the entire range of digital video applications is too large, and HD is only part of it.
* I think there is only one format. HD contains many display resolutions. This table shows some of the more common DTV formats, but there are others that are still in use. Although most commercial TV broadcasters in North America are implementing 1080i60, other formats may be more suitable for your application.
* Underestimate the complex impact of the market when choosing a processor. All ITU / MPEG standards provide differences in implementation, and from MPEG-2 to H.26 in the next few years? / MPEG-4 AVC codec changes will be obvious. There are other competitive standards, such as WMV9 / VC-1 and AVS in China, which will also retain their application share. Systems such as set-top boxes need to constantly respond to various standards and changes, as well as interface with entertainment and gaming equipment, various format conversions and rate conversions in home computer networks.
* Ignoring system integration is rapidly reducing the cost of HD, so today a system with low performance and price may become higher in the next generation. System developers now have to decide whether to support HD, whether to support HD at a higher cost today, or to maintain SD for another one or two years, that is, after the cost of HD components has fallen or users' demand for HD has risen .
* Let the overwhelming HD ads make the decision for you. HD is not required for all applications. The real question is how to achieve the best possible video quality for the target display under the constraints of system bandwidth, storage capacity, and ubiquitous cost constraints.
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