High definition video
A digital image is the result of a mathematical calculation, in which the number of pixels appears as one of the main parameters, which determines the spatial resolution. Each pixel is assigned a certain value of the luminance signal and the chrominance signals at a given bit depth – the number of bits. The higher the resolution and the more color gradations and brightness levels, the higher the image quality (and, of course, the greater the amount of digital information). When receiving high definition images, all the video information in the camera head is processed and output in the form of HD or HDV video signals, just like a conventional camcorder.
While PAL cameras typically record a signal captured by conventional interlaced scanning, HD cameras offer a choice between interlaced and progressive recording formats. The choice of recording format has a significant impact on the resulting image quality. In interlaced mode, the camera generally works with a vertical filter that can reduce vertical resolution by up to 30%. However, filtering is necessary, otherwise when using equipment in cathode ray tubes, it would be impossible to get rid of the annoying jitter of the image lines. When recording in progressive mode, this problem does not arise and the filter is no longer necessary. Similarly, progressive recording provides better motion resolution because all lines are recorded at once. (See FRAME RATE). Therefore, progressive recordings are much sharper than interlaced images for the same number of lines.
By their own principle of operation, all new display systems, such as plasma and liquid crystal displays (TFTs) and projectors, are progressive. When an interlaced signal is sent to them, the latter must first “break free” from the interlaced structure (“deinterlace”), which is very difficult, requires additional processing, and does not always lead to success. On the other hand, progressive signals are directly reproduced by such screens and deinterlacing becomes unnecessary. Therefore, progressive formats can be expected to prevail in the near future.
DATA TRANSFER RATE (BIT RATE)
The data transfer rate, or the value of the digital stream, or the bit rate is a parameter that determines the amount of visual and audio information transmitted per unit of time. With the same type of compression, a higher bit rate will provide a higher quality signal. When using different compression schemes, the quality will be determined by both the bit rate and the efficiency of the compression. For example, the same bit rate in an MPEG-2 signal provides higher quality than a DV signal because MPEG-2 is more efficient.
COMPRESSION (COMPRESSION)
The video data compression procedure is the condensation (merging) of similar pixels located within the same or adjacent frames in adjacent frames. Similar visual structures in different frames are highlighted by analysis and condensed within a certain number of frames, or so it is called. “Group of Pictures” GOP (Group of Pictures). When audio signals are compressed, “inaudible” information is simply removed from them.
MPEG- the general name of the technological platform created by the International Organization for Standardization ISO (International Organization for Standardization) and the International Electrotechnical Commission IEC (International Electrotechnical Commission). The latter has developed a series of standards for encoding original video and audio signals, which are collectively called MPEG standards. The term MPEG itself is an abbreviation for Motion Pictures Experts Group, which means “Motion Picture Experts Group”. The MPEG group is dedicated to the standardization of digital video and audio compression technologies. The MPEG standards are formed on the basis of a common basic structure that allows a fairly great freedom of configuration and has several levels. Each level describes certain characteristics,
The MPEG2 standard encompasses the technologies found in any DVD player, no matter where it works, and in all digital television systems. HDTV platforms use MPEG2 video compression in MP @ HL (High Level Main Profile) at the following bit rates: 15 Mbps at 720p50 and 19 Mbps at 1080i25. signals are easier to compress, 720p50 with the same image quality is performed at a lower bit rate. For this reason, the European Broadcasting Union (EBU) proposed to use 720p50 as the broadcast format in Europe (see EBU section).
