A family of MPEG formats. Part One: MPEG-1
The history of the MPEG family of formats, to which the rapidly gaining popularity MPEG-4 belongs, began in 1988.
It was in this year that the committee of the Group of Experts on Moving Pictures was founded, which roughly translates into Russian as the Expert Group on Cinematography (Moving Pictures), the abbreviation of which is MPEG is now known to anyone who deals with multimedia: computers or digital. TV. In the same year, development of the MPEG-1 format began, which was finally released in 1993. Despite all the obvious shortcomings of this format, MPEG-1 remains one of the most widespread video compression formats.
I must say that almost all the innovative developments at that time that formed the basis of the MPEG-1 format, in one way or another, are in more advanced formats of this series, therefore, having considered in detail the first representative of this family. of video compression formats, you can get a general idea of how MPEG algorithms work.
MPEG-1 format. Old, but not yet defeated.
The MPEG-1 format began to develop in those hard-to-imagine times when high-volume media was not widely available, while video data, even compressed, was occupying absolutely colossal volumes by the late 1980s, the average length of a la movie was over a gigabyte. If anyone does not remember, then it was the era of the 286 and 386 processors, 4 MB of RAM and a 250 MB hard disk were considered a luxury, not a misery, since now Windows was a gadget for DOS, and not the reverse. and SONY’s newly released 5 “floppy disks and 3.5” floppy disks dominated as easily portable media. In such conditions, it was necessary to find a means
And such a medium was found. Just in those years, for the first time on the PC platform, a new type of storage medium appeared, such as CD-ROM discs, which could provide the necessary amount of information. It is true that a movie in MPEG-1 format did not fit on a disc, but what prevented it from being recorded on 2 CDs, especially since the novelty was very cheap? Of course, the first CD-ROM players were single speed, so it should come as no surprise that the maximum bit stream rate in MPEG-1 format is limited to 150 Kb / s, which corresponds to a CD speed. -ROM.
I must say that the possibilities of MPEG-1 are not limited to the low resolution that everyone saw when watching VIDEO-CD. The format itself allowed the compression and playback of video information with a resolution of up to 4095×4095 and a frame rate of up to 60 Hz. But due to the fact that the data transfer stream was limited to 150 Kb / s, it is i.e. the so-called restricted parameter bitstream (CPB) – the fixed width of the data transfer stream, the developers of the format and later the creators of codecs based on it were forced to use optimized frame resolutions for the given CPB. The most widely used are two of these optimized formats: the SIF 352×240 format,
Well, we have already decided the resolution, now you can see how everything is compressed.
