Enregistrement magnétique des images : formats numériques

In the "Magnetic recording of images" article , the reader will find all the theoretical aspects and the succession of the main analog VTR formats, followed by what we call the first generation of digital VTRs.

The purpose of this article is to present the professional formats launched by the industry since 1993, which are widely used by production and post-production companies on the one hand, and broadcasters on the other. We will add a few new technologies applied in these devices, insofar as they provide interesting functionalities for the operator.

These recent formats (figure 1 ) are characterized by the recording of component signals and by the systematic use of digital bit-rate reduction, also known as compression, applied in different ways depending on the format.

In 2003, it's safe to say that the formats recently released in standard definition (525 or 625 lines) probably represent the last formats ever produced, since the VCR is gradually giving way in television equipment to video servers, whose introduction in the mid-1990s marked an important stage in the evolution of hardware and operating methods. The main criticism levelled at VTRs concerns the linear access imposed on every sequence on the tape, which can lead to a waiting time of around three minutes when rewinding the tape in its entirety. In post-production and broadcasting, the changeover has already taken place to a large extent; only production is holding out, until a common standard for recording on rewritable discs from the DVD

.

will see the light of day. Of course, this doesn't mean the end of VCR use, because on the one hand, the hundreds of millions of recorded cassettes constitute a heritage that must and will have to be accessed, and on the other hand, certain digital formats are being reborn...