We were talking with Edson Siquara de Souza about the most critical aspects that arise in the management of a contribution system, taking into account the special characteristics involved in the transition stage from an analog system to a digital one in which this important Brazilian television network is located, considered one of the most important in the world and, of course, in Latin America.
TVyVideo: What are your signal transport needs?
Edson Siquara de Souza: TV Globo has different ways of making transmissions and receptions of signals. For example, we can receive at the same time 20 satellite signals (we have 12 antennas pointed for various satellites), 16 fiber optic and 6 microwave. We are also using streaming video and audio over the Internet using MPEG4 or MPEG2. For transmission, we also have fibers and microwaves, and we can transmit by satellite using a fixed digital uplink (MPEG2) at our station in Rio de Janeiro for the NSS806. We also have a space segment in Nahuelsat 1 (Ku Band), permanent, for contribution, using fixed uplinks in São Paulo and Brasilia, as well as SNG in Rio de Janeiro and São Paulo. We also frequently use Embratel's microwave network, which is a national network, interconnecting our 113 affiliates. We also have available a C-band SNG unit, used mainly for sports broadcasts. In addition, we hire several services from other national and international companies.
TVyV: What kind of problems do you have when trying to integrate sources from different sources?
ESS: We are in the process of moving towards a completely digital platform, something that is happening with practically all broadcast companies around the world, with different implementation speeds. In Brazil we are close to having a decision on the standard that we are going to use for digital TV on the air (the ATSC, DVB and ISDB options are being analyzed). Likewise, TV Globo decided to make several changes in various technical areas, many of them already working in digital (but not in high definition). This is a very complex process, where in many cases we have to work with analog content. The biggest problems we have today are related to the reception of compressed video signals, usually MPEG2, since not all encoders on the market are compatible, and there are many that use very old versions, mainly in South America, where MPEG1 or analog transmissions are used in several countries. In recent years, TV Globo has invested heavily in its external production and transmission units, of very good quality. We would be quite happy if we could find redundant digital production or SNG vehicles, with quality compression systems for rent in all South American countries.
TVyV: Are there problems of excessive deterioration of the material due to the number of cascade compression steps to which it must be subjected?
ESS: Yes, when using MPEG2 4:2:0 compression you already see an image degradation in the first cascade. We are trying to work more and more with MPEG2 4:2:2, which presents good quality even after 5 or 6 compression cascades.
In many cases we can perceive a degradation only after the eighth cascade. Another type of solution we are using is to avoid cascades completely, even if we have to use 2 or 3 satellites, using the resource of using only de-modulator and modulator in the turnaround.
TVyV: Does changing systems – PAL/NTSC – represent a real problem?
ESS: No more, in 1998 TV Globo bought two standard conversion units, which have motion compensation, especially for the World Cup broadcasts that year. More recently we have bought another, to be able to convert from NTSC to PAL novels and shows that we sell for other countries.
TVyV: What kind of solution do you have for this?
ESS: In addition to using the resources we have in TV Globo to convert standards, we are looking for companies that have equipment of similar quality that can provide us with services in sports events, journalistic events, among others.
TVyV: Are there audio/video sync loss issues?
ESS: Yes, this is a constant problem, both with standard conversion systems and with compression systems. We have to be quite vigilant in relation to this, as we work with various signals from different backgrounds all the time. Some do not need the use of an audio delay and others demand a lot of correction, since, for example, a standards converter delays the video on average by five frames. For all the signal we receive, we have an audio processor that takes care of that. There are also cases when the video is ahead of the audio, a much more difficult problem to be solved.
TVyV: What platform did you adopt to handle your signal reception/redistribution system?
ESS: As I had already mentioned, Rede Globo and its affiliates are mostly analog stations, each with its agenda for the shift to digital. Our main distribution (signal for the whole country) is still an analog uplink in Rio de Janeiro. Some stations already have digital redistribution using MPEG2, for the signal we call state (because it has state coverage, destined for affiliates that are in the same state as the main station), as is the case of São Paulo and Minas Gerais. Other TV Globo affiliates already have the same type of platform and others will join in the coming years with the same technology. With regard to contribution signals, both national and international, we always try to receive in MPEG2, mostly even in MPEG 4:2:0, but with a strong tendency towards MPEG2 4:2:2.
TVyV: What advantages of this platform did you take into account?
ESS: MPEG2 is a definitive standard that will surely be maintained for several years, which means it is a safe investment. There are equipment from several different manufacturers, for all types of application. DTV/HDTV uses MPEG2/DVB as the compression standard in any solution, be it ATSC, DVB or ISDB.
TVyV: Any recommendations for those facing such a project?
ESS: It is important to start the studies for the change from analog to digital as early as possible, it is a very expensive process and of great technical complexity. But the most important thing is to try to justify the business plan for the shift to digital and high definition with a positive cash flow in a period acceptable to the company. Here at TV Globo we have already been working on this for several years, we are aware that it is a process without turning back, and that the way is high definition with added services. Don't think about leaving it for the last hour.