We have now chosen the best digital TV standard in the country, the ISDB-T International being fit into the Philippine geography, the lifestyle of TV habits of Filipinos and the future expansion of addressing new markets in advertising and broadcasting. Just last year, the National Telecommunications Commission issued a draft memorandum circular ordering ISDB-T International is the sole digital terrestrial television standard of the Philippines.
With this, next step will be the rules and regulations to be obeyed by everyone, from the broadcasters to the receiving public. Back in early 90’s, the Kapisanan ng mga Brodkasters ng Pilipinas formed the KBP Technical Standards for Television to maintain equal and balanced in broadcasting industry, from basic setup of the NTSC analog TV standard, to field strength intensities being measured to avoid interference.
Just this February of 2011, the NTC formed the Technical Working Group – Implementing Rules and Regulations or the TWG-IRR to formulate all the norms on digital broadcast. The group will discuss, as the name says itself – rules, and guidelines on every aspects in the upcoming DTT broadcast. To give you instincts on what to expect in the formulation of the IRR, we’ve read the harmonization documents presented by Japan’s Digital Broadcast Experts Group or DiBEG about the similarities of standardization of Japan’s digital broadcast system by Association of Radio Industries and Broadcast or ARIB and Brazil’s SBTVD group ABNT.
Firstly, most of the rules being discussed in the IRR are discussed with full of technical jargons and acronyms. The papers are preceded by abbreviations and definition of terms, as well as the scope of the rules. The IRR is subdivided into technical categories, such as transmission, video and audio standards, multiplex, service information, receivers, security, interactive channel or the middleware and data broadcast. Both Japan and Brazil do have the same concept and same flow of the rules being set, so we do expect the NTC to also follow the suit.
What differs into both ruling systems is Japan’s inclusion of digital satellite and cable TV broadcast, since Brazil’s ABNT guidelines only discuss the terrestrial system. In the Philippines, cable and satellite TV migration is not mandatory, so only the DTT will be deliberated further in the regulations.
In the next paragraphs, we will discourse each categories, hypothetically analyze each to suit into the Philippine digital terrestrial TV broadcast.
Transmission
In the document posted by DiBEG, Japan and Brazil uses the same bandwidth of 6 megahertz, the current TV bandwidth being used in analog, as well as the carrier frequency of 143 kHz above the center frequency, sampling frequency and other technical matters. What differs from both is the frequency allocation, where Japan utilizes UHF band only (14-62) and Brazil includes the highband VHF and UHF (7-69) for their digital broadcast. Others as well as the transmission spectrum and spectrum mask.
Philippines, for sure, will also use the current 6-MHz TV bandwidth for every channel, along with the carrier frequency of shifted 143 MHz on the center frequency. About the frequency plan, tentative is to use the current UHF standard of the Philippines as stated in the KBP guidelines of channels 14 to 62, just like Japan.
Video
In this chapter, the video standard was primarily discussed by both ARIB and ABNT’s rules. Technically, it conveys the scanning capability in digital broadcast, the video signal, video formats and resolutions being used in the broadcast. It both also discussed the procedures on switching formats, from SD to HD and vice versa.
ISDB-T, or other digital broadcast standards, also offers multi-broadcasting. Multi-broadcasting in DTV implies switches from SDTV to HDTV and vice versa. Whenever a channel is in Multi-SD format, for a time it will play a movie in HDTV, a broadcaster can easily transform its setup from 3-channel SDTV to 1 HDTV channel. In both ISDB-T variants, this procedure is preferably available in both markets, it’s the broadcaster who will choose whether they like to implement this or not.
Similarities within both standards also being discussed were the active coding areas, scanning direction, video signal parameters and other technical stuffs. 1seg video encoding is also similar to both flavors, since they use the H.264 MPEG-4 AVC video standard.
What differs from both standards are, essentially, the video coding system in full-segment transmission. Brazil chooses to implement the ITU standard for DTV, the use of H.264 MPEG-4 AVC, while Japanese video standard uses H.262 MPEG-2 video. In principle, H.262 video offers lossless video quality, which is perfectly in-stream with the new Blu-Ray video standard, whilst MPEG-4 is also at par with the quality of MPEG-2, but in reality, the latter is a compressed one, giving way much better use of the bandwidth. As much as possible, 1 HD channel on MPEG-2 can carry 2 HD MPEG-4 AVC channels.
Another difference is, Brazil included in its specifications, the seamless switching of picture aspect ratio with the 525i TV system, which is PAL-M. Remember that the Brazil’s PAL-M is much similar compared to the widely-used NTSC-M. Aside from that, the receiving operations are different for both, since SBTVD includes the 14:9 aspect ratios. 1seg video resolutions also differ, as Brazil includes CIF quality (352 x 288) and the 30fps, while Japan only has 15 fps, QVGA video (320 x 240), as the maximum resolution for portable TV broadcast.
Preempting the Philippines’ own rules on digital broadcast, it will be using the SBTVD standard MPEG-4 AVC. Currently, ABS-CBN is the very first digital TV network to transmit MPEG-4 AVC video, since NBN and GEMNET is under the MPEG-2 video standard. With this, ABS-CBN can fit those 7 channels (including the 5 premium channels to be offered soon) into the 6-MHz bandwidth. Aspect ratio is further being discussed in the IRR, as well as the multi-broadcasting feature. 1seg broadcast will also be using the MPEG-4 AVC, in Japanese video format QVGA at 15 fps.
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