Dialog TV: Going MPEG-4

NOTE: The switch to MPEG-4 is probably not going to happen so soon, but this article will remain here if anyone want to get a faint idea of what may be planned.

Dialog Satellite Television is planning to add a wide range of new channels within the next few months using MPEG-4 encoding technology. MPEG-4 offers lower bitrates and better quality, which means that any digital broadcaster can broadcast even more channels than before within the same limited space.

Lets have a look at what MPEG-4 can change for current and future customers of Dialog TV.

Solving the Transponder Issue
Dialog has only three transponders at the moment, with one more on its way. Each of the current transponders can fit in around 18 channels (except the third transponder, which has 19) with acceptable quality using MPEG-2 encoding. This results in a total of 55 channels, which is the channel count on Dialog. Once Dialog gets a transponder, addition of channels can be done fast. But the problem is that transponders are expensive, and satellites are fast running out of them.

So the best solution is to fit as many channels as possible to the existing transponders. This can be done even now with MPEG-4. But ultimately each channel will have less bandwidth to call its own, and the overall quality will suffer.

This is where the new MPEG-4 comes in. Using MPEG-4, the current channel number of 18 per transponder can be doubled to 36 channels. Yet there will not be a loss of quality because of the magic of MPEG-4. The quality may even be better than before.

This means that Dialog can avoid having to purchase more transponders, but still introduce more new channels.

Being a MPEG-4 decoder does not mean that the decoder is immediately MPEG-2 compatible. This depends completely on the hardware and software. But since MPEG-4 decoder processors are quite powerful, it is likely that MPEG-2 can also be decoded quite easily after a system software upgrade.

The Current Plans
Please note that these are subject to change. Visit the Dialog TV Forum for the latest information.

Dialog now plans to introduce a fourth transponder with 35 channels, using MPEG-4 encoding. This will surely be a great treat for the customers.

But using MPEG-4 will need customers to purchase new decoders, and so far Dialog does not sound like they will give them out free. According to the current information, those who want access to the new channels can purchase the new decoder. The new MPEG-4 decoder will cost around LKR 6000+++.

The new decoder will be backward compatible with MPEG-2, as channels on the existing three transponders will not be upgraded to MPEG-4 immediately.

Certain sources suggest that Dialog TV will use the same decoder as the Indian DTH service Sun Direct. Sun Direct too broadcasts using MPEG-4, and uses the same Irdeto encryption technology, so this is quite possible.

There is also a possibility that MPEG-4 decoding will be enabled through some sort of software upgrade for existing decoders, but it depends completely on whether the hardware will be powerful enough to decode the power hungry MPEG-4.

Customers will have to watch and wait till Dialog launches their new transponder with new technology. Unfortunately, the new channels being in MPEG-4 means that existing customers cannot watch the test transmissions. Lets be patient, shall we...

MPEG: A Brief Overview

Motion Picture Experts Group, better known as MPEG (pronoounced "M. Peg"), is the group responsible for developing and standardising three of the world's most popular media encoding formats. The MPEG encoding is using in almost all digital broadcasting services, and also in a variety of digital video discs (DVD, HD DVD, Blu-Ray).

MPEG-1
This is the first MPEG standard, whose first version was finalised in 1993. It was developed with the idea of fitting audio and video into a Compact Disc (CD). The format was made the base of the Video CD, a compact disc containing MPEG-1 encoded video which became most popular in Asia.

MPEG-1 allowed for acceptable quality with a resolution only upto 352x288 pixels, and with a maximum bitrate of around 1.5 Mbps. The video quality was similar to that of a VHS tape, except for the pixelation. The audio consisted of only one channel (mono). The standard is almost obsolete today, but is important as it gave way for the more advanced MPEG standards we use today.

MPEG-2
This is the most widely used multimedia encoding standard in the world today, mainly because of its usage on DVDs. MPEG-2 is used worldwide for digital broadcasting as well.

MPEG-2 supports upto 720 × 576 resolution with max. 8 Mbps bitrate for usual DVD-quality video. It also supports High Definition video upto 1080p with a high bitrate. MPEG-2 Audio allows 2 (stereo) or more channels to be included, using MP2 or AC3 encoding.

MPEG-2 has less quality and a much higher bitrate requirement for HD video. Nevertheless, it is popular for broadcasting in High Definition.

MPEG-4
This is the newest MPEG standard available today, and hopes replace its predecessor MPEG-2 very soon. It was finalised in 1998, and first became popular for use in encoding media to share on the internet. Later it was adopted as the standard encoding format for the Blu-ray and HD DVD media discs.

There are substandards which work under MPEG-4, including MPEG-4 AVC, x264, DivX and Xvid. The actual quality and bitrate-efficiency depends on the substandard used. H.264 is arguably the best, with bitrates as low as 3.75 Mbps for HD video.

MPEG-4 is most advantageous over MPEG-2 because it can encode very high quality video with much lower bitrates than before. It also supports High Definition video. Bitrates vary according to the substandard used. A regular DVD-quality video using 8 Mbits in MPEG-2, can use as little as 2 Mbps on MPEG-4 to with hardly any quality loss.

Many DTH services now use MPEG-4 because of its low bandwidth usage. On satellite DTH services, even more channels can be squeezed into a transponder using MPEG-4. This can reduce costs greatly for service providers, as less transponders are required. DirecTV, Dish Network (both in USA), Reliance Big TV and Sun Direct (in India) all use MPEG-4 for broadcasting, and many existing services will upgrade to the new technology within the next few years.

The MPEG-2 standard would become obsolete very soon if DVDs did not exist and/or HD DVDs and Blu-ray discs did not cost so much.

In Sri Lanka - Dialog TV hopes to add new channels using MPEG-4 very soon. I will be covering that subject in another post, coming soon.