Mpeg - Killing Quality.

Watching ITV the other night, it struck me just how bad Mpeg2 encoding is, at least at the bandwidth offered by Telewest. It should surely at least match the analogue signal; but it doesn't - the analogue signal is far better.

But is this ever going to improve? Is the mpeg2 decoding part of the hardware of the set-top boxes or can it be upgraded to mpeg4? Are we stuck with mpeg2 forever? And what about increased resolutions - are we stuck with an increasingly poor-looking 720x576 image forever? Whatever happened to HDTV?!

MPEG2 doesn't have to be bad; I've watched DVDs that look pretty good, certainly a lot better than digital TV. It's all to do with the bandwidths used.

I'm a bit out of my depth here but I suspect that in all DTV boxes (cable, sky, & freeview) the MPEG2 decoding is done by a dedicated DSP and not the box's processor. This certainly seems to be the case with my NTL box as the UI can completely crash but the TV picture & sound carries on. Therefore it seems highly unlikely they can upgrade boxes to decode MPEG4 "over the air".

So if a switch to MPEG4 is ever made it'll mean new hardware. The best we can hope for is for them to increase the bandwidth used for each channel. The downside for the operators is that they get less channels per multiplex, therefore less value for money. So in other words forget it!

I believe that when the analogue signals are switched off another multiplex or perhaps two will be made available and this extra bandwidth will be used to improve the quality of the 5 terrestrial channels and provide extra services if there's room.

Doesnt Digital cable re-encode the DTT signal,causing poorer pictures

TW is very bad, especially on archive shows like TOTP2. Watching it through the aerial looks 100% better than the digital mush TW gives out

I don't know to be honest, but with NTL the picture quality of ITV1 is very good and I can't really complain, but it's the quality of E4 which is awful, we all know its pixelated when it's in 4:3 Letterbox mode, but when it broadcasts in 4:3 and showing old programmes you can see crappyness of the picture, but I don't know what method they use, obviously 16QAM or 64QAM as I am told. (Or is this DTT only?)

the mpeg2 decoding part of the hardware of the set-top boxes or can it be upgraded to mpeg4?

MPEG-4 is not intended for use in digital TV broadcasting. Its main application is to provide comparatively high audio/video quality at a very low data rate for use in streaming applications, e.g. sending video clips via your mobile phone.

Are we stuck with mpeg2 forever? And what about increased resolutions - are we stuck with an increasingly poor-looking 720x576 image forever? Whatever happened to HDTV?!

There's nothing inherently wrong with MPEG-2 - the problem is that UK broadcasters chose to maximise quantity over quality. If they transmitted fewer channels, and maxed out the bitrates, digital TV would look at least as good as analogue TV, and in many cases it would look better.

HDTV is alive and well in America, Japan and a number of other countries. It will also be available in the UK via the Euro1080 satellite service next year - check out this site for more details. You'll need to buy a special decoder box to receive it, and if you want to see it in full HD resolution you'll obviously need an HD-capable display.

FWIW, HDTV utilises MPEG-2. MPEG-2's maximum supported resolution is 1920 x 1152 (which actually exceeds the HDTV maximum of 1920 x 1080), whereas MPEG-4's is 720 x 576.

it's the quality of E4 which is awful, we all know its pixelated when it's in 4:3 Letterbox mode, but when it broadcasts in 4:3 and showing old programmes you can see crappyness of the picture, but I don't know what method they use, obviously 16QAM or 64QAM as I am told

16QAM and 64QAM aren't really anything to do with the resolution of the picture - they relate to the way the signal gets from the DTT transmitter to your aerial. As with digital TV generally, the question of whether you get a detailed picture or a grotty pixellated one is down to the way the video is encoded, and that's dependent on how the broadcaster has chosen to allocate bandwidth.

Sorry, but that statement is massively inaccurate. Whilst MPEG-4 is only currently used for streaming internet video, it is fully intended to be the sucessor for MPEG-2. Indeed, Apple, one of its primary adopters, has stated that it is suitable for anything from "video phones to digital television".




Yes, but at any set bitrate, MPEG-4 outperforms MPEG-2, both in terms of audio and video. Especially as AAC (dolby digital) is the native audio codec for MPEG-4, as opposed to MPEG 2.1 audio for MPEG-2 transmission.




Actually, MPEG-4 fully supports HDTV, with the Euro-1080 HDTV channel currently testing it.

'Scuse my ignorance but is this really only a problem on DTT and cable? I have Sky digital and, apart from last weekend when the weather was terrible, I've had no problems with any channels - either with pixellation or poor picture quality.

Has Sky simply got so much bandwith that the problem doesn't arise or am I just not demanding enough in my picture quality?

I think SKY picture quality is just as bad in some cases, even with a high signal. Especially the colour red becomes jagged and horrible.

I think sky, and indeed any digital service, initially appears to have 'perfect' picture quality because it is so refreshing for people to see ghost and analogue-noise free pictures. However, after some time, most begin to increasingly notice other picture defects arising from both heavy compression, imperfect encoding and bad reception. These range from actual picture breakup/dropout in bad reception/weather conditions or simply general pixellation arising from heavy compression.

I'm afraid it's the latter. I've never seen a Telewest picture but Sky is definately far worse than my NTL box or any Freeview picture I've seen.