Picture quality problems right at source, not tranmission medium

[dukeofearl]

Just watched the two rugby games on the BBC, using NTL cable through my very old Pioneer 502 Plasma screen - What a difference between them !!

The game from France was only 4:3, with black bars left and right as part of the widescreen BBC source, but the picture quality was superb. Both still frame and fast action was encoded superbly giving an overall great picture.

Then game the Wales/Scotland game. In widescreen this time, the still(ish) frame shots were fine, but as soon as the picture was panning or there was a lot of action in shot, it just turned into a grainy, "boxy" mess !!

Perhaps the BBC need to spend a bit more on the MPEG encoders they use !!

It shows that there is no right answer about the quality of broadcast TV through digital. It's the source that matters - not the transmission medium.

Are your other widescreen pictures OK? Sometimes the box forgets its meant to be in widescreen mode and incorrectly formats the screen. Switching to 4:3 and back to widescreen in the STB menus fixes it.
However it could be that the Beeb were using a compressed feed from the game into their playout centre and the picture quality was indeed impacted by this.

[dukeofearl]

Definitely the source - I'm familiar with the widescreen switching issues. Unlike some modern plasmas, the old Pioneer auto changes according to the source OK.

The BBC often puts it's own black bars on when it has to show 4:3 material from other sources and remains in widescreen mode, though it's own old programs are normally shown in 4:3, letting the user decide what mode to use - Just, Wide or 4:3 etc.
Another well encoded source is the C4 cricket, though I suppose the speed of action is a bit slower

They won't change the encoder for different events, its going to be the quality of the feed arriving to be encoded that makes the difference. A full bandwidth uncompressed digital feed of 270Mb/s is expensive so in most cases there will be compression before the feed gets to the encoder site.

[dukeofearl]

Shame they got a better feed from the French (apart from the 4:3) than they got from their own cameras in Wales - I await the England game with interest to see what the Italians can supply.......

[magpie]

The black bars down the sides of the picture for the France game cannot require too much data to produce (no motion, no edges, only one colour). This would allow much more of the MPEG stream to act on the actual picture, increasing its quality.

Assuming that the bitrate of the channel remained the same for both games, this would give a higher quality (albeit smaller) picture for the france game.

IF this is true, then it cannot be said that the picture quality problems are from the source. It is more likely to be a run of the mill bitrate problem.

I'm just taking an educated guess here though - anyone know if it could be right?

Originally Posted by magpie

The black bars down the sides of the picture for the France game cannot require too much data to produce (no motion, no edges, only one colour). This would allow much more of the MPEG stream to act on the actual picture, increasing its quality.

Assuming that the bitrate of the channel remained the same for both games, this would give a higher quality (albeit smaller) picture for the france game.

IF this is true, then it cannot be said that the picture quality problems are from the source. It is more likely to be a run of the mill bitrate problem.

I'm just taking an educated guess here though - anyone know if it could be right?

They dont need to waste bandwidth tho encoding the black areas.
Theres no more actual data in a widescreen picture, theres still 720 by 576 pixels for the encoder to work on.

[paulyoung666]

Originally Posted by dukeofearl

Shame they got a better feed from the French (apart from the 4:3) than they got from their own cameras in Wales - I await the England game with interest to see what the Italians can supply.......

just to point out , watching the england game on sky digi and the picture quality is crap to say the least , very grainy and grotty , but at least england are stuffing the italians