Why is RTE on DTV such low resolution?

n97 mini

We were told that mpeg4 was better than what the Brits had, cutting edge and all that, etc, but yet at only 528x576 RTE in SD isn't even full PAL resolution, and visibly slightly poorer picture quality than it is on satellite.

RTE2 HD isn't full HD either at only 1440x1080, and doesn't have the crispness of Channel 4 HD on satellite which is the full 1920x1080.

Why is this? Were we sold a pup, or are they going to up the resolution and improve the picture quality.

The Cush

n97 mini wrote: »

We were told that mpeg4 was better than what the Brits had, cutting edge and all that, etc, but yet at only 528x576 RTE in SD isn't even full PAL resolution, and visibly slightly poorer picture quality than it is on satellite.

RTE2 HD isn't full HD either at only 1440x1080, and doesn't have the crispness of Channel 4 HD on satellite which is the full 1920x1080.

Why is this? Were we sold a pup, or are they going to up the resolution and improve the picture quality.

Saorview SD is 544x576i. According to Watty here "544 x 576 in theory is slightly better than perfect Analogue".

Difficult to compare terrestrial and satellite channels, a terrestrial multiplex doesn't have the same bitrate capacity available to a satellite multiplex.

byte

BBC HD, BBC1 HD and some ITV HD regions are also 1440x1080i (both sat and terr), are they not? It's not an exclusive resolution of RTE.

Kensington

The BBC's have upped their resolution on DSAT recently with the switchover to DVB-S2 on that TP I think?

I'm not sure if RTÉ intend upping the resolution once Mux 2 comes on board - upping resolution would require upping the bandwidth allocation to cope and bandwidth is money.

givecredit

Kensington wrote: »

The BBC's have upped their resolution on DSAT recently with the switchover to DVB-S2 on that TP I think?

.

BBCs on Satellite still 1440x1080.

The upped the res only for duration of 3d tennis in june.

The Cush

Kensington wrote: »

I'm not sure if RTÉ intend upping the resolution once Mux 2 comes on board - upping resolution would require upping the bandwidth allocation to cope and bandwidth is money.

According to the consultation back in Nov it'll be remaining at 1440x1080i.

n97 mini

The Cush wrote: »

Saorview SD is 544x576i.

During the mpeg2 trials it was 720x576. Now it's 528x576 and 544x576 on satellite.

Doesn't explain why with all the mpeg4 hullabaloo etc the picture quality is lowest common denominator rather than being class leading.

The Cush

n97 mini wrote: »

During the mpeg2 trials it was 720x576. Now it's 528x576 and 544x576 on satellite.

Thanks for the pic n97. What DTT receiver are you using?

Can anyone read the data stream to confirm the reduction in resolution?

fat-tony

On DTT, DVBViewer reports 544x576, as it has done all along since MPEG4 started. The 528x576 reported may be some anomaly of the particular receiver.

tlaavtech

My guess is that the 544/528 discrepancy is related to the non-picture scan lines that carry aertel etc. The receiver is listing the genuine lines that make up the picture with DVBViewer showing total transmitted lines.

fat-tony

The first figure (544 or 528) represents the horizontal resolution, so my guess it's some sort of multiple of 16 issue.
The 576 is the vertical resolution (from the analogue 625 line standard) where the aertel, widescreen switching etc would be.

lawhec

tlaavtech wrote: »

My guess is that the 544/528 discrepancy is related to the non-picture scan lines that carry aertel etc. The receiver is listing the genuine lines that make up the picture with DVBViewer showing total transmitted lines.

Not the case as (a) 544/528 refers to horizontal resolution (the number of dots in one horizontal line), and (b) teletext is carried as a separate data stream in a multiplex which is added by the receiver into an analogue output signal - the video stream itself in the multiplex only carries imaging data and unlike analogue, has no "spare" lines.

It's the case that quite a lot of digital transmissions in the UK are below D1 resolution (704/720x576). Ofcom mandate that BBC1, BBC2, ITV1 (or UTV, STV & CTV), Channel 4 and Channel 5 are broadcast in no lower resolution than 704x576. However the majority of the other channels on Freeview have lower resolutions of usually 544x576. The simple reason is that the consequential loss of sharpness is traded off releasing some spare data capacity, somewhere in the region of 20%. It's effect isn't too noticeable on 4:3 transmissions, but can be well seen on 16:9 programmes that have low bitrates - particularly on large (42 inch plus) screens. Coincidently all the ITV1 SD channels on Astra 2D don't broadcast in D1 resolutions except in some temporary circumstances.

The advantages of MPEG4 compression is simply that - it can compress video data better and more efficiently than MPEG2. It has no effect on what screen resolution the broadcaster decides to transmit.

tlaavtech

You mean there is a difference between up/down and left/right

EDIT: I blame the use of two five hundred numbers instead of one nice seven hundred one for my brain fade!!

The Cush

lawhec wrote: »

Not the case as (a) 544/528 refers to horizontal resolution (the number of dots in one horizontal line), and (b) teletext is carried as a separate data stream in a multiplex which is added by the receiver into an analogue output signal - the video stream itself in the multiplex only carries imaging data and unlike analogue, has no "spare" lines.

That was my thinking too but had a look at an RTÉ Multiplex Model from a 2009 tender and it lists Analogue Teletext / Subtitling as Embedded VBI.

lawhec

The Cush wrote: »

That was my thinking too but had a look at an RTÉ Multiplex Model from a 2009 tender and it lists Analogue Teletext / Subtitling as Embedded VBI.

Bit of a strange one as that list also has the main audio as being embedded too! But as far as I know, the VBI only exists in analogue broadcasts.

fat-tony

What they are referring to (I think) is teletext embedded in the VBI by the set top box on the SCART (analogue) connection to the TV. SKY boxes do this. I think most other STBs have their own teletext decoders and perform an overlay on the video signal instead of using VBI, although they could just insert the teletext data into the VBI also.

edit - sorry just read the cush's attachment on the multiplex model. Seems to indicate teletext is carried in the video stream alright, but it's actually carried in a separate stream in the multiplex in reality.

n97 mini

The Cush wrote: »

Thanks for the pic n97. What DTT receiver are you using?

Can anyone read the data stream to confirm the reduction in resolution?

Vu+ Duo.

A mate with the same USB tuner on a DM800 reports the same resolution, although whether or not it's 16 pixels out isn't really the issue, which is why is the picture quality on SD so "average". During the trial it was noticeably better than on satellite as it was 720 wide.

The Cush

n97 mini wrote: »

why is the picture quality on SD so "average". During the trial it was noticeably better than on satellite as it was 720 wide.

Probably because Mux 1 is full, no spare capacity (bit rate) available to increase resolution.

Kensington

fat-tony wrote: »

What they are referring to (I think) is teletext embedded in the VBI by the set top box on the SCART (analogue) connection to the TV. SKY boxes do this. I think most other STBs have their own teletext decoders and perform an overlay on the video signal instead of using VBI, although they could just insert the teletext data into the VBI also.

edit - sorry just read the cush's attachment on the multiplex model. Seems to indicate teletext is carried in the video stream alright, but it's actually carried in a separate stream in the multiplex in reality.

That document refers to how the content is presented to the RTÉ headend gear and presented to the end user display device, not necessarily how it is encoded/broadcast in the Mux transport stream.

VBI doesn't exist in the digital video domain as such - despite it being digital in itself! MPEG encoding deals with pure video images only.

The way Mux1 operates at present, the "teletext" services are encoded into a 300Kbps bitstream on it's own PID. The PID is then grouped under the logical channel (e.g. 1 for RTÉ One, 2 for RTÉ Two HD etc.) alongside the video, main audio, audio description, MHEG streams etc. The STB takes the associated LCN bitstream, where available, and inserts it into the VBI lines over Scart/RF locally.

If you have a TS analyser you can see the Mux structure, including the grouping of EBU teletext under the associated LCN - I'll try and get a screengrab of it up here over the weekend and it should all make sense - that is if I can get my capture card working with Windows 7

fat-tony

That's a re-statement of what I said, with more technical detail. The teletext data (and MHEG data) are grouped with the programme video and audio streams and there have been several postings in the forum showing an analysis of the muxes. I use the transport stream analysis tool provided with DVBviewer Pro to parse the programme streams. The statement about VBI in the digital data streams didn't seem to make sense alright. I had just assumed they meant the mechanism by which the STB might insert teletext data on the SCART / composite video feed to the TV.

copacetic

fat-tony wrote: »

That's a re-statement of what I said, with more technical detail. The teletext data (and MHEG data) are grouped with the programme video and audio streams and there have been several postings in the forum showing an analysis of the muxes. I use the transport stream analysis tool provided with DVBviewer Pro to parse the programme streams. The statement about VBI in the digital data streams didn't seem to make sense alright. I had just assumed they meant the mechanism by which the STB might insert teletext data on the SCART / composite video feed to the TV.

In SDI the term VBI is often still used for the packets of embedded ancillary data as this is where they end up.
http://en.wikipedia.org/wiki/Serial_digital_interface#Ancillary_data

The tender just let's mux providers know that they will be handed a single video cable per service from each broadcaster, with embedded audio, subtitling, audio description, WSS or whatever present. So they need to decode all this as and re-encode it onto the mux as separate streams.

Eg this piece of HW embeds subtitle files, blocking info, WSS, anything you want really:
http://www.axon.tv/EN/products/3-modular-interfacing-and-conversion/49-miscellaneous-video-processing/632-hsi11-hdsd-sdi-vbivanc-encoder-vflex®-powered

Neworder79

RTE1 and in particular studio based programs like Six One News are very fuzzy, blurry and flat for me, it was very bad last week but don't think weather could be causing this? I've a new Samsung LED with built-in digital tuner so would expect TV not at fault, everything else looks fantastic.

Presumably a combination of SD studio input and low bit rate/res being discussed here. Didn't RTE install HD equipment in last news studio upgrade? Seems odd that their flagship news shows look so poor.

But the quality of the upscaled SD from my UK Freesat box is fantastic so it may just and make Saorview SD look worse when you switch. Out of interest do Saorview boxes upscale SD like the Sat boxes?

John mac

Neworder79 wrote: »

RTE1 and in particular studio based programs like Six One News are very fuzzy, blurry and flat for me, it was very bad last week but don't think weather could be causing this? I've a new Samsung LED with built-in digital tuner so would expect TV not at fault, everything else looks fantastic.

?

There is currently No hd on rte1,its not upscaled either,

Rte2 is the hd channel .

n97 mini

John mac wrote: »

There is currently No hd on rte1,its not upscaled either,

He never said it was. He said that RTE installed HD studio cameras.

John mac

n97 mini wrote: »

He never said it was. He said that RTE installed HD studio cameras.

did you read the first line of his post?

Neworder79

I was referring to RTE1 SD content being worse than I'd expect, far less sharp than analogue. As I said some programming looks good on the channel, presumably being downscaled from a better HD original. But their studio shows look particularly blurry and soft.

Rick_

SO, when RTÉ TWO HD moves to MUX 2 on it's own, will the extra space mean all channels can increase resolution to 720x576 and enjoy a bit rate increase as well?

Flicking between SD on RTÉ TWO HD and the other SD channels and it is astounding what a few more lines of resolution and bitrate will do for picture quality, even if the programme isn't in HD. The sooner the entire service goes HD and all channels are at a much higher resolution and bit rate the better. Some of the quality at the moment is just awful.

watty

No. The Extra space is political mandated by BAI to "encourage" other broadcasters to join.

mike65

Eh? The plan is for RTE1/2/TV3/TG4 to be HD when the second MUX comes on line

The Cush

mike65 wrote: »

The plan is for RTE1/2/TV3/TG4 to be HD when the second MUX comes on line

There is no such plan, only RTÉ 2. The 3 other channels will no doubt go HD in due course.

This from the Ministerial decision last Feb

Conditions attaching to Specific Channels

1. RTÉ Two HD Select channel is required to be carried on the second multiplex;
2. The knowledge gained from technical trialling of the HD channel will be shared with other broadcasters;
3. RTÉ should aim to provide for full HD versions of RTÉ One and RTÉ Two as soon as practicable and by mid 2013 at the latest;

lawhec

A mandate should have been made, similar to that for the main terrestrial channels in the UK by Ofcom, that RTÉ1, RTÉ2 (not at this stage needed due to permanent HD broadcast), TV3 & TG4 be broadcast in full D1 resolution (720/704 by 576) if broadcast in SD.

Antenna

Neworder79 wrote: »

RTE1 and in particular studio based programs like Six One News are very fuzzy, blurry and flat for me, it was very bad last week but don't think weather could be causing this? I've a new Samsung LED with built-in digital tuner so would expect TV not at fault, everything else looks fantastic.

Presumably a combination of SD studio input and low bit rate/res being discussed here. Didn't RTE install HD equipment in last news studio upgrade? Seems odd that their flagship news shows look so poor.

But the quality of the upscaled SD from my UK Freesat box is fantastic so it may just and make Saorview SD look worse when you switch. Out of interest do Saorview boxes upscale SD like the Sat boxes?

With RTE, the video being played out is often of poor quality to start with.

News reports often have poor video.

Irish productions are often recorded with poor video resulting in bad motion blur.

That Paddy O'Gorman programme on Sunday evenings I saw a couple of times (I think it is ended now) for example had poor video with bad motion blur (even when the camera was panning slowly).

Their archive video is usually of poor quality (very lossy digitising). I came across some documentary about hurling on TG4 last week - and the picture quality of old 1980s and 1990s footage was horrific (the digital compression used to copy the originals could not properly deal with a fast moving picture). The picture was just a megablur when the camera panned quickly.

mike65

RTE are not the only ones who use shoddy on line video sources it has to be said, re HD for all the main channels, I have to say that's incredible - I've clearly been labouring under a misapprehension.