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Listed below are comments made by tagmclaren between Friday, 20th November 2009 and Thursday, 26th November 2009.

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Points of View and HD Picture Quality: a response 08:49am on 26 Nov 2009 Yep,

I can confirm lots of blocking on the cement mixer scene.

Stills don't convey how obvious the problem is, again not with you nose pressed against the screen but from 10/11 feet away.
Points of View and HD Picture Quality: a response 08:50am on 25 Nov 2009 see posts 26 and 27
Points of View and HD Picture Quality: a response 08:48am on 25 Nov 2009 Andy,

Thank you for your response and I look forward to your blog.

Will it provide your reasons for using 9.7 Mbit/s when the EBU expert assessment clearly recommends using 12.1 Mb/s minimum?

Also, whatever your assessment of the picture quality with the new encoders, will your blog explain why I am seeing far more incidences of blocking and other compression artefacts and of course when are we going to be rid of the the fickering pixelation effect in rapid scene transitions and some other more static shots.

BTW I am not the only one seeing this effect:-

http://www.digitalspy.co.uk/forums/showthread.php?p=36897646#post36897646
Points of View and HD Picture Quality: a response 9:00pm on 24 Nov 2009 EBU documents are quite interesting:-

http://www.ebu.ch/en/hr_training/training/technology/pastactivities/2009reports/01_pts.php
http://www.ebu.ch/CMSimages/en/EBU-ProdTech-2009SeminarReport-FINAL_tcm6-64756.pdf

The H.264 (MPEG-4 AVC) encoders used for evaluations, during two experts viewing sessions, were: Ateme Kyrion (status Q3/07), Harmonic Electra 7000 (status Q3/07), Scientific Atlanta D9054 (status Q3/07), Tandberg EN8090 (status Q3/07, and status Q2/08 optimised), GVG/Thomson Vibes EM3000 (status end Q4/08). The state-of-the-art HD MPEG-2 encoder Sciatl D9050 was used as an anchor and reference. Three different tests were undertaken, with the following results

Bit-rates H.264 performs up to/about 50% better than MPEG-2 and even better for certain sequences. Some experts felt strongly that even with the best encoder that 8 Mbit/s (1920x1080i / 25) is insufficient for HD broadcast of critical material. All experts felt strongly that with the best encoder, 6Mbit/s (1280x720p / 50) is insufficient for HDTV broadcast. Recommended minimum bit-rates “for critical material but not unduly so”:
 10,5 Mbit/s minimum CBR for 1280 x 720p/50
 12,1 Mbit/s minimum CBR for 1440 x 1080i/25
 12,8 Mbit/s minimum CBR for 1920 x 1080i/25(MPEG-2 24 Mbit/s reference)

Quality of the encoders has reached a mature level for various vendors and less drastic improvements in terms of picture quality are expected in the future
Points of View and HD Picture Quality: a response 09:51am on 24 Nov 2009 Thanks Paul for your efforts.

What are the timescales on a response? 6 months?

So, will we get silence from the BBC on this until a verdict is given?

Or Andy, ay are you still going ahead with your report on the new encoders?
Points of View and HD Picture Quality: a response 09:47am on 23 Nov 2009 Further to my post 268 about Jools Holland, here are some pics of the blocking.

The pictures don't convey it very well, but with the sweeping lighting changes problems with blocking and compression artefacts wer plainly obvious from a normal viewing distance. The backgrounds had the look of an over compressed JPEG, with noise, sort of mosquito noise and "transparent worms" effect - must be a better term! :)

Similar things can be seen on other programs, CIN, SCD etc.

These encoders clearly cannot cope with demanding material. This sort of problem was not as evident with the old.

http://picasaweb.google.co.uk/lh/photo/veLhowRve7fz6iBRnsBl2g?feat=directlink

http://picasaweb.google.co.uk/lh/photo/F83PXISL5FPlHIn5ybm4xA?feat=directlink

http://picasaweb.google.co.uk/lh/photo/wbvQ34_7ymoLWMjS_Bggqg?feat=directlink

http://picasaweb.google.co.uk/lh/photo/t1R4a5mFzFsYLr0FBXzOGw?feat=directlink

Again, I don't care about bitrate, just stop telling me the PQ is better and please fix the problem.
Points of View and HD Picture Quality: a response 3:32pm on 22 Nov 2009 Just been watching Jools Holland form the 13th.

Joss Stone about 45 mins in showed exactly how these new encoders are failing.

Behind her were sweeping lighting changes. This background was riddled with compression artifacts and blocking. Appalling.

I will post up an off scren photo later.
Points of View and HD Picture Quality: a response 10:13pm on 20 Nov 2009 trevor-245

I thought that the encoders recognised progressive material from interlaced and treated it accordingly. Afterall it's only got to weave the two fields together to get the full progressive frame.

What I am saying is I didn't think that encoding progressive sources was a problem even though they are broadcast interlaced???????....Andy????

I think this may have more to do with variable quality of the de-interlacers in TVs. Presenting them with a proper prog signal may result in a better picture than letting them deinterlace.

Andy comments?
Points of View and HD Picture Quality: a response 10:11am on 20 Nov 2009 RWG

The average birate is not the issue. It's the peak bitrate that is important.

Less complex pictures with less movement(actually change is a better term) require less bits. One reason why mixes suffer is the whole picture is changing.

Sky have the advantage that they have multiple channels on a transponder and can statistically multiplex.

The full data capacity of the transponder is shared amongst all the channels. They are all analysed frame by frame (field by field?) and the most data is given to the channel that needs it the most.

Hence, if required 15Mbs or more can be given to a demanding picture.

A static picture may be perfectly acceptable at 5Mbs.

So unless all the channels have demanding pictures all at once, the cahnces are that most of the channels most of the time will have improved quality.
Points of View and HD Picture Quality: a response 09:09am on 20 Nov 2009 rwgladwin-228

A fair and objective assessment.

For info bitrates can be found here

http://www.linowsat.de/0282/all/0282.shtml

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