Over the months we have had many comments about the BBC HD channel on this blog, other chat rooms and directly to the BBC HD team.
Not all of them are negative in fact many of them are very positive.
Whenever I see negative technical comments I do always look at the issues.
Only last week hobwell spotted the 5.1/2.0 switching had stopped some time during the evening. I hadn't watched the stereo programme concerned and I didn't see the comment until 18:30 the following day but I watched the channel start and as I knew the first programme was stereo I was on the phone to the duty engineers in a few minutes. We had the problem fixed, put out an on air apology very quickly and I posted some comments in Danielle's DOG Blog!
(Dolby labs picture from deltamike on flickr)
Other comments on quality do take some investigation.
As a slight change to my usual commentary I wanted to share some of a reply I gave recently to a more general complaint about picture quality on the BBC HD channel.
It also allows me to introduce Rowan de Pomerai, a BBC Research graduate who is working with me for the next few months on a project to improve Dolby E sound on BBC HD.
Rowan has his own blog so you can keep up to date with his project and his thoughts there!
Here is an edited version of the response to the complaint:
"Thank you for your comments about the quality of programmes on the BBC HD Channel...
I want to assure you we do take picture quality very seriously and use a rigorous quality check before any programme delivered on tape is transmitted. Whenever we can we also work with studio and outside broadcast companies to make sure live programmes meet the highest standard too.
You mentioned Amazon was "colour merging". I am not sure what you mean by this but I have not seen anything similar on my home display. I have spotted one other post that compares Amazon to the Sky 1 series "Ross Kemp on..." saying the latter has much higher picture quality.
I have watched both series in HD and must say they are similar in several respects, they both have very good HD content mixed with standard definition material and some sequences that have obviously been shot under very challenging conditions.
I agree some of the low light and night sequences in Amazon are not up to the standard of the majority of the programme.
Programmes like Amazon will always have sequences where conditions mean no matter how good the broadcast technology, domestic cameras that are always much smaller and less conspicuous will be used to reduce risk to the crew with a resulting loss in picture quality.
We are always looking at new technologies that will improve the picture quality in challenging environments but it will take some time before it is uniformly high. In the mean time programmes must limit the amount of standard definition or low quality high definition to 25% of their duration.
Your comment about the Tudors is one I cannot understand or agree with. I still have the series on my PVR and watched quite a bit before writing this. The Tudors is extremely well shot, has very little if any video noise and is beautifully colour balanced.
If this programme looks poor on your television could I ask you to re-check your settings? I would recommend turning the sharpness setting to zero, not to use any of the preset picture modes and to turn off, or reduce to zero all picture enhancement options. I would also recommend turning the contrast setting of your set top box to medium or low before adjusting the brightness and contrast on your display.
If you are looking at some of the chat rooms commenting on the quality of the BBC's HD Channel you will have seen threads discussing our transmission bit rate. The channel's bit rate has remained constant at just over 16Mbs since early last year. I don't often recommend external websites but you might find this one interesting.
I am always watching the channel and do make recommendations to any programme that has variable or substandard sequences to see if we can improve it. All programmes have to meet the technical standards of the channel before they can be transmitted but occasionally even we are caught out by a problem that does not come to light until the actual transmission.
The quality of some several recent programmes has been outstanding. The Goldfrapp Electric Prom was one of the best I've seen, Tess Of The Durbervilles was beautifully shot and from the sections I've seen Little Dorrit should be stunning.
The range of programmes made in high definition will continue to increase over the next few years and we will explore what works and what is just not worth it until high definition is the normal mode of operation.
Many of our high definition programmes use the 25 frame progressive standard (film style). I know some people do not like this and think it degrades the resolution of the picture, while others think it contributes to the quality and style of the programme. This mode does actually have more resolution than the 25 frame interlace standard. Amazon, Silent Witness, Tess, in fact virtually all drama, Natural History and many documentaries use this standard.
Cranford, Silent Witness (right), Tess and other dramas are also using the latest large image format cameras. Theses cameras use a single image sensor that is about the same size as a 16:9 35mm film frame and gives the image a very shallow depth of field. A shallow depth of field will put all but the key subject out of focus and allows a director to use focus as a story telling tool. Again some people think high definition pictures should be pin sharp from the nose of a person in close-up to the trees on the horizon, others find all this visual information distracting and a drama director will use focus to point you to the action they want you to watch.
Here lies another point of confusion; sharpness is not the same as resolution. A picture can be very sharp but contain very little detail. This is especially true in standard definition where electronic sharpening is added in cameras to make the image seem clearer. We do not encourage the use of electronic sharpening in high definition cameras and prefer images to look more natural.
I am currently working on an issue we (and other broadcasters) are having with the Dolby E signal that's used move up to eight channels of audio in the space of two. I have a research graduate from BBC Research working with me, this is very exciting as it is an opportunity not only to deal with problems but to delve deeply into the underlying technology and maybe make improvements that all broadcasters can benefit from. Rowan has his own blog and he will be posting comments on the project when he can - here is the latest.
To finish, there are many comments praising the quality of the HD Channel's quality. I am also aware of the many threads berating the channel's lack of quality, I do read them all and try to address some of the concerns in my blogs and as they come up.
If you would like to read more about BBC Research you can find them here
As I said at the begining of the letter we do take comments seriously and try to address complaints and enquiries. I hope this sparks off a lively debate and look forward to your thoughts on Rowan's work.
Andy Quested is Principal Technologist, HD, BBC FM&T.