HD-format

[vbhere]

What is the FCC definition of HD?

I understand the video needs to be at 720p or higher.

Would that mean both 720i (360px2) and 1080i(540px2) is not HD?

Also in its definition, does the 720p resolution need to be at 24fps or higher or is that not mentioned in FCC's HD defintion?

[trapehzoid]

what does it matter? You aren't actually getting HD quality from compressed video systems. What you are really getting compared to other systems is higher resolution.. so its the resolution formats supported by the systems and what output formats they use (for compatibility with displays) that are the real important factors.

If you want to split hairs on terminology (which everyone abuses anyways) go read up on it in Google.. any number of hits for you (and the FCC doesn't define HD..)

http://en.wikipedia.org/wiki/Advanced_Television_Systems_Committee

[vbhere]

what does it matter? You aren't actually getting HD quality from compressed video systems. What you are really getting compared to other systems is higher resolution.. so its the resolution formats supported by the systems and what output formats they use (for compatibility with displays) that are the real important factors.

If you want to split hairs on terminology (which everyone abuses anyways) go read up on it in Google.. any number of hits for you (and the FCC doesn't define HD..)

http://en.wikipedia.org/wiki/Advanced_Television_Systems_Committee


So you're saying that 720p HD-video conferencing at 15fps or 30fps or 7fps for that matter really doesn't matter to you, once a certain resolution is supported.

[trapehzoid]

So you're saying that 720p HD-video conferencing at 15fps or 30fps or 7fps for that matter really doesn't matter to you, once a certain resolution is supported.

The point is even a system that claims 30fps IS NOT 30fps all the time, nor does it even have to be able to achieve 30fps at all. That is what the system claims it can DECODE. What is encoded is anything UP TO 30fps.. and can swing wildly depending on the content. Having a system drop to 20fps or less isn't uncommon at all with motion even without HD.

Plus.. you are dealing with motion based compensation.. so while your image may have 1280x720 lines of resolution, the actual image you are getting is usually less then that because of factors which allow you to update sections with blocks of lower resolution. This is the 'blocky' video you see.. the image resolution being displayed from your system doesn't change.. but the resulting image seen is not the same quality as the original.

We are dealing with LOSSY real-time compression.. which means the image quality can (and does) vary greatly with the content being shown.

This is not unique to HD at all. Play with any system today.. compare the image quality between when you sit still.. and when you move the camera. The system has to drop framerate and image quality to update at least some of the image rather then freezing the entire screen.

So my point is.. what technically describes HDTV in terms of framerates and resolutions is pointless to VTC (ignore the stupid marketers) because what you are using in VTC's real-time world is not the same image quality nor constant framerate like you get in a HDTV broadcast.

All that is important is the higher resolution capabilities and being able to deliver them with a good framerate in the conditions you use it. If its the same as HDTV ATSC broadcasts or not is moot.

A system that can do 30fps 720p for a conference room camera you may say 'its HDTV quality!' but if that system can only do 5fps when doing full motion video such as from a DVD source.. well then that same 30fps 720p system isn't going to give you HDTV quality now is it?

[Yukikaze]

So you're saying that 720p HD-video conferencing at 15fps or 30fps or 7fps for that matter really doesn't matter to you, once a certain resolution is supported.

He is saying that, at a given bandwidth, transmitted resolution, framerate and the quality of an individual image(optical resolution) are all conflicting aspects of video quality that compete for the same limited pool of bits.

If you actually need to compress your video stream increasing one aspect will decrease another. A stable 30fps will likely mean sucky image quality and an optical resolution well below the transmitted 720p resolution when there's movement .

To take an extreme example. A valid compressed representation of *any* input is an output that is a square box of grey color. If said grey box is transmitted at 720p and 30fps, would you still call it video? HD? Useful?

Probably not.

[Sean Lessman]

To take an extreme example. A valid compressed representation of *any* input is an output that is a square box of grey color. If said grey box is transmitted at 720p and 30fps, would you still call it video? HD? Useful?

Good point and well said.

Sean

[vbhere]

Thank you all for your responses.

So at the end of the day, it is more a function of a codecs ability to maintain a high fps at different (quantifyable) amounts of motion.

Which manufacturer is able to maintain the highest frame rate with a lot of motion; Tandberg, P
olycom, LifeSize?

[trapehzoid]

Thank you all for your responses.

So at the end of the day, it is more a function of a codecs ability to maintain a high fps at different (quantifyable) amounts of motion.

No.. you are still missing it. Frame rate alone means NOTHING. Resolution alone means NOTHING.

What is important is how the system balences both to achieve the best possible resulting video.

If you have a picture, moving around alot, the codec can simply drop the picture quality (without changing resolution) to maintain high frame rate. But if the quality degrades so much that you can't make out detail or becomes so distorted.. that high frame rate is useless for you.

On the other end of the spectrum, if you totally sacrafice frame rate for image quality.. your picture becomes very unnatural and becomes very distracting to use.

So what is important is the RESULTING picture. Resolution and Frame Rate are only BOUNDRIES within the system operates. It does not define the resulting picture quality at all in real world use.

A frame in a video call at 720 lines is NOT the same as a 720 line still picture. The insanely high compression ratios achievable in this technology is purely from throwing information away. Even when updating the entire picture, the image quality is lower then the steady-state picture because the only way to get a full update in a short amount of time is to lower the image quality. This is why your video 'pulsates' when they get a full-screen update. The picture updates with a lower quality image, and the detail and sharpness is added in with later updates - all the entire time without changing the resolution the system has negotiated.

[vbhere]

If you have a picture, moving around alot, the codec can simply drop the picture quality (without changing resolution) to maintain high frame rate. But if the quality degrades so much that you can't make out detail or becomes so distorted.. that high frame rate is useless for you.

On the other end of the spectrum, if you totally sacrafice frame rate for image quality.. your picture becomes very unnatural and becomes very distracting to use.

Thank you Trapehzoid!!

So in droping picture quality.....what exactly is being lost....i.e. what is being removed from the image to reduce its quality?

[trapehzoid]

what is being lost? image detail. The system simply 'simplifies' an area of the screen to represent it with less information and is selective in what it actually updates. Framerate is simply how often information is updated.

Unlike a movie or tape.. the entire picture is not updated every frame. Another portion of compression is to simply not update things that don't change. If only 10% of the picture changes from frame to frame, the system does not send the entire picture.. it only attempts to update that 10% that changed. They also use motion based compensation to further increase compression by not sending the picture itself, but rather just send a vector to say 'move this block this way'.

On top of that.. this entire process is dynamic. A system may send 15frames in one second.. and 2 in the next second.

There are plenty of books on this topic and plenty of stuff on the web. even wikipedia has a start point

http://en.wikipedia.org/wiki/Video_compression

[Jontracey]

There is a lot of FUD (Fear Uncertanty and Doubt) being thrown around in the HD arena by sales reps from some companies.

Frame Rates not being important is one of the most silly things I have heard in a long time. Agreed encoders done always change entire frames so rates do vary but maintaining a high percieved frame rate is important so if one system can maintain a percieved 30fps and one can maintain a percieved 15fps guess which will look better.

So my suggestion is ask your local sales reps for a demonstration of any systems that proport to be HD, then see for yourself which you like and best suits your needs. Invite them to do a "Pepsi challenge" and compare them against each other. Do everything you can to reduce the external influences (same screens, same speakers etc) and compare apples with apples.

HDTV,HD,HD Ready,Optimal and others are all marketing terms on spec sheets, look at your business application and choose the best system to suit those needs and your budgets.

Jon

[Sean Lessman]

There is a lot of FUD (Fear Uncertanty and Doubt) being thrown around in the HD arena by sales reps from some companies.

Jon, I hope you are not implying that LifeSize salespeople are so ethical that FUD is below them. I think we all know sales people will say what sales people will say regardless of what company they work for.

Frame Rates not being important...

I dont think frame rates are important. I think the experience is. How many people outside of our industry know the TV they are watching is 29.97 frames per second? They don't care. They do care that the football game they are watching looks good.

Invite them to do a "Pepsi challenge"

Every video system can be made to look bad as they are all biased towards certain operating points (speeds, lighting, resolutions etc). Even your product can be made to look bad. There are teams of people in some of the industry's companies that spend their time trying to find the situation where the competition looks bad for just this reason. Pepsi challenges are typically fixed competitions. I would encourage testing any solution in your environment as you would use it every day.

HDTV,HD,HD Ready,Optimal and others are all marketing terms on spec sheets

Isn't is all *really* marketing right now? Isn't saying HD and ease of use (sound familiar?) go hand in hand, a big mouthful of marketing? The optimal definition story from TANDBERG has little to do with 'HD' and more to do with the ability to provide the right resolution for the application you are using at any given time. Its about having the flexibility to connect to *anything* not just ourselves.

...look at your business application and choose the best system to suit those needs and your budgets.

Agreed. However the 'cost' point you make isn't as simple as the cheapest endpoint. Building a solution out of mixed parts usually ends up costing more over the life of the application as you spend countless hours being stuck between vendors trying to install the stuff and solve your problems. We used to be a codec only company too...but the times have changed and our customers demanded more.

I think Trapezoid has some very valid *down to earth* points.

Sean

[trapehzoid]

Frame Rates not being important is one of the most silly things I have heard in a long time.

No, frame rate being everything is the most silly thing I've heard in a long time. The fact is these stupid vendors want to compare spec sheets all day long and boast about 'my point is bigger then their point' rather then just making this stuff work great. Stop focusing on your sales pitch and start using success stories as examples. When your neighbor 'saves the day' using VTC.. thats when peer influence takes off.. and so will your sales. Did skype every sit down and pitch to everyone that their quality is 2.6 time better then everyone else? No, they just freaking did it and the money flowed. Maybe the vtc vendors will wake up someday, realize they have good stuff, and stop dreaming up sales pitches and start dreaming up success paths.

Agreed encoders done always change entire frames so rates do vary but maintaining a high percieved frame rate is important so if one system can maintain a percieved 30fps and one can maintain a percieved 15fps guess which will look better.

another useless statement. Framerate alone means nothing. If I drop the picture to a useless blob, but one that updates 30 times a second, do you feel good about it? Do you go home at night with a smile thinking 'man.. my frame counter looked awesome today!'?

HDTV,HD,HD Ready,Optimal and others are all marketing terms on spec sheets, look at your business application and choose the best system to suit those needs and your budgets.

Jon

Even better.. don't even look at the spec sheets and just test drive everything you can. Put the system through the paces you want to use it as and put the person who is going to be using it in the drivers seat. Demos are generally pointless because they are so contrived.

[trapehzoid]

I think Trapezoid has some very valid *down to earth* points.

Sean

Cool.. I like staying planted on the ground. but I thought we were from mars? or at least thats what the girl keeps saying :)

[jerry@jonesgroup.net]

High definition video -- in the U.S. broadcast world -- is defined by the ATSC (Advanced Television Systems Committee).

Gateway's Web site features an excellent chart defining the various "flavors" of both HD and SD that are approved within the broadcast standard:

http://support.gateway.com/s/CsmrEltrncs/DigitalTV/Shared/2517984faq42.shtml

These are television broadcast standards for the United States.

[dr.CMOK]

My favourite subject :)
As to standards, when I was reading through a lots of various sources, both "official" and "unofficial", HD is defined in soooo many ways and there was (and is now) so many marketing things, that it's hard to say what it is really.
To sum all I've got in my head, HD is set of possible resolutions (720, 1080) and corresponding set of frame rates and whether we deal with whole frames or with fields (i.e., "p" and "i", which is hard legacy of old-style TV :) ). Which to choose? I don't know, as I can't say that EBU is way smarter that, let's say ATSC, to stay at their definitions.
What personally I say to a customer? HD is a frame size, first of all. Than you have a lot of non-deterministic things or random factors. And forget about terrestrial TV - it's just different.
As it was said a lot of times here, it's very easy to create conditions when you'll get higher "framerate" with lower bitrate and vice versa. That's what in core of H.263 and H.264. One vendor prefers to choose one way of dealing with it, the other - the other way. Both have pros and contras.

PS few times when I spoke to TV guys, they even could not imagine about bandwidthes lower than 1M for SD PAL.

PPS I hope, you've got my point :)