I have a queastion about the frame rate the brodcasters are sending network progamming in. I believe ABC and FOX uses 720P, and CBS and NBC use 1080i (at least that is what the respective Atlanta stations use)

Is the Programming for 720p at 60 frames per second?

Is the 1080i at 60 fields (half a frame, or every other line) per second?

If so, 1080i/60 would appear to take only a touch more bandwidth than 720p at 60 fps. (540x1920 compared to 720x1280)

I only ask because I am wondering about 1080p/30. If it were implemented OTA, would that not be about the same bandwidth as 1080i/60? Is 30 fps sufficient for broadcasts/sports?

I can't help but wonder how a 1080p/30 car race or football game would look compared to a 720p/60 broadcast, or 1080i/60 for that matter.

I have a queastion about the frame rate the brodcasters are sending network progamming in. I believe ABC and FOX uses 720P, and CBS and NBC use 1080i (at least that is what the respective Atlanta stations use)

Is the Programming for 720p at 60 frames per second?Yes, on FOX and ABC everything is broadcast at 60 fps, though film and other 24-fps programming has repeated frames.Is the 1080i at 60 fields (half a frame, or every other line) per second?Yes, but again with repeated fields for 24-fps material.If so, 1080i/60 would appear to take only a touch more bandwidth than 720p at 60 fps. (540x1920 compared to 720x1280)YesI only ask because I am wondering about 1080p/30. If it were implemented OTA, would that not be about the same bandwidth as 1080i/60? Is 30 fps sufficient for broadcasts/sports?1080/30p is part of the ATSC standard. But sports look quite jerky at 30 fps. Think about how sports look when you see them in a film, compared to how they look on TV.

30 fps is faster than film, and I never thought action flicks looked jerky at 24 fps. Why would 30 fps be bad?

30 is close to 24, and not so close to 60.

Gee, if a question about transmission formats is not a programming question, what is? How come everything gets moved to the hardware forum?

30 fps is faster than film, and I never thought action flicks looked jerky at 24 fps. Why would 30 fps be bad?

Movie cameras have very fast shutter speeds so there is no bluriness caused by 24 fps.

30 fps is faster than film, and I never thought action flicks looked jerky at 24 fps. Why would 30 fps be bad?I think that many people see a lot of jerkyness in films. Panning shots (even slow pans) are just horrible.

Ed

Movie cameras have very fast shutter speeds so there is no bluriness caused by 24 fps.Bluriness and jerky are two different things. A static image can be sharp because the shutter exposure was very short. But the dynamic motion of subsequent frames can be very jerky if the frames are far apart in time - no matter how sharp each frame is.

Ed

I only ask because I am wondering about 1080p/30. If it were implemented OTA, . . . As was already stated, 1080p/30 and /24 are existing ATSC standards from the beginning, but esentially never used. Note that proper deinterlacing of 24 fps film transmitted at 60i will give you the equivalent of a 24p broadcast.

Ed

If so, 1080i/60 would appear to take only a touch more bandwidth than 720p at 60 fps. (540x1920 compared to 720x1280)Although some will dispute this, IMO progressive formats encode more efficiently than interlaced, even though the pixel count is nearly the same for a given period of time. Interlaced encoding has an option for modified DCT zig-zag pattern (alternate scan) to help it a bit.

MPEG-2 also has a 16x8 block size for encoding interlaced video that improves efficiency a lot. MPEG-2 has a lot of other tools for interlacing.

The real advantage I see with 1080i is that by using the pulldown flags, you can encode 1080p at 24 fps any time you want. Unfortunately the 1080i networks can't do this with how they have their affiliate feeds set up. If Fox had gone 1080i, they could have done it.

30 fps is faster than film, and I never thought action flicks looked jerky at 24 fps. Why would 30 fps be bad?

The difference between 24, 25 and 30Hz motion is really quite minimal - especially when then compared to 50 or 60Hz motion.

If you compare 60i/60p material with 24p/30p material you notice a significant reduction in the quality of motion portrayal, everything else being equal. Sampling motion at 24 or 30 times per second simply captures less motion detail than capturing at 60 times a second.

However - unlike spatial resolution (i.e. the 1920x1080 or 1280x720 sampling structures) - temporal resolution is inextricably entangled with a sharp delineation between "film look" (24/25/30Hz sampling) and "video look" (50/60Hz sampling)

In general there are all sorts of reactions triggered by production in either formats - and this is a generalisation as some people don't respond in the same way as others. (I particularly enjoy high-quality drama shot on 50/60Hz video as it has a more "real" feel for me, but this is probably because I grew up in the UK with lots of video shot drama - both for kids and adults - in the 80s)

50/60Hz stuff - as used in sports, news, entertainment and most soaps - has a "realistic", "live" and "immediate" feel - and this is enhanced if combined with traditional video camera setups and lighting, and material shot in a classic multicamera style.

24/25/30Hz stuff - as used in drama, some documentary, and some music concerts - has a more "dramatic" and "unreal" feel - heightening the suspension of disbelief aspect of drama. The "film look" - especially when shot "single camera" and lit in a filmic manner, using film lenses, has a very distinctive psychological impact - and often looks "more expensive".

As ever there are exceptions to these rules - with multicamera film sitcoms in the US, and high-budget video drama (in the UK in the 80s there was lots of high quality video drama being shot - both location single and location multicamera, and it was a world away from the overlit studio video of most soaps)

Most 24p film (and HD video) is usually shot quite carefully to minimise the motion rendition limitations of the format - particularly when it comes to fast pans (which look horrible in 24p and 30p)

Certainly sports shot on 24p - like film coverage of the Olympics or other sporting events - looks very different to the live video stuff.

I saw a press anouncement a couple of days ago from Hitachi that they will be shipping new 1080p sets soon that use a technique other then 3.2 pull down when processing film video which will eliminate the judder that still occurs with 3:2 pull down. I have been able to find it again.

http://www.engadgethd.com/2007/06/29/hitachis-reel60-processing-technology-eliminates-judder/

Sounds like they may be using motion vector interpolation.

I wonder why not come up with an LCD which can be refreshed at 48Hz as well as 60Hz.

Aren't some of the 120Hz refreshed LCDs supposed to be able to do 2:2 repetition with 60i/60p material and 5:5 repetition with 24p sources?

Any form of motion estimation - like Philips Natural Motion - fills me with horror. Broadcast quality frame rate conversion using phase correlation and block matching techniques costs 10s of thousands of dollars and is still not perfect - why would a cheap domestic processing solution be desirable? I've seen some of these systems fall apart spectactularly in the past - particularly those, like Natural Motion (or Trimension in the PC WinDVD package) that try to increase the frame rate of film to that of video or higher, by interpolating intermediate frames based on motion tracking.

...
50/60Hz stuff - as used in sports, news, entertainment and most soaps - has a "realistic", "live" and "immediate" feel - and this is enhanced if combined with traditional video camera setups and lighting, and material shot in a classic multicamera style.

24/25/30Hz stuff - as used in drama, some documentary, and some music concerts - has a more "dramatic" and "unreal" feel - heightening the suspension of disbelief aspect of drama. The "film look" - especially when shot "single camera" and lit in a filmic manner, using film lenses, has a very distinctive psychological impact - and often looks "more expensive".


Nice comparison, sneals. I've noticed this effect also - the "video look" looks real, immediate and has a certain snap to the picture, to quote an old RCA studio camera brochure. Film looks more distant and dreamy and is better for storytelling in that respect. The film look also has a lot to do with the gamma curve of the camera - a film-look picture compresses the dynamic range of the image, which has a lot to do with that "distant, dreamy" look, because we don't perceive things that way in real life. The video-look transfer curve more closely resembles how our eyes interpret the contrast ratio of the things we see, which is the other reason why the video look appears to be more real and immediate.

I stumbled upon an example of how the temporal aspect of "film look" operates. Back in the 80s we were shooting a local rock band in a studio. The band wanted to have various video effects, so I twiddled with a framestore synchronizer to produce a strobe effect, essentially dropping a handful of frames every second. Whenever I threw the switch to kick in the effect, I was astonished to find that the video suddenly looked lile film! The only thing that changed was the effective frame rate; slowing it down just a bit produced that filmic motion judder that completely transformed the look of the video.

The band was impressed, and I was amazed. :)

A lot of people are very fond of the film look. ;)

- Tom

I stumbled upon an example of how the temporal aspect of "film look" operates. Back in the 80s we were shooting a local rock band in a studio. The band wanted to have various video effects, so I twiddled with a framestore synchronizer to produce a strobe effect, essentially dropping a handful of frames every second. Whenever I threw the switch to kick in the effect, I was astonished to find that the video suddenly looked lile film! The only thing that changed was the effective frame rate; slowing it down just a bit produced that filmic motion judder that completely transformed the look of the video.

The band was impressed, and I was amazed. :)

Yep - repeating fields (i.e. ditching one of the two fields) in a video source gives it a film like motion characteristic. Over here lots of drama and documentary is shot 16:9 SD 50i, but processed in post production to give it a 25p film-look motion characteristic.

The two recommended ways of doing this are either to use a Snell and Wilcox ARC which has high quality multiple-field processing, and rather than use it to aspect ratio convert you use the option it has to process 50i to 25p. The best solution currently available, and the BBC in-house "best route", is to use an S&W Alchemist standards converter (also from S&W) to do a similar thing - standards converting from 50i to 25p.

Dr Who - the popular BBC scifi drama is shot 50i SD on DigiBeta camcorders and processed using the Alchemist route currently I believe, but previously used the S&W Arc for the first of the new series) Both of these solution retain a reasonable amount of vertical resolution - whereas dropping a field is a horrible technique, which throws away vertical information and delivers an aliased look, though as an effect, when a simple DVE was all you had, it was the only way of doing it (and so we did...)

Of course in the HD domain it is much more common to be able to shoot natively in 25p rather than having to shoot 50i and convert (as is the case of SD where high quality DigiBeta SD camcorders that shoot 25p are not widespread)

Dr Who - the popular BBC scifi drama is shot 50i SD on DigiBeta camcorders and processed using the Alchemist route currently I believe, but previously used the S&W Arc for the first of the new series)

All series have been filmised on the Alchemist -- certainly I was told that whilst SEason 1 was being edited. S1 was conformed tape-to-tape (the EDLs being slipped to correct for the delay introduced by the Alchemist) and that tape was then used for the basis for effects plates and then graded. From S2 onwards they've been grading (and I presume finishing) with a Baselight (and of course, I think words were had about the camera setup and the horrendous overuse of promist filters) -- which has probably helped the image quality.

Steven

Yes, on FOX and ABC everything is broadcast at 60 fps, though film and other 24-fps programming has repeated frames.Yes, but again with repeated fields for 24-fps material.Yes1080/30p is part of the ATSC standard. But sports look quite jerky at 30 fps. Think about how sports look when you see them in a film, compared to how they look on TV.

Doesn't 1080i60 broadcast material such as CBS, TBS, and NBC translate to presentation as 1080p30 on my 1080p DLP television set? The Superbowl, MLB playoffs, etc have looked pretty good to me.

Doesn't 1080i60 broadcast material such as CBS, TBS, and NBC translate to presentation as 1080p30 on my 1080p DLP television set? The Superbowl, MLB playoffs, etc have looked pretty good to me.No.

Sports and live video are acquired in native 1080i60, which means you have 60 different fields, each acquired 1/60th of a second after the other. You do not have two fields from the same frame, you have one field (i.e. one-half) from every frame -- the fields do not line "line up" to form a 1080p30 frame unless you are dealing with a static shot with no movement from one second to the next.

Most 2006 and 2007 displays interpolate the missing half of each frame to create a full 1080p60 signal through a process known as motion-adaptive deinterlace. Adjacent fields are compared to determine what pixels are in motion. Areas of the picture that aren't in motion -- such as background scenery that did not move in the previous 1/60th of a second -- can be weaved together at full 1080p resolution. Areas of the picture that are in motion -- and did move in the previous 1/60th of a second-- are created by bobbing, or in some cases, averaging the information in adjacent fields, and will vary in resolution between 540p and ~1080p. Whether pixels in motion appear as 540p or closer to 1080p depends on the rate of movement, type of movement, as well as the quality of the video processor in the display. Not all processors do motion-adaptive deinterlacing equally well. Some implementations may introduce more artifacts than others.

Film-sourced content such as movies and series is different. Content like CSI and Heroes is acquired in (or telecined to) 1080p24. In order to create a 1080i60 signal, each 24p frame is split into two fields; because 24/2 = 48, some fields are repeated while others are not. The best displays can detect this 3:2 cadence to determine that the original source is 1080p24; then they can drop the repeated fields and combine the matching field pairs to obtain the original 1080p24 source without interlace artifacts. This process as known as inverse telecine. After the original 1080p24 source is obtained, the progressive frames can be repeated to form a 1080p60 or 1080p120 signal (depending on your display). Unfortunately, high-definition cadence detection is computationally intensive and most <$3000 displays like your Samsung DLP cannot do it; instead, such displays apply motion-adaptive deinterlace on all 1080i inputs, regardless of the original source.