XDcamEX vs JVC GY HD250

[Steve Mullen]

Originally Posted by Kevin Shaw

My understanding is that the EX1 has a 1080p recording mode, so if it maintains full resolution at that setting it should look pretty good compared to the JVC cameras. And there are other reasons to expect the EX1 to be stiff competition, so it's not just about pixel counts and frame rates.

It seems lots of folks are throwing around the term "1080p" without realizing that the only two useable frame-rates are 25p -- ONLY in R50 -- and p24 -- ONLY in R60. And, either frame-rate is only useable where low-frame rates are desired.

When smooth and clear motion capture is needed, 1080p is not available. You'll have to shoot 720p50 or 720p60.

So there remains a conflict between fine detail (1080) and clear motion (progressive). The only thing that has changed is that before we had to select Sony or JVC -- while now we can select between formats on the EX1.

Whoever can get 1080p50 and 1080p60 in production -- gets the prize. (I suspect JVC will announce at NAB 2008 as they are committed to progressive.)

What's odd is that the EX1's CMOS chips and DSP are already working at 50Hz/60Hz. It simply isn't recording it. Which is strange because solid-state recording shouldn't be a limiting factor.

[Kevin Shaw]

Originally Posted by Steve Mullen

When smooth and clear motion capture is needed, 1080p is not available. You'll have to shoot 720p50 or 720p60.

So the EX1 has a 720p60 recording mode like the JVC cameras and a full-raster 1080p24 mode, both using higher bandwidth? Sounds like healthy competition to me...

[Werner Wesp]

Originally Posted by Thomas Smet

I have done a few tests now with motion video. I have created many samples of animated video including simple fast moving objects and scenes that have a lot of 3D rendered hair and fur. In the end with proper filtering the 1080i versions and the 720p both playing back upscaled to 1080p 60p look almost exactly the same. I would share these samples but I cannot think of a way to share 1920x1080p 60p video with you guys. All the tests I have done were in special playback software I wrote so it could run the video at 60p.

I would say the 1080i was about 1% sharper which was kind of an illusion really. The reason why it looks sharper is because of the interlacing. Because the video is interlaced you end up with 1080 unique lines of detail that are all different. With progressive video the lines tend to blend into each other making a more natural looking image. With interlaced however you do not see this blend as much because of how the fields are split. 1080i does work very well for HD and while there can be edge artifacts they do not show up as much as some would think. 1/60th of a second is pretty fast and before you could notice anything missign the missing part is replaced with the next field and so on. The beauty of 1080i however is that even when you have a single field it still looks like a 1080 image. A single field with the lines alternating will look much sharper then a 1920x540 rendered image so you cannot say 1080i only has 1920x540 per field. Sure it has that many pixels but they are spread out better so they look more detailed.

This is why you can't use animated graphix as base. When you resampled that to 1080i, probably no anti-flickering was added. You haven't checked your 1080i on a 1080i CRT, I suppose.

Furthermore, most motion graphics aren't subject to the compression that is less suited to MPEG compression, since there's no higher order correction for redundant info in between fields.

1080i has just 1920x540 per field (or 1440x540). On a CRT without deinterlacing filter is seems to have 1920/1440x1080 per frame, still 1920/1440x540 per field.

If you really want to test: stitch a few videos in 720p50 together to get 1080p50. Then downsample to 720p50 and to 1080i50. The difference is there. I'd say it is quite something, others don't mind or don't see it - perception is subjective and it need to be said both 720p and 1080i look rather good (especially compared to SD, even PAL).
When you slow down the 1080i and the 720p it is a whole different game: no-one remains that doesn't see the difference.

[Thomas Smet]

Originally Posted by Werner Wesp

This is why you can't use animated graphix as base. When you resampled that to 1080i, probably no anti-flickering was added. You haven't checked your 1080i on a 1080i CRT, I suppose.

Furthermore, most motion graphics aren't subject to the compression that is less suited to MPEG compression, since there's no higher order correction for redundant info in between fields.

1080i has just 1920x540 per field (or 1440x540). On a CRT without deinterlacing filter is seems to have 1920/1440x1080 per frame, still 1920/1440x540 per field.

If you really want to test: stitch a few videos in 720p50 together to get 1080p50. Then downsample to 720p50 and to 1080i50. The difference is there. I'd say it is quite something, others don't mind or don't see it - perception is subjective and it need to be said both 720p and 1080i look rather good (especially compared to SD, even PAL).
When you slow down the 1080i and the 720p it is a whole different game: no-one remains that doesn't see the difference.

I have tested all of this. My graphics all had filtering in 3 ranges from small to higher. I even tried different ways of filtering the video such as blur filters and even down scaling slightly and scaling back up to simulate lower detail. None of my tests had sharp crisp graphics because I always design my graphics with some level of filtering to reduce DCT based image artifacts when compressed. The graphics from 3D Studio Max used the video antialiasing method which simulates video filtering and is actually very soft in detail. In fact some people may even say I filtered a little too much which is why I also tried this a few times with less filtering.

What I have found is that even if you did start with totally unfiltered video the 1080i version still wasn't really that much more detailed and they both ended up pretty much looking the same in terms of detail although unfiltered the 1080i looked like garbage because it flickered all over the place while the 720p still looked very clean.

I have even stritched together uncompressed live SD captures to create fake HD but this can only go so far because SD cameras tend to filter more then what you need with HD. This is also a almost useless test for motion because you have no way to capture 1080i 60i and 720p 60p at the same time to test the motion. I mostly use this method to test encoders and processing software.

As much as I hate 1080i it really isn't fair to call it 1440x540. If you create a image that is 1440x540 pixels in size and then one that is 1440x540 but with space alternated in between the second one will look sharper. 1080 with every other line duplicated will look sharper then 540 pixels blown up to 1080. It is all about the illusion of detail and that is exactly what it does. It doesn't really work to think of interlaced in terms of pixel size because there are so many optical illusion factors in place that it just doesn't work.

[Steve Mullen]

Originally Posted by Kevin Shaw

So the EX1 has a 720p60 recording mode like the JVC cameras and a full-raster 1080p24 mode, both using higher bandwidth?

And, a 720p24 mode.

That's why the ball is now in JVC court.

They could do a handheld version of the HD250 and/or push the art with 1080p50 or 1080p60. Europe needs 1080p50 immediately!

Or, give us ProHD 422.

Or, all of the above.

A harddisk will take the higher data-rates needed for these.

[Thomas Smet]

I am pretty sure 1920x1080 at 60p is not possible with mpeg2 so a move to a very high level of AVC would be needed in order to get that type of video.

While we may at some point get some funky camera to record a funky form of 60p you guys will be waiting a very long time for a delivery option for that type of video. If you could shoot that type of video you would have to choose to deliver it as 1920x1080ix60i or 1280x720px60p in which case you would have been better off just shooting in that format to begin with.

For the very tiny quality boost you would get I just don't see how spending twice the amount of bandwidth is worth it. No TV station is going to eat up double the bandwidth just for that tiny boost in quality. Most consumers who are still very happy with DVD is going to be perfectly happy with 720px60p and 1080ix60i for a very long time yet.

This whole 1920x1080x60p thing is just insane and is more of a sick fantasy then anything of any great use other then to waste money.

[David Heath]

Originally Posted by Thomas Smet

While we may at some point get some funky camera to record a funky form of 60p you guys will be waiting a very long time for a delivery option for that type of video. ...........

For the very tiny quality boost you would get I just don't see how spending twice the amount of bandwidth is worth it. No TV station is going to eat up double the bandwidth just for that tiny boost in quality. ........

This whole 1920x1080x60p thing is just insane and is more of a sick fantasy then anything of any great use other then to waste money.

Sorry - I disagree, and the latest research has shown that the additional bandwidth required to transmit 1080p/50 is nothing like twice as much as for 1080i/25. Although the initial data rate may well be twice as much, it compresses far better, so the COMPRESSED data rate is far less than that would suggest.

The BBC in the UK has just released a detailed report about it's plans to start a full HD service next year - http://www.bbc.co.uk/bbctrust/assets...onclusions.pdf - and one section is relevant to technical issues.

"3.39

We think it likely that broadcasters may face a variety of pressures, including regulatory, to move towards the 1080p picture resolution – capability for which is not available in current consumer display equipment. But we would expect that future transmission of 1080p pictures would be backwards compatible with current display equipment. So there should not arise an issue of consumer disadvantage. Nonetheless, we would expect the BBC Executive to make any move towards 1080p with sensitivity towards the current choices facing consumers who equip themselves to receive HD."

From which it seems they see a move to 1080p/50 highly likely - the only concern being not rendering existing home displays obsolete.

[Werner Wesp]

Originally Posted by Thomas Smet

As much as I hate 1080i it really isn't fair to call it 1440x540. If you create a image that is 1440x540 pixels in size and then one that is 1440x540 but with space alternated in between the second one will look sharper. 1080 with every other line duplicated will look sharper then 540 pixels blown up to 1080. It is all about the illusion of detail and that is exactly what it does. It doesn't really work to think of interlaced in terms of pixel size because there are so many optical illusion factors in place that it just doesn't work.

Once more: at 1/50th (1/60th) of a second it IS 1440x540. Due to displacing it look somewhat more (+/-750) when playing, I never denied that. but every FIELD is just 1440x540.
Since 720p50 has no fields, just full frames, it has full resolution every 1/50th (1/60th) of a second.

Stitching together SD can never work, because there's no 50p mode is SD (unless with JVC HD100). You have to stich some 720p50 together to get some 1080p. Never try to get decent progressive images out of interlaced onces - you always loose quality, that's just the raw laws of physics.

[Werner Wesp]

Originally Posted by David Heath

Sorry - I disagree, and the latest research has shown that the additional bandwidth required to transmit 1080p/50 is nothing like twice as much as for 1080i/25. Although the initial data rate may well be twice as much, it compresses far better, so the COMPRESSED data rate is far less than that would suggest.

Indeed: All or virtually all compression schemes work far more efficiently with progressive images, therefore you can have less compression artifacts in 1080p then in 1080i, withouth doubling bandwith - although, the larger the bandwith, the better of course.

Obviously 1080p50 and 1080p60 is no sick fantasy - it is the logical next standard and a serious improvement over 720p50 (and an even bigger improvement over 1080i50). It is defenately no slight improvement. Furthermore is it a logical stardard that will fit all LCD- and Plasma-displays, as they are pushing that new standard (known by regular consumers as "Full HD").

[Kevin Shaw]

Originally Posted by Thomas Smet

I am pretty sure 1920x1080 at 60p is not possible with mpeg2 so a move to a very high level of AVC would be needed in order to get that type of video.

The Convergent Designs XDR recorder discussed here recently includes a 1080i/p recording mode using MPEG2 compression at variable data rates of 50 or 100 Mbps. http://www.dvinfo.net/conf/showthrea...d-sdi+recorder

I'm not sure why we're discussing 1080i versus 720p here given the original topic of this thread, which is the XDCAM EX versus the JVX HD-250U. The EX can record 720p60 like the JVC (but at higher bandwidth) or record in 1080 formats with twice the real-world resolution, so all around better than the JVC by any technical measure. If you like shoulder-mounted cameras that's a different discussion, and form factor is an important consideration in picking a camera.

[David Heath]

Originally Posted by Werner Wesp

Indeed: All or virtually all compression schemes work far more efficiently with progressive images, therefore you can have less compression artifacts in 1080p then in 1080i, withouth doubling bandwith - ...........

I don't think it's just the progressive nature. Go to higher resolution frames and it's possible to use higher levels of compression, even when both systems are progressive - hence it still shouldn't be 2x the 720p/50 data rate after compression.

Originally Posted by Kevin Shaw

........the original topic of this thread, which is the XDCAM EX versus the JVX HD-250U. The EX can ....., so all around better than the JVC by any technical measure. If you like shoulder-mounted cameras that's a different discussion, .......

All true, and once accessories like radio mic receivers and camera lights start to be used, the JVC form factor starts to take on even more significance. It's also pretty easy to add a Firestore to a JVC camera, and still end up with an ergonomic package, and some users may find that tape+tapeless combination a big draw.

[Thomas Smet]

Originally Posted by Kevin Shaw

The Convergent Designs XDR recorder discussed here recently includes a 1080i/p recording mode using MPEG2 compression at variable data rates of 50 or 100 Mbps. http://www.dvinfo.net/conf/showthrea...d-sdi+recorder

I'm not sure why we're discussing 1080i versus 720p here given the original topic of this thread, which is the XDCAM EX versus the JVX HD-250U. The EX can record 720p60 like the JVC (but at higher bandwidth) or record in 1080 formats with twice the real-world resolution, so all around better than the JVC by any technical measure. If you like shoulder-mounted cameras that's a different discussion, and form factor is an important consideration in picking a camera.

Yes that is for 1080i 60i or 1080p 24p,25p or 30p. Nowhere does it ever say it can encode 1080p 60p.

[Werner Wesp]

MPEG2 is scalable to 1080p.

[Kevin Shaw]

Originally Posted by Thomas Smet

Nowhere does it ever say it can encode 1080p 60p.

And neither can the JVC, so I don't see how that's relevant to this comparison. In any case, the EX1 works well and makes a fine alternative to other HD cameras in the same price range, depending on your particular needs.

[Thomas Smet]

I was commenting on the fact that no camera while still using mpeg2 will be able to do 1080p 60p. This includes HD broadcast as well. So if JVC or SONY sticks with mpeg2 then you will not see 1080p 60p. Also until the point when we can make Blu-Ray and HD-DVD discs with VC1 and AVCHD encoding you will have no way to deliver 1080p 60p.

So while in a few years 1080p 60p may be nice it is pointless to think about it right now. This is why it is a fantasy. Until we can shoot with it and make use of it it is a fantasy. Sure maybe some people are working on a solution but it isn't ready yet so it is pointless to get all worked up over a format that isn't even around yet. When it does come out it may be awhile before any of us will be able to deliver with such a format.

This is relevant because I am trying to point out for now we can use 720p 60p or 1080 60i or 1080p 30p. So we should all go back to thinking about using those formats and stop thinking about 1080p 60p.