FYI: Super Encoder compared to HD-100 encoder.
 

Hi,

As with alot of you, I have had my hands on a GY-HD250 and shot some footage. Most notably the 60p footage looks like "Video" a la 60i which should make the broadcaster jump for joy. Getting slow motion is a snap with the 60fps footage and it is extremely smooth as you'd expect.

I was most interested in the encoder though and made a small video to explain my process of comparing the HD-100's encoder to the "Super Encoder". You may be amazed at how much better the Super Encoder is compared to it predecessor. Click here for WMV. This should play for both PC & Mac.


For kicks here is a Sample Slo Mo which was a snap to do in the NLE. The clip is slowed down to 40% (ie 60fps to 24fps). Easy to do...

Regards,

S.Noe

Stephen,
Once again you have been a great resource of information!
Well done.

I was hoping JVC would improve their encoder. It appears they did!
I've been asking this exact question and you have provided the answer.
It looks like I need to start saving some coin.....

Does this super super encoder on the HD250 is also for "old" 25-30p, or only for the new 50-60p ?

Hi Stephen,

Thanks for the demo, I'll be getting my 250 next thursday!

I can't get the Slo Mo movie to work. I hear the soundtrack but don't see the video. I tried Quicktime with Flip4mac and I tried VLC.

The other movie (Super Encoder) is working fine.

Same's happening here

Thanks Stephen, great stuff!

Do you have any idea how much of the image improvement with the 250 over the 100 is due to the improved MPEG "Super Encoder" alone, compared to the new 14 bit A/D of the 250? I'm not clear where the line is drawn between the new specifications of the 250, or if they are one in the same and
more integrated than I understood.

If unique, and the improvement was totally on the encoder side then could you get similar results on the 100 when bypassing tape via component uncompressed? Or is this better asked of Ken or Carl at JVC?

Sorry, not trying to be the "why kid", just curious.

Although the new 14 bit A/D and the new encoder are separate circuits - the A/D happens before the encoding - they both contribute to the overall improvement in picture quality.

I'd expect that the A/D converter would be the reason for the much better noise supression. The lack of blocks in the blue channel would be the the result of the better Super Encoder.

On the HD-100 you'd get much better results from the component out compared to the encoded information on the tape, but the HD-250 is even better merely because of the better A/D converter. Face it, the HD-250 is better in every way than the HD-100 and the price reflects it. I'd expect the HD-200 to be in the same ballpark as the HD-250, thus the higher price (than the HD-110).

Either way, we are all winners with ProHD.

HD-250's benefits also span to all available framerates on the camera (ie 24,25,30,50 & 60).

BTW: There is no HDV-SD50 or 60 modes on the HD-250. They do not exist in the menu's.

I take it the PAL version will do 50fps slow mo ?

Andy.

I'll do HD in 50p, and that's easily downconverted to slow mo PAL 25p progressive (or 50i, if you really must)

Yes, but I wonder of there are HDV60P modes on the Euro version as well?

If NTSC has 50fps in theirs then PAL will have 60fps in theirs, the only difference are the standard definition formats will only be local, eg. NTSC will only get DV60i while PAL will only get DV50i

It's strange that you are having issues with the blue channel. My problem with my HD100 seems to be the RED channel. Whenever I do weddings I notice the blockiness and pixelation on the roses while everything else looks fine.

That is your render codec and not the native transfer. What is your editing system?

Same here. Stephen can you fix that when you get a chance? Thanks

It was jerky for me too but i dropped it into power dvd and it played fine , try your dvd player.

Andy.

Say Stephen, I was wondering for trading in my HD101 for a 251 or 201, but what worries me is the image quality on 50p. As I understand it, the 50p compression with the new codec is also 'only' 19.7 Mbps - long GOP this time of course - ... How does that look compared to the picture quality of the HD101's 25p?

Does anyone know when you record 24p or 25p on the HD251 whether that is long GOP or short GOP?

This thread should help you: Click Here.

Either if if the GOP structure is longer (12) or shorter (6), it's still the same fraction of time to the framerate it's applied to (ie 1/5 of a second).

Yes, I did know that. What I meant to ask was: If you put the HD251 in 24p or 25p for recording, does it still encode in a 12-frame GOP, or is it then done on the 'old and reliable' 6-frame-GOP-way?

Furthermore. And this is something I'm worried about. Obviously it is still the same amount of time that's encode in 1 GOP, but it's TWICE the uncompressed data that needs to be compressed in that GOP (there are twice as many frames - the fact that it's the same time-interval is datarate-wise meaningless).

Obviously, the longer the GOP, the more efficient the encoding (and the more profound the errors and drop-outs...), but doubling the number of pictures in the GOP won't make it twice as efficient, so overall, one would expect a degrading in quality. However I expect the quality to be about the same in the real world: due to the higher temporal rate the frames will have a smaller difference between them and they will have more defined edges, because of the shutter speed that'll be at least twice as high - both characteristics are making encoding easier and thus more efficient...

It isn't playing jerky, it isn't playing at all. We don't have Power DVD for OSX. That's why I tried VLC.

Is it the demo video that's not playing or the example slo mo video?

For me it's the example slo mo. I can only hear the music. The super_encoder file works fine.

Stephen, since you tested the 250, can you comment on how much light it needs (shooting ay 50p - with a 100 shutter most likely)?

I'd say (unscientifically) it takes exactly the same amount of light as the HD-100 would require. I think the CCD's are exactly the same hardware as what's in the HD-100. It's the encoder that's different and the A/D process.

Our comments were that it was cleaner than the HD-100 comparitavely. This is probably because the encoder is better and not to do with the lens (which was stock 16x) or CCD's (which are 1280x720 probably the same as HD-100).

If it is the same, you should need more light to expose 50 frames in once second, instead of 'just' 25. But no remarkable difference there? You haven't tried it in a low light situation by any chance, I suppose?

I'm actually interested in upgrading from my 101E to a 200, which should be the 250 without the SDI, but my 101 already needs a lot of light for nice images - so shooting with the 200 at a double framerate and a double shutter speed scares me a bit...

Yes it's the slo mo video.

The slowmotion with the default shutter speed is impeccable and I didn't really see any difference in lighting need for interior. The encoder is so much better you can get away with using gain without introducing very much noise. Really they did their homework.

It doesn't matter. The HD-101E still shot a 50p video and the DSP dealt with a 50p stream. It was only the encoder that had to drop every other frame to give you a 25p encoding. This is why through the component outputs you could get the full 50p video. The same amount of pixels and data are still being pushed through the image block as before. The only difference now is that the encoder can finally handle the full 50p stream that comes from the DSP. Due to the better A/D handling and less noise you may find the HD200 to be a little bit better in low light due to the fact that you may be able to use a little bit more gain then you had in the past with the HD101E.

When shooting 50p, your standard shutter speed will be 100 (or up - for me it'll mostly be 100). that's twice as fast as the standard shutter speed on the HD101, so There needs to be a difference in adequate light.

But, I did indeed forget that the camhead of the HD101 already works in 50p, so the amount of light will be the same as amount the hd101 needs with a shutter of 100.....

Great point Thomas. You're absolutely right. No wonder the light requirement looked identicle (to me).

You should not use a shutter speed of 100 if you shoot 50p. The shutter speed should also be 50 no matter what format you record in. Remember both cameras are really shooting the same 50p but the older one had to dump the frames down to 25p to go to tape. You still use the same 50 shutter speed however for the same type of motion. You would only use a 100 shutter speed if you plan on slowing down the footage to 50% and use it as 25p slow motion. The reason for this is because when it is slowed down it will act like a 50 shutter speed again so it will look natural and have the same style of motion blur as your normal speed 25p footage. Think of the HD101E as not any different then shooting with the HD200. The frames will look exactly the same except the 101E footage with have every other frame dropped due to the limits of the encoder. Just because you will now be able to record 50p doesn't mean the shutter speed has to change. The frames in the camera are still the same you just now get to record all of them.

Hhmmm, with the shutter speed the same as the time interval for recorded frames you normally don't get those natural results. Of course, at 50p it might be difficult to see. (just try 25p at shutter 25... you'll know, i'm talking about the 180° shutter look)

Anyhow, unless it is staged you never know beforehand what piece of footage you'll be slowing down. The interesting part just consists of the fact you CAN slow everything down smoothly if you want.

If I wouldn't be slowing it down anyway, I'd be shooting in 25p - which looks a lot more filmic, and you have to respect the cinematic rules in order to keep it looking good. Everything I'd shoot would be on 50p with shutter 100 then - but you are right, it would look as a HD100 with shutter 100 then...

50p is no different then 50i where 50i would use a shutter speed of 50. With 50i you have 50 interlaced fields. The only difference between interlaced and progressive is that with progressive each moment in time is the full resolution of the frame and not half the resolution. a shutter speed of 50 is the normal value of shutter speed regardless if you were shooting 12, 25, 50 or 100 fps.

Now if you prefer to shoot a shutter speed of 100 thats your choice but the HD200/HD250 is in no way worse in low light because you choose to shoot with a shutter speed of 100. In the case of 25p or 50p they represent the same moments in time it is just that the 50p has more images to represent that moment in time.

Remember an interlaced camera will usually shoot with a shutter speed of 50 or 60 depending on if it is PAL or NTSC. Those interlaced frames show us the same moments in time as a 50p or 60p video. So in order to have a natural 50 hertz looking video just like the motion you would get with interlaced cameras you will use a shutter speed of 50.

With 25p you would still use a shutter of 50 because the shutter represents that type of time interval. If you use a shutter speed of 25 with 25p you get a fake amount of motion blur because a shutter speed of 25 is not natural. By shooting 25p you are shooting at half the framerate but those frames still need to represent the same moments of natural time.

You also have to remember that with 24p and 25p the 180 degree rule may apply but with 50p and 60p it is no longer film motion but video motion so the 180 degree rule doesn't really apply anymore. The extra frames help reduce the jitter and make everythign look natural.

Not entirely. If you would shoot 50i and slow it down, you still get the 180° shutter, because the footage is de-interlaced before slowing down (so it'll effectively be like half-res 25p before slowing down). In order to be able to slow any piece of 50p footage down - and keep it looking natural - you'll have to aquire everything with a 100 shutter. In normal frame rate (i.e. not slowed down 50p) it is probably to fast to see it isn't natural. Still, motion recorded in 1 frame is the motion that appears in the total interval - i.e. 1/50th of a second.

I cannot see the point of shooting 50p with a 50 shutter-speed. definition won't go up (because the shutter speed is the same), slowing down isn't interesting because it'll look blurry and unnatural anyway (because the shuttertime is as long as the framerate-interval). The only thing is that you'll be able to pan at any speed you want, instead of respecting the filmic rules to keep it looking good... but your final result will look less crafted then anyway. For non-slowed-down clips 25p is fine (imo), you just have to craft your shooting skills. 50p definately opens up new possibilities, but only at shutterspeeds of 100 and up...

Not at all. 50p records full frames while 50i records 25 frames that consist of 50 half frames. But 2 adjascent fields do not share any information in their image - the frames in 50p do...

Furthermore, suppose you shoot 100 fps at a shutter speed of 50 (which you say is a normal value), what would be the point of shooting 100fps then? 2 following frames would be exactly the same because they are recorded in the same time interval - it would be virtually like shooting 50p. Try to shoot 25p with a 12.5 shutter speed - you'll know what I mean. Obviously a shutter speed of 50 would be fast enough not to notice when shooting e.g. 100 fps, but it would serve no point of recording 100 frames then.

This is just plain wrong, it depends on the deinterlacing method. A bob, which most tape decks use, will effectively create half-res 50/60p. Adaptive deinterlacing and motion compensation can create what appears to be full-res 50/60p. Field Blending is the only deinterlacing technique which would result in half-res 25/30p.

Again, incredibly wrong. Watch a sports broadcast some time, 99% of the slomo you see is shot by cameras operating at a native 1/50 or 1/60 shutter. Yet that slomo does not look any less "natural."

Because you are living in your own very tiny indie film world while completely ignoring the fact that people use this camera for other things. Remember that the 50p and 60p capabilities of this camera aren't simply for being able to shoot slomo, but primarily for being able to shoot at the native frame rate of the broadcast HD standard of your country. Being able to slomo it for 24p is just a bonus. Shooting video for broadcast requires the look resulting from a frame interval shutter speed

You have obviously never shot sports highlights. I invite you to go to a hockey game and shoot from the glass and tell me that 25p is fine. Because this sort of situation is exactly why I waited for the HD250 over the HD100.

Wow. You don't even know how your camera works. Not only is your argument irrelevant (we're talking about shooting at the reciprocal shutter speed of the frame rate, not saying that 1/50 is the "ideal" shutter speed), when shooting at 1/12.5 the camera is shooting at 12.5 frames per second and pulling that frame down over 4 50p frames. You are not shooting "25p with a 1/12.5 shutter", you are shooting 12.5p. If it were actually physically possible to shoot with a shutter speed longer than the frame interval, the effect would be of motion blur from adjacent frames overlapping. From a temporal resolution standpoint it probably would be pointless to shoot that way, but it could be a rather interesting effect if you want maybe a "dreamy" sort of look. After I submit this post I'll work up a demo in my 3D software, which does allow these sort of weird shutter effects.

I'm not sure this is entirely accurate either. The slow motion I see on TV sports (for example footbal or gymnastics) is much too sharp in freeze frame to have been shot with a 1/60 shutter.

I think super motion cameras are possibly more the standard, shooting at 180 frames a second (NTSC) at high shutter speeds. These cameras also send out a regular video feed, etc. etc.:
http://www.evs.tv/Products/SuperMotionMode.asp

I do live broadcast sports production for a living. When I say this stuff, I'm not pulling it out of my ass, I'm saying it because I've run the cameras, I've been in the trucks, and I've looked at the camera CCUs that say they don't have shutter engaged. Of course it is up to the individual preference of each video operator whether they use shutter, but I know that if someone made a habit of putting shutter on everything, they'd get a lot of complaints from camera operators who won't like the loss of two stops of exposure, especially with a zoom extender that's also cutting out two stops. Focus is hard enough at the end of a 70x lens without the video operator opening the iris even more with unnecessary shutter.

I'm well aware of the existence of supermo cameras, and they're not used nearly as much as you would think. While some big shows like Monday Night Football can get trucks built specifically for their shows, most shows rent trucks built by a truck company that's trying to do it for the least amount of money possible. For most truck companies it's simply not a worthwhile investment. I've only personally been in two trucks that have had a supermo camera, the MNF camera truck, and a truck that was doing college football for ABC. This is out of countless trucks from many different truck companies.

The other big issue with supermo is that the camera taken live on the air looks very juddery and the picture quality does not match the other cameras in the show. It's enough of a downside that you'll generally only see it used in shows that can afford to hire enough crew where you can have a guy running a camera that will only show up in replays. The one exception I've seen was the recent NBC Stanley Cup coverage where they used supermo on the high-tight shot, which for hockey is taken live very often. The quality difference between the high tight and all the other cameras was blatantly obvious.

I'm sure you are right. There's just something that I can't understand about it. I don't understand how they make frozen images of fast moving people and objects that are completely sharp but are exposed for 1/60 of a second.

But then I also don't see how they keep everything in focus with the distances changing so fast from far to close... I guess just experience and turning the focus control based on the distance of the object from the lens.

Then there are the flying cameras that are also in focus. Are they just very wide angle and using a fixed focus?

..........