25fps 19mb/s HD1/HD10 idea.

[Wayne Morellini]

Hello, just was reading through the latest mod thread, and it occurred to me a possible method for getting 25fps on the old HD1/HD10.

This has crossed my mind before but I never got to posting it. Consider these ideas a present to HD1/10 community, along lines of what a number of people have asking for many times in times past).

All the mods below are theoretical, I don't have a JVC (still waiting for the 25fps version ;).

Very few people here will have the skill and money/camera/s (assuming it works right on the first camera) to spare to attempt these, and everybody else should not. If this works.

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Use a synced shutter mechanism (new external shutter, even internal) to blank out every 6th frame. Then, strip the blank frame and modify the footage to 25fps.

As I understand, from DV codec, that it can move some encoding into the next frame, mpeg2 should be able to do this better. Now the skipped frame should be very small, and the coding go to the surrounding frames (It would help if gain were turned right down and shutter sped right up for the skipped frame, to reduce noise).

Getting rid of the Jump:
It is complicated though, because you will lend up with a jump after every 5 frames. But if you can get control of sync then you can smoothly advance the timing of frame successive frames, enough to smooth out the jump (so that the 6th blank frame happens right up against the 7th frame). I though Lanc had a sync ability, si that right?

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Now separately, there was a guy that removed the lens on his Sony Z1 and put a good SLR lens on instead (Nikon I think). Full Manual Control. Now this is likely going to ruin your camera forever because things could pop out in bits and pieces and you will never be able to figure out where to put them back, or even how they were put together in the first place, or just plain break it ;). So, unless you are a rich man with a HD1 you no longer want, and can afford to throw on the tip, or do this with it and then throw it on the tip, DON"T TRY IT.

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This could give you 25/24fps and full manual control. The two of the three things that people here always ask for as a mod (The other being 25Mb/s).

So, has anybody tried it, or would like to?

Using a suitable condenser (and they need to fit the lens sensor area characteristics) the lens should deliver (from what I understand) better DOF, more light (lower light performance) and a nice set of ND filters should give better latitude. A variable ND filter is probably best because of the extra light.


Thanks for all the conversation in times past. Have fun, a delayed happy new year to all.

[Wayne Morellini]

Correction, I looks like it was an FX1 with Nikon lens:

http://www.eidomedia.com/hdv/

Would be a good place to start.

Lens Systems are very touchy (hence take caution with condenser (macro)). Also, from an engineer I know, something like, going too wide of aperture will introduce aberration/washout, as the micro-lens arrays have only a certain range (and prisms too).

[Ken Hodson]

Hey there Wayne. Been doing a lot of thinking for a guy who doesn't own a cam ;>)
As far as rigging something external to get 25p out of 30p, I think it would be very difficult. A software solution is better suited and has been done. JVC did a tech tour of the HD10 in Europe in the early days of the cam, demonstrating 30p to 25p conversion. Canopus was the software. I have never seen or attempted the conversion myself, but I will give it a try with a few software packages and report my results. I have read befor that if you want 24p from 30p the best route is to first go to 25p then convert to 24p they way PAL users have been. 4% speed-up then adjust the audio pitch.
I'm very interested in the lens job. I know little about those type of lens. Are you saying the lens would provide full control? Lock the cam in the shutter you want, then the lens can be adjusted for the rest?
As far as your third want, 25mb/s, this is a little unfeasable as it would require a completely new codec. I wish there was a progressive HDV codec that used all of the 25mb for video, but there isn't. It has been said that the extra 6mb/s is researved for pro audio. I don't know if the HD100 can use this or not.

[Wayne Morellini]

Originally Posted by Ken Hodson

Hey there Wayne. Been doing a lot of thinking for a guy who doesn't own a cam ;>)

Oh, I own a cam, just not one of these.

Thinking, not so much for a analysis/design scientific type, always considering multiple things at once, or in rapid succession. Solutions are easy enough for me (you wouldn't believe the amount of stuff I come up with) implementation when you get as sick as this is the problem.

If I had considered this when the JVC HD10 camera out (and the edge enhancement and saturation hack had been available) I would seriously had a different view on buying the HD10.


> As far as rigging something external to get 25p out of 30p, I think it would be very difficult. A software solution is

Difficult for most people, not very difficult for a skilled person in electronics/engineering. Finding one that wants to do it so everybody else can learn what to do, is the problem. But that is up to them to read this. I am just being courteous and passing along the idea, that people have wanted for so long (It might be easier then trying to decode/rewrite the firmware) for hardware people.

With only one reply, it looks like it might already be to late to find such a person, people might have already moved onto other cameras.


> better suited and has been done. JVC did a tech tour of the HD10 in Europe in the early days of the cam, demonstrating 30p to 25p conversion. Canopus was the software. I have never seen or attempted the conversion myself, but I will give it a try with a few software packages and report my results. I have read before that if you want 24p from 30p the best route is to first go to 25p then convert to 24p they way PAL users have been. 4% speed-up then adjust the audio pitch.

Yes, I suspect, that at the big FOV magnification required for good seat cinema viewing, it will look a lot worse then at normal TV distances. With this idea it might be possible to achieve perfect 25fps (or 24FPS) and the full 19Mb/s bit rate for extra compression quality.


> I'm very interested in the lens job. I know little about those type of lens. Are you saying the lens would provide full control? Lock the cam in the shutter you want, then the lens can be adjusted for the rest?

Yes, there are these sort of manufactured condenser based SLR adaptors out there for XL1 (years ago I found a earlier post where somebody mentioned his adaptor). But I have not studied the theory in detail myself yet.


> As far as your third want, 25mb/s, this is a little unfeasible as it would require a completely new codec. I

I'm not suggesting it, I was just saying that it is the other thing people would have liked to see, but this won't do it.


>It has been said that the extra 6mb/s is reserved for pro audio. I don't know if the HD100 can use this or not.[/QUOTE]

Yes, I would like to study this to find out just how much bandwidth advantage 1080 HDV has.

[Ken Hodson]

"Yes, I would like to study this to find out just how much bandwidth advantage 1080 HDV has."

For one, 1080i has no bandwidth advantage. Long discussed. 24p720 has a huge advantage over 1080i(more than 30p), due to its lower frame rate and it shows. But 720p30 with a 6GOP still holds its own ;>)
What would make you think 1080i held a bandwidth advantage?

"Oh, I own a cam, just not one of these."

Yes, gathered that. Hence my comment. I appreaciate all non cam owners jumping in.

"If I had considered this when the JVC HD10 camera out (and the edge enhancement and saturation hack had been available) I would seriously had a different view on buying the HD10."

The HD10 does not suffer from any over enhancement of EE, at least no more than any other HDV cam. I don't know what you mean by the "Saturation hack", but the colour reproduction of the HD10 has always been one of its strong points.

You brought up a lot of interesting points. I encourage further discussion. I would like to learn more about the lens adaptor, if it can really control exposure. Can a lens like this really have the amount of control like this?

Please keep posting, this forum needs some open minds, and new thoughts.

[Wayne Morellini]

Originally Posted by Ken Hodson

What would make you think 1080i held a bandwidth advantage?

I was questioning the usage/advantage of 25Mb/s HDV over 19Mb/s hdv, how much of that extra 6Mb/s gets used for video. Per pixel, though. there is no advantage, as there is less bandwidth per pixel (and other compromises).

"Yes, gathered that. Hence my comment. I appreciate all non cam owners jumping in."

Sorry, I thought you mistook what I said when you said "own a cam" rather than "own this cam".

"The HD10 does not suffer from any over enhancement of EE, at least no more than any other HDV cam. I don't know what you mean by the "Saturation hack""

Sorry, I understood that people had found how to change the edge enhancement and color saturation in the firmware, referenced in other threads here.

"You brought up a lot of interesting points. I encourage further discussion. I would like to learn more about the lens adaptor, if it can really control exposure. Can a lens like this really have the amount of control like this?"

It is how every multi-element lens system works, but to change the lens system to another format you need an extra element again. So yes, I don't know if you can do it that way, if you try to put it in front of the existing camera lens.

Please keep posting, this forum needs some open minds, and new thoughts.

I would semi love too (trying to take a break from the projects) but the forum is getting few posts and their doesn't seem to be the people about interested in it, like there was in times past. I am just sharing these ideas because there was a lot of interest here in these things in times past.

But one thing I think that people should look at, is too look at a condenser based lens adaptor (in front of the existing lens) to see if you can increase the amount of light without sacrificing the FOV. Normal rear projected lens adaptors loss too much light, where as what the HD1 needs is to extra light. With the XL1s one I heard of, it is so you can directly mount the Canon ES lens without zoom effect (I understand that most are just a hollow mounting adaptor) so there is no existing lens to stop you from fully using the manual controls of the SLR lens. I aim to do this for when I get a HD camera, I also would like to try other things ;).