4:4:4 12-bit Uncompressed DVX100

[Stephen Birdsong]

I just finished reading all the posts, took me a long time to get caught up.

Juan, just wanted to commend you for pushing the envelope, its great to see how much progress you've made.

I think its a real testement to the spirit of indie filmmakers, that we will make the best out of what we have to work with.

Users of the DVX100 might finally get what they actually paid for if your mod is successful.

Im an Xl1s owner and even though this mod probably wouldnt be functional for the xl1s, I'm still thrilled to see the results you've gotten from a 1/3in 3chipper. Coupled with some sort of 35 adapter, these cameras will have latitude and depth of field comparable to 35mm or HD. Impressive. The lense options for the Xl1s have suddenly become overshadowed by the potential of your mod. I want a DVX100 now.

Wish I could contribute, it seems like everything has progressed to a point where I could be of no service.

The green screen:
it may be better to find a green posterboard, in my experience, it is harder to find a uniform blue than it is to find a uniform green. Light the greenscreen as evenly as possible, but not too bright, as you dont want to bounce any of the color onto the subject.
Suggestion: put the camera in the corner. Direct the worklight into the corner/ceiling. This should create enough soft light to illuminate both the subject and the greenscreen. Use your second worklight to create a rim, by directing the lamp at the backside of the subject.

If that is not enough light, here is a more complicated suggestion:
use the same worklight to bounce into the corner/ceiling.
use the second light as a key light on the subject about 45 degrees off camera. Use something (like the white side of your blue screen posterboard) to bounce the light from the second light directly back at the subject. what this will do is use the key light also as the rim light. Remember, the angle of incidence equals the angle of reflection.

Also, mirrors are a great way to increase the light level in a room.

Stephen Birdsong

[Thomas Smet]

Just trying to figure out this channel issue.

A quick question for Juan.

does the image of the raw image actually have a larger fov or are there just more pixels that represent the same area. I assumed it was actually a wider view and then the camera just crops the image.

If that is the case do you know how the image is being cropped? Does it just take 360 left and right of the center and then 240 top and bottom from the center. This may help figure out what is going on with the image.

I agree that we need a perfect raw frame and dv frame to figure out exactly what the dvx100 is doing to the image. How about using the remote control to hit the record button that way you wouldn't nudge the camera. I also say ditch the rez chart and shoot something with finer detail. What I suggest is making your own chart to test the alignment. Creat a series of one pixel width lines that form cross shapes. Stick them in each corner, then some more centered between those, and finally one in the exact center. Print this out on white paper at the highest rez you can do. This will give us only the details we need to figure out for the alignment. The rez chart can be a little messy to try to match up pixels because the lines are too thick and soft. Having the thin cross shapes at the edges corners and center will allow us to figure out the offset on each side.

I think we should figure out how the dv image is cropped first. We should then crop the raw image in the same way so we can compare the dv to the raw frame with better results.

[Randall Larsen]

Its probably a rehash of our previous discussions on FAT32 etc. but I found this discussion on Slashdot informative:

http://ask.slashdot.org/askslashdot/.../2211230.shtml

FAT32 seems to be the only systems readable on all 3 commonly used O/S. The question is raised: what file formating tools exist to format larger than 40gb FAT32 partitions. Some disks come preformatted in FAT32 with much larger partitions. How do we format (or reformat disks) with large Fat32 partitions.

[Randall Larsen]

There is according to the discussion on slashdot a $40 tool from Paragon that allows you to mount ext3 files everywhere. ext3 has advantages over FAT32 so maybe Juan should consider ext3.

see the august 13th post of Dougmc.

Not sure whether Paragon allows read and right of xfs from windows.

Paragon's Mount Everything [mount-everything.com] also Ext2fs Everywhere [ext2fs-anywhere.com]

There is another tool that allows reiserfs from windows.

The main objection to FAT32 (in the long run) is that since its not
a jounaling file system. There is a good chance a power outage or a tripped over firewire could cause data to be lost. Other objections to FAT32 are mentioned in the Slashdot discussion.


I add that the max 4gigabyte -2 bytes file size could be a problem with long takes if all the frames go in one pile.

You can make large fs32 disks from Windows Xp from the command line interface: format d: /fs:f32 So thats not a big problem.

[Jason Rodriguez]

Doesn't work on a mac though :-(

[Juan P. Pertierra]

I just connected the joystick again, and took off the letterbox, I also set the pedestal back to 0, since all the other options where netural as well.

I'm going to go and find green poster board right now, if I'm lucky I can do some new tests tonight.

Also, does my current lighting work? I have two yellow work lights from wal-mart :P

The best I can do is make sure they have the exact same type of bulb in them?

Juan

[Stephen Birdsong]

just white balance to those lights, try to make your subject and your greenscreen evenly lit. You dont want too much light on the green screen, as it will bounce onto the subject, giving them a rim of green, which makes for a piss poor key. But, like someone said earlier in the thread, it doesnt need to be pretty..

stephen

[Juan P. Pertierra]

Ok, i got two new posterboards. One is blue, which is clearly much brighter than the one i used before, it looks to be actual flat blue. The other one is green, but it looks kinda flourescent so i'm not really sure. I'll try both.

I'll be sure to grab DV stills as well.

Juan

[Juan P. Pertierra]

Ok, someone post a simple description of doing the keying in photoshop CS. Should I do it with separate R,G,B layers or with all the layers together? I'm currently using 'Select Color range", but i'm not sure if i'm doing it right.

Juan

[Randall Larsen]

Jason,

Well maybe something can be done with ext3 on Mac OSX. You might recall that OSX is a flavor of BSD. Free BSD has tools for reading Ext3 so tools have also been created for Mac OSX. See the following urls:

MAC OSX:
http://www.versiontracker.com/dyn/mo.../macosx/ 18619

This tool works with OSX 10.2 and later. According to the site it supports reading, writing, and formating, both hard disks and recordable cdroms.

EXT3 Linux and Windows:
http://www.ibiblio.org/mdw/HOWTO/Fil...-HOWTO -6.html

http://www.it.fht-esslingen.de/~zimm...re/ ltools.htm

suggested by nsrbrake on slashdot.

[Juan P. Pertierra]

New bluescreen test
~~~~~~~~~~~~

Ok, i followed the same procedure as before, but this time I used the bright blue screen. Here is the photoshop file for the RAW R,G,B layers, uncorrected & unaligned:

http://expert.cc.purdue.edu/~pertierr/blue0.psd

In addition to the traditional 10-bit handicap, something was causing a hefty amount of noise so take that into consideration. This is my 'try' to isolate the object:

http://expert.cc.purdue.edu/~pertierr/blue0.tif

Now, i'd like to hear specifically what looks wrong so I can try and fix that. I'm not sure how good the isolation has to be, but at least this time I didn't get the letters! <g>

Finally, here is the DV frame for the EXACT SAME SCENE AND SETTINGS. Why capital letters? You'll understand when you see it. This is only a few frames apart from the RAW frame, and i took care not to bump the camera.

http://expert.cc.purdue.edu/~pertierr/blue0_DV.tif

It's painful to look at. Basically this is what happens when you put the RAW data above through the camera circuitry and get it off the DV port or DV tape.

[Jason Rodriguez]

Actually it only supports Ext2, but I'm thinking that the only difference between the two filesystems is journaling, so they should be pretty compatible with each other, no?

Either way, I'd say that Ext2 is probably the best bet then, because everybody can mount it, and it's a modern filesystem that won't give us the space problems that FAT32 confines us to.

[John Cabrera]

So this is just rough... but I can say for sure that the height of 492 is actually not compressed at all as I had originally thought. full hoz res stays in tact, but is cropped mostly on the bottom and a bit on the top. Widthwise the image needs to be compressed roughly 94.7% in order for it to match up with the DV... with that squeeze, it ends up with a rez of 730... ten extra pixels... not much, but not bad. especially since a few pixels on the right of the DV are blacked out and are not so on the RAW. Those 10 pixels in question are cropped only on the right side of the frame. And the entire image seems to be shifted over exatly the number of black pixels on the left. Pretty interesting stuff. THis is getting closer to figuring out what the camera is actually doing to the image as it converts it to DV... looks like there's a bit of cropping as well as a bit of compressing in order for it to fit into the 720 x 480 DV standard.

As for the channel problem, this grab isn't really a good one for that. The DV is so clipped and since the only detail exisits in the middle of the frame it's hard to do the comparison. The channel test would be much better suited to an image like the one of your cat, the couch, and the TV (and you of course in the background). An image with a dense composition and detail all the way across the frame. We'd need both a DV grab and a RAW, of course.

That flourescent Green posterboard you bought is exactly what you should be using for this greenscreen test. Those drugstore flou green poster boards are perfect for green screen work. We used some on a film I directed last summer and they worked as good as the green screen stage we rented earlier in the shoot. Also, I'm curious to see how the camera handles that saturated of a green.

John

[Juan P. Pertierra]

isn't the horizontal compression you are doing just due to the aspect ratio? I still get a perfect image when i apply the NTSC aspect ratio. You still get the 773 pixel resolution, they are just not square sensor elements.

I will do some tests using the green board tomorrow, and post the results. If you have any other suggestions let me know...I will try to setup a darker scene this time...i thought i did but then i look at the DV footage and it's all clipped.

Juan

[Randall Larsen]

Yes you are correct I believe that with this application the mac mounts ext3 as ext2 (no journaling). Perhaps someone is working on this though.

Its up to Juan what file system he wants to use. I think there is a strong case for Ext3/Ext2. Its the logical choice.

However, as we saw in the case of VHS vs. Beta the market will sometimes choose a system because its ubiquitous and "open" rather than the best solution available.

The system chosen by the market or by market leaders is not always technologically superior.

The bottom line is that Juan wants to sell his mod. If Juan goes the logical route, people who buy the mod may not understand why ext3/ext2 was chosen.

Users might prefer ext3/ext2 when they actually go to use the mod; however, in choosing to buy they might not understand why a Linux file system was chosen when they want to download the files on Windows and Mac only.

However, a file system that is likely to fail (fat32) cannot be good for long term sales. So perhaps the use of ext3/ext2 has to be sold as a feature and not an unecessary complication. One also has to worry whether the application that allows MAC OSX to read ext2 files will be maintained in future versions of MAC OSX.

The rumour is that Apple is prepared to make LINUX a part of their business plan if that ever makes sense for them. OSX is partly an effort to position themselves to be able to port Linux applications easily. Its not so easy to port linux appliations to windows.