Anamorphic setting for MJPEG VGA mode in PTool 3.55d

LPowell

Congratulations to Vitaliy, not only for cracking the v1.34 firmware with PTool 3.55d, but for the new patches that enable modification of both frame size and quality settings in the GH1's MJPEG VGA mode. This video mode's standard frame size is 640x480, equivalent to NTSC SD resolution. With PTool 3.55d, this frame size can be patched to any dimensions up to 1920x1080. However, the VGA mode's SD-resolution 4:3 aspect ratio still applies to the patched dimensions. If you actually set a 1920x1080 frame, it would be horizontally squeezed into a 1440x1080 aspect ratio, which is an anamorphic ratio of 1.33X. If you used this frame size with a 1.33X anamorphic adapter, such the Panasonic LA7200, it would produce a 1920x1080 video frame in the correct aspect ratio in MJPEG VGA mode. While this may seem redundant, it's one way to produce anamorphic bokeh and flares in FHD resolution (though of course it would still be recorded at MJPEG's 30fps).

An even more interesting application of the new VGA mode is using it to support shooting with 2X anamorphic adapters. In the GH1's 16:9 HD mode, these lenses would produce an excessively wide frame size of 2560x720. Setting the 3:2 VGA mode to 1920x720 produces the perfect anamorphic ratio for use with 2X anamorphic lenses. These videos can be viewed straight out of the camera in the correct aspect ratio, with no need for post-processing.

For those who'd like to try this new 2X anamorphic mode, I recommend patching the VGA mode quality settings with the values used in my MJPEG Anamorphic Cinemascope Patch. I've gotten reliable results from these settings at a frame size of 1920x810 in HD mode (with 1.33X anamorphic lenses), and they appear to work just as well at 1920x720 in VGA mode in PTool 3.55d. Here is a list of the patch settings, which can be appended to existing INI files, or entered directly into PTool in the Patches for Testers/MJPEG Movie Mode section:

480p30 width=1920
480p30 height=720
F1 Quality=280
F1 Table=4
F2 Quality=250
F2 Table=10
F3 Quality=225
F3 Table=24
F4 Quality=200
F4 Table=48

Vitaliy_Kiselev

You can also look at new (some of them ahd been in early versions) AVCHD related patches.
As looking at GH2 code I introduced them again.
I do not think that they could greatly affect compression, but could help with spanning problems and stability.

CRFilms

@LPowell I recently found a 2x lens I bought a few years ago, and would the new settings you listed need croping down to 2:35:1 area or would it give the proper ratio?

CRFilms

I made a thread in the dvxuser forums asking about 2x adapters and my math was all wrong. I was multiplying height and width. 1280 x 2 = x960 winds up equaling out to I just did a quick test 1280 x 960 worked. It recorded using these settings:

480p30 width=1280
480p30 height=960
F1 Quality=280
F1 Table=4
F2 Quality=250
F2 Table=10
F3 Quality=225
F3 Table=24
F4 Quality=200
F4 Table=48

I can't do a real vid because my 2x lens doesn't have any adapters and I just held it up by hand and it was beyond shaky. If somebody has a 2x lens that's properly mounted to their cam could you do a test with that setting and see how it looks?

This is one of the best screen grabs I could get:

EDIT: 960 gives a 2.66 ratio. For 2.35 you'd need 1090, don't know if that would record though.

CRFilms

I just tried 1280x1060 and it didn't work. It recorded, but Sony Vegas wouldn't read the file. I had to convert it to a WMV with windows movie maker and even then it was still a bit off. I'll try 1000 next see how that looks.

EDIT: 1280 x 1000 works. Now I just need to get/build a mount so I can use the 2x lens I have.

CRFilms

OK, last post... @LPowell is right with his settings. He mentioned this in the original Anamorphic thread on dvxuser....when the camera records 1920 by 720, it's not just cropping the standard image, it warps it also. I just did a test and everything looked way fat. I then put the 2x lens on and the shot looked normal. I had to see it myself to truly get it.

1920 x 720 it is.

johnnym

Simple math really.

Thanks for the settings LPowell. Quality seems fine. When trying 1440x1080 i get constant failures though. So the only reliable patch seems 1920x720.

I forgot how much sharper AVCHD is on the GH1, now when shooting MJPEG again.

Would anyone think there's a real benefit shooting at resolutions higher than 1280x720?

LPowell

The benefit to shooting in the correct anamorphic ratio is that the camera produces the 1920x720 frame directly from the 12-bit color data output from the image sensor. This is done before the image is converted to 8-bit, 4:2:0 YCC color data and compressed into MJPEG format. This produces higher quality images than stretching a 1280x720 MJPEG compressed frame would in post.

For a 2X anamorphic adapter, the ideal frame size for widescreen cinemascope would actually be 2160x810, which is a screen aspect ratio of 2.67:1. Cropping this down to 1920x810 would produce a 2.37:1 screen aspect ratio and eliminate any vignetting on the far edges of the frame. With early versions of PTool, I was able to patch the GH1 to produce stable videos at 2160x810. Perhaps Vitaliy may be able to increase the maximum width setting of the VGA frame to support this 2X anamorphic frame size in PTool 3.55d?

kikis

@lpowell

have you tried a stable version of 2160x810 successfully in VGA mode yet?

LPowell

@kikis The maximum MJPEG width in PTool is currently 1920 pixels.

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