Author Topic: Digital dolly - how to use properly?  (Read 838 times)

haeki

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Digital dolly - how to use properly?
« on: March 18, 2018, 09:12:28 PM »
Hi,

I am kind of able to use the digital dolly-feature, but for some reason it's not always reacting when I push the joystick. As well there is only one speed and it's only working horizontally. On the other hand it's not working over the full sensorrange, it's only using maybe half of the sensor for the dollymove. As I can't really find tutorial or documentation on how to use the feature I am asking here. Can anyone help?

I am on a 5D MK III with 1.1.3 and magiclantern-Nightly.2018Feb04.5D3113

Kind regards

a1ex

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Re: Digital dolly - how to use properly?
« Reply #1 on: March 18, 2018, 09:30:49 PM »
If you press the joystick multiple times, you can change the speed (though only in multiples of 8 pixels horizontally, or multiples or 2 vertically). Maybe that's why it doesn't react. Preview updates slowly, which can be confusing, but that's what we've got with our current knowledge about how LiveView works.

Modifying digital dolly to cover the full sensor is possible, but non-trivial (Canon recalibrates the vertical noise correction factors with each video mode reconfiguration, including when shifting the scanned area in x5 zoom mode). By default, Canon code scans a non-centered wide area in x5 zoom mode (3584x1320 usable area on 5D3) and moves it around as you move the focus box - notice a slight pause at certain positions on the screen, when it reconfigures the sensor.

You can, however, try something with the crop_rec_4k experimental build (caveat: requires fiddling)

- load crop_rec and mlv_lite
- set crop_rec preset to full-res LiveView
- reduce the vertical resolution in crop_rec submenu until you get the desired FPS (Target YRES = 1039 will give 23.973 FPS)
- recalibrate the CMOS[1] register to get good and centered image (trial and error)
- enable raw video and digital dolly - now it should cover the full width of the sensor.

If useful, I'll consider adding a full-width 1080p preset to crop_rec (maybe it can be pushed to about 5784x1080 at 23.976 FPS, or it might require slightly lower horizontal resolution).

Side note: the MLV spec also has metadata for 1-pixel increments for digital dolly, but would require special support from the MLV converter.

haeki

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Re: Digital dolly - how to use properly?
« Reply #2 on: March 18, 2018, 10:25:39 PM »
If you press the joystick multiple times, you can change the speed (though only in multiples of 8 pixels horizontally, or multiples or 2 vertically). Maybe that's why it doesn't react. Preview updates slowly, which can be confusing, but that's what we've got with our current knowledge about how LiveView works.

Modifying digital dolly to cover the full sensor is possible, but non-trivial (Canon recalibrates the vertical noise correction factors with each video mode reconfiguration, including when shifting the scanned area in x5 zoom mode). By default, Canon code scans a non-centered wide area in x5 zoom mode (3584x1320 usable area on 5D3) and moves it around as you move the focus box - notice a slight pause at certain positions on the screen, when it reconfigures the sensor.

You can, however, try something with the crop_rec_4k experimental build (caveat: requires fiddling)

- load crop_rec and mlv_lite
- set crop_rec preset to full-res LiveView
- reduce the vertical resolution in crop_rec submenu until you get the desired FPS (Target YRES = 1039 will give 23.973 FPS)
- recalibrate the CMOS[1] register to get good and centered image (trial and error)
- enable raw video and digital dolly - now it should cover the full width of the sensor.

If useful, I'll consider adding a full-width 1080p preset to crop_rec (maybe it can be pushed to about 5784x1080 at 23.976 FPS, or it might require slightly lower horizontal resolution).

Side note: the MLV spec also has metadata for 1-pixel increments for digital dolly, but would require special support from the MLV converter.

Hi Alex,

thank you for your extensive reply.I might try your suggestions mit crop_rec but for now I want to get the regular digital dolly to work correctly.

So 8px/frame would mean (3584-1920)/8/25 = 8,32seconds maximum or 4,8seconds for vertical movements, right? Is it possible to slow down the horizontal movement to 2px/frame as well? Because I just tested it and it seems like the vertical movement only has a duration of 3-4 seconds and the horizontal movement only around 6-7 seconds.

On the other hand I just figured out, that I always have to press the joystick to times to get it moving, but maybe that's normal.

Kind regards


a1ex

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Re: Digital dolly - how to use properly?
« Reply #3 on: March 18, 2018, 10:28:40 PM »
Sounds about right, considering the frame rate in 5x zoom is 30 by default.

Reducing the step size requires special support from the MLV converter (not even mlv_dump has this implemented), so it's not exactly a trivial change.

haeki

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Re: Digital dolly - how to use properly?
« Reply #4 on: March 18, 2018, 10:38:00 PM »
Sounds about right, considering the frame rate in 5x zoom is 30 by default.

Reducing the step size requires special support from the MLV converter (not even mlv_dump has this implemented), so it's not exactly a trivial change.

Ok, thanks for the info!