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CHDK PTP multiple instances

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Offline reyalp

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Re: CHDK PTP multiple instances
« Reply #30 on: 16 / September / 2013, 13:20:39 »
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1 - try to solder some optocoupler adressed by one or two Arduinos that disconnect/reconnect the cameras from the USB-Remote-Cable/Usb-Hubs to be able to switch between USB-Remote/PTP

2 - wait a little because the things you discuss here will maybe provide a solution that makes special hardware unnecessary?

The last bit of discussion is on ways to switch between PTP and USB remote on the camera side, it would not remove the need for special hardware on the other end.

To get precision sync, you need to use the USB remote method, toggling the +5v line. To transfer over PTP, you need a full USB connection. Unless your host (and the downstream hubs) have software control of the +5v line, that means special hardware.

The only way around this would be to use something other than USB power for signaling. There was some discussion here of using the battery temp sensor as an input instead: http://chdk.setepontos.com/index.php?topic=10385.0
Assuming that could be done with acceptable latency (unknown) that would allow you to use normal USB all the time. It would require some modification to the CHDK code, to monitor GetAdChValue rather than USB power.
Don't forget what the H stands for.

Re: CHDK PTP multiple instances
« Reply #31 on: 17 / September / 2013, 04:26:21 »
Nevertheless I am unsure how to go on with my camera rig.
What would you propose? Should I:

2 - wait a little because the things you discuss here will maybe provide a solution that makes special hardware unnecessary?
Martin,

About Your "50-camera" rig and setup

Camera Alignment.

Do you have a camera alignment procedure, such as calibration target, at the cameras focal point.

i.e. PingPong, Golf or Tenis balls mounted on a fishing line.

Do you have a camera software calibration procedure.

i.e. Hugin's latest "Align Image Stack" or some thing similar, that provides for sub-pixel image alignments.

Rig & Setup

1/ A Multi-Camera sync cable has no length limits, but a longer sync cable is more likley
   to have RF and Noise pickup problems that will affect the camera sync. (i.e. use RF supression Ferrites)

2/ If the Multi-Camera sync cable is a also a "USB" cable there is a, USB, length limit of about 5 meters.
   There is also a limit of about three USB-Hubs in series.

3/ So if you are using 10 port USB-Hubs you would need 5 NoteBooks. And if you look at photos of other Multi-Cam rigs they usualy have quite a few notebooks as part of the rigs.

4/ Some Multi-Port Hubs are easy to modify in regard to switching the 5 volt power supply (syncing) and then fully "Discharge" the 5 volt supply via a suitable termination resistor.

5/ However you have to be aware of a another potential problem, that in a "Standard" Sync USB cable there is no "Discharge" path, except for the camera's internal non linear circuits.
   This has been a subject in several previous posts and dosn't appear to be a problem with twined cameras but could be major problem with your rig that has a combination of long USB cables and 50 cameras.

6/ An Idea I am currently working on (for a Multi-Cam rig) is boot the NoteBooks, or Oblsete computers, from a CdRom all the windows software then runs in RAM. This has been tested on, and works relaibly with, Xp and windows-Blue.

7/ While this may, at first, seem complicated in practice its not as there are various example projects which you can download and easily customise to your needs.

8/ There are several advantages to this aproach with multi-cam rigs such as reliability, repeatability, and dependability, as each  NoteBook is runing the same software so project management, software modification and up-grades are all very easy.

9/ Also it is posible to have an absolute software path to each camera (via "Merging") where by each camera is customised and allocaded it's own ID which also makes camera management and image downloading much easier.

10/ Normaly the Canon cameras are "Installed" which is a "Random" process which is then combined with many other "Random" windows processes.  Also windows allocates a "Weight" to the "Instalation" of the cameras so this mess/combination can easily become un-stable and un-reliable.

11/ Another Idea I am working on is a new faster (x10,000) and more flexible method for syncing a Multi-Cam rig. It is interesting to note that  windows-Blue, a "Preview" is free to download, and has built-in support for this concept.

12/ A customised CHDK build can improve the overall performance of both PtpCamGui and ChdkPtp so this is a option to save image procesing time.

H-H

Happy Hacking   

Continued ...
« Last Edit: 18 / September / 2013, 04:39:02 by Hardware_Hacker »

Re: CHDK PTP multiple instances
« Reply #32 on: 17 / September / 2013, 04:47:28 »
Continued.... from post 31
« Last Edit: 17 / September / 2013, 04:49:03 by Hardware_Hacker »

Re: CHDK PTP multiple instances
« Reply #33 on: 17 / September / 2013, 04:50:39 »
continued ..... from post 32

This shows how the "Merged" cameras behave under Xp and Win-Blue.

The "Merged" cameras always have a known and absolute path.

So windows "Registry" is a massive "Data Dase" which can be accessed
to recover the absolute camera path and the cameras "ID"

This seems to work well for me.

H-H

« Last Edit: 18 / September / 2013, 04:47:39 by Hardware_Hacker »


Re: CHDK PTP multiple instances
« Reply #34 on: 17 / September / 2013, 05:19:00 »
Continued.....from Post 33

Its simple,

Dont use "Auto" modes

and

Dont use "Smart" modes

to improve camera performance, may be, the "Auto's" and "Smart's"
"Tasks" could be suspended.

I seem to recall a Magic Lantern post about this (???)

H-H
« Last Edit: 18 / September / 2013, 04:53:13 by Hardware_Hacker »

Re: CHDK PTP multiple instances
« Reply #35 on: 17 / September / 2013, 05:25:52 »
Hello H-H, thanks for you mail. I don´t understand the purpose of your colorful pictures.

As far as I understood there is, at the moment, no reliable way to fire the cams synchronized via USB. It seems to me, one has to switch between a usb-remote and chdkptp. But nevertheless I wonder what you are doing with your Windows Blue, are you pairing USB devices?

Best regards. Martin

Re: CHDK PTP multiple instances
« Reply #36 on: 17 / September / 2013, 10:07:27 »

Rig & Setup

1/ A Multi-Camera sync cable has no length limits, but a longer sync cable is more likley
   to have RF and Noise pickup problems that will affect the camera sync. (i.e. use RF supression Ferrites)

2/ If the Multi-Camera sync cable is a also a "USB" cable there is a, USB, length limit of about 5 meters.
   There is also a limit of about three USB-Hubs in series.

3/ So if you are using 10 port USB-Hubs you would need 5 NoteBooks. And if you look at photos of other Multi-Cam rigs they usualy have quite a few notebooks as part of the rigs.

4/ Some Multi-Port Hubs are easy to modify in regard to switching the 5 volt power supply (syncing) and then fully "Discharg" the 5 volt supply via a suitable termination resistor.

5/ However you have to be aware of a another potential problem, that in a "Standard" Sync USB cable there is no "Discharge" path, except for the camera's internal non linear circuits.
   This has been a subject in several previous posts and dosn't appear to be a problem with twined cameras but could be major problem with your rig that has a combination of long USB cables and 50 cameras.

6/ An Idea I am currently working on (for a Multi-Cam rig) is boot the NoteBooks, or Oblsete computers, from a CdRom all the windows software then runs in RAM. This has been tested on, and works relaibly with, Xp and windows-Blue.

etc...


This is a very interesting thread - thanks for this Hardware_Hacker.

Based on some of your notes I guess my primary school picture, attached, is not a particularly sound basis to meditate upon ?  :blink:
« Last Edit: 17 / September / 2013, 11:03:33 by andrew.stephens.754365 »

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Offline reyalp

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Re: CHDK PTP multiple instances
« Reply #37 on: 17 / September / 2013, 13:44:37 »
Hello H-H, thanks for you mail. I don´t understand the purpose of your colorful pictures.
You are not alone in this :blink:
Don't forget what the H stands for.


Re: CHDK PTP multiple instances
« Reply #38 on: 17 / September / 2013, 16:15:18 »
So when the script wants to allow PTP, it sets the USB bit in physw_status on, while leaving remote enabled? As long as the shooting is initiated by script, this seems like it should be OK.

Apologies, i'm trying to follow / work out what is what - does the 'USB bit in physw_status' referred to above equate to the:

"USB setup status" referred to by waterwingz here:

http://chdk.setepontos.com/index.php?topic=10687.msg105256#msg105256

"When you have USB remote shooting and remote sync enabled, the shooting sequence "stops" just before the shutter actually opens if the USB power = 5V.   It waits there for the USB power to go to 0v. When that happens, it completes the shot.  It does not care how you got to that point in the shooting sequence (shutter button or USB switch or script) - it just looks at the 5V line and USB setup status."

?
« Last Edit: 17 / September / 2013, 16:19:56 by andrew.stephens.754365 »

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Offline reyalp

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Re: CHDK PTP multiple instances
« Reply #39 on: 17 / September / 2013, 17:03:05 »
Apologies, i'm trying to follow / work out what is what - does the 'USB bit in physw_status' referred to above equate to the:
physw_status is a variable (array of 3 32 bit words) in the canon firmware that contains bits for the status of various hardware. Look in your platforms kbd.c to see how it is used.

CHDK overrides the task (PhySw task in Canon, kbd_task in chdk) that reads the hardware state into physw_status for the rest of the firmware. This allows us to have the real state, and but make the canon firmware think it has a different state. This is the basis of all the script keyboard functions, alt mode keyboard, sd lock override, usb remote etc.

usb remote has the additional feature that it can read the USB bit directly from hardware on demand, which is what the following refers to:
Quote
"USB setup status" referred to by waterwingz here:

http://chdk.setepontos.com/index.php?topic=10687.msg105256#msg105256

"When you have USB remote shooting and remote sync enabled, the shooting sequence "stops" just before the shutter actually opens if the USB power = 5V.   It waits there for the USB power to go to 0v. When that happens, it completes the shot.  It does not care how you got to that point in the shooting sequence (shutter button or USB switch or script) - it just looks at the 5V line and USB setup status."
Don't forget what the H stands for.

 

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