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PTP Extension on the S95

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PTP Extension on the S95
« on: 18 / August / 2011, 15:12:43 »
Hi, I would like to know if anyone has experience with doing remote capture and download from a Linux PC with the S95. I've got ptpcam and have been tinkering with that, but when I try "ptpcam -c" I get the response:

Initiating captue...
Your camera does not support InitiateCapture operation!
Sorry, blame the Canon Inc.!

I downloaded the source for chdkptp but I'm getting compile errors when trying to build that.

Ultimately, I just need to control this S95 (remote capture and download, primarily) from a Linux-based computer over USB. Can anyone suggest a good solution to this or at least point me in the right direction?


Offline reyalp

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Re: PTP Extension on the S95
« Reply #1 on: 19 / August / 2011, 00:02:41 »
You need to use the CHDK modified version of ptpcam to interact with the CHDK PTP protocol. The command you are trying to use is a regular ptpcam command, which doesn't known anything about the CHDK extension.

All CHDK commands are accessed with the --chdk option if you are using the modified ptpcam.

You can find the source at

I replied to your post regarding errors building chdkptp.
Don't forget what the H stands for.

Re: PTP Extension on the S95
« Reply #2 on: 23 / August / 2011, 16:43:58 »
Ok, I found the --chdk option and have been playing around with that. One thing that is weird, though, is that when I change the mode on my S95 by using "mode 1" it gives me an error:

<conn> mode 1
*** stack smashing detected ***: ./ptpcam terminated
======= Backtrace: =========
======= Memory map: ========
... (shows the contents of memory)

The really strange thing is that the camera goes into recording mode just fine and if I restart ptpcam with the --chdk option, it connects just fine, too and I can start snapping pictures. I looked up what "stack smashing" is and it turns out to be some gcc built-in protection against buffer overflow errors. When I built ptpcam with the option -fno-stack-protection I didn't get that error anymore when switching modes. Does anyone know why it does that?


Offline reyalp

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Re: PTP Extension on the S95
« Reply #3 on: 24 / August / 2011, 01:14:10 »
It's a bug. The buffer used by ptp_chdk_switch_mode was too small for the string...

Should be fixed in chdkde  r776
Don't forget what the H stands for.


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