How to build the ultimate camera trigger - Hotwire! Hardware Mods, Accessories and Insights - CHDK Forum
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How to build the ultimate camera trigger

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Offline ahull

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How to build the ultimate camera trigger
« on: 16 / November / 2014, 07:27:49 »
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This has little to do with CHDK, but I was so impressed with the construction details I had to share it.

https://www.youtube.com/watch?v=E2Czay6RSNM

I first spotted it and re-posted from HAD

http://hackaday.com/2014/11/16/100-diy-intervalometer-is-100-awesome/#comments
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Offline fabri22

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Re: How to build the ultimate camera trigger
« Reply #1 on: 16 / November / 2014, 09:30:50 »
hmmm. Are you studying how to transform a dynamite battery into a neutronic bomb ?  :)

Don't know how to define the project you posted: impressive or crazy.
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Offline waterwingz

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Re: How to build the ultimate camera trigger
« Reply #2 on: 16 / November / 2014, 09:51:33 »
A nice project. But the only thing you can do with his new toy that CHDK cannot also do is trigger on sound.  I believe all Canon P&S have microphones built-in (for video recording) so that seems like something that could be done as well.  I'm a bit surprised somebody has not done so already.
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Offline ahull

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Re: How to build the ultimate camera trigger
« Reply #3 on: 16 / November / 2014, 17:03:28 »
Sound triggering sounds interesting  :D

I'm not sure how we would go about it however. There are a number of "Sound" related strings in the PRIMARY.BIN dumps I have, so presumably it would be a case of trawling through the strings and assembler dump to try and figure out how to "listen", while at the same time effectively pumping the audio in to the VxWorks or DryOs equivalent of /dev/null or perhaps a ring buffer. 

If we can figure out how to do this, we would also have the slightly simpler job (possibly) of triggering on a particular sound related event (perhaps by using a bit of software defined hi/low pass filtering or FFT analysis).

Its probably "doable", assuming the Digic/hardware exposes the audio stream in some way, rather than simply pumping it in to the video stream.

I presume the audio must be available separately from the video stream,  as some Canon cameras have an audio "memo" feature.

In other words, I'm not sure how deep this particular rabbit hole is likely to get, but it does sound like an interesting rabbit hole to explore.

Access to the audio stream and hardware might also give us the ability to provide some of the sort of audio features that are available in Magic Lantern. (AGC control, audio level control, VU meters and so forth).
« Last Edit: 16 / November / 2014, 17:08:39 by ahull »
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Offline srsa_4c

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Re: How to build the ultimate camera trigger
« Reply #4 on: 16 / November / 2014, 17:42:13 »
Quote from: ahull on 16 / November / 2014, 17:03:28
Sound triggering sounds interesting  :D
Indeed. I seem to recall some old cameras have their audio A/D running all the time, simply reading the appropriate DIGIC MMIO (above 0xc0900000) gave the current A/D value. However, this method is only possible on cameras which use the DIGIC's built-in A/D converter (these can only record sound at 11kHz/8bit). New cameras use external codecs, activating audio and getting the samples is presumably much more complicated on them.

I'd like to note that most "devices" are not implemented as devices of the OS, so /dev/null is not available for them (and the cameras' DryOS seems to lack a /dev/null implementation anyway).

Quote
In other words, I'm not sure how deep this particular rabbit hole is likely to get, but it does sound like an interesting rabbit hole to explore.
I agree, but unfortunately the cameras are full of similar rabbit holes and somebody has to maintain CHDK too  :(
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Offline waterwingz

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Re: How to build the ultimate camera trigger
« Reply #5 on: 16 / November / 2014, 19:55:53 »
Quote from: srsa_4c on 16 / November / 2014, 17:42:13
I agree, but unfortunately the cameras are full of similar rabbit holes and somebody has to maintain CHDK too  :(
Agreed - just fixing what is already there but doesn't really work all the time is pretty all consuming.

Still, it's been a while since we added any big new feature that the average newbie might use (other than precision sync and video sync - which seems to have been appropriated somewhere else without credit given - again).

Might be a fun addition if it's actually possible to do.


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Offline philmoz

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Re: How to build the ultimate camera trigger
« Reply #6 on: 16 / November / 2014, 20:23:40 »
Quote from: waterwingz on 16 / November / 2014, 19:55:53
Quote from: srsa_4c on 16 / November / 2014, 17:42:13
I agree, but unfortunately the cameras are full of similar rabbit holes and somebody has to maintain CHDK too  :(
Agreed - just fixing what is already there but doesn't really work all the time is pretty all consuming.

Still, it's been a while since we added any big new feature that the average newbie might use (other than precision sync and video sync - which seems to have been appropriated somewhere else without credit given - again).

Might be a fun addition if it's actually possible to do.

There's an audio trigger in Magic Lantern for Canon DSLR cameras - might be some clues there that could help.

Phil.
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Offline thepanoguy

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Re: How to build the ultimate camera trigger
« Reply #7 on: 16 / November / 2014, 22:06:13 »
Another approach is a voice operated switch (VOX).

http://en.wikipedia.org/wiki/Voice-operated_switch

http://www.electronickits.com/kit/complete/elec/k126.pdf

I built the above circuit about 4 years ago, it worked well as a USB trigger device.

The sensitivity is dependent on the microphone.

My lifestyle changed, I did not carry out extensive field testing.
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Offline ahull

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Re: How to build the ultimate camera trigger
« Reply #8 on: 17 / November / 2014, 09:21:52 »
Quote from: thepanoguy on 16 / November / 2014, 22:06:13
Another approach is a voice operated switch (VOX)....

Indeed, and ebay is awash with sound activated gadgets, some of which could be re-purposed. I suspect there will also be an Android/iPhone app for it too (probably several).

If CHDK could manage the task, however,  there would be no additional hardware requirements. I already have a large collection of weird and wonderful stuff in my photography clutter, but since the camera already has a microphone, the idea was to use that somehow as a trigger.
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Offline thepanoguy

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Re: How to build the ultimate camera trigger
« Reply #9 on: 17 / November / 2014, 15:10:00 »
@ ahull,

I agree. I am a hardware guy; useless at software. The developers are overworked, imposing on their valuable time is not my style. I just posted the information in case someone wanted to experiment.

The issue I found with the circuit was the microphone bandwidth was still too wide. The vox would still false trigger. You would need to make some sort of cover to make the camera microphone directional.
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