5D Mark 2 onscreen audio meters - DSLR Hack development - CHDK Forum
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5D Mark 2 onscreen audio meters

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Offline hudson

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5D Mark 2 onscreen audio meters
« on: 25 / May / 2009, 08:48:59 »
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I found the VRAM pointer in the 5D Mark 2 and was able to write an onscreen audio meter.  It uses the calibration table in the ROM to determine the dB of the signal and has some very simplistic peak detection / ballistics.  More details at cinema5d.com, along with video of it in action.
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Offline PhyrePhoX

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Re: 5D Mark 2 onscreen audio meters
« Reply #1 on: 25 / May / 2009, 13:21:17 »
thats great stuff. so is this update permanent or do you do it like chdk, meaning hooking into the update process thus executing own code?
From your experience now, would you say is something like this (executing own code) portable to other canon dslrs?
How exactly did you do it? Congratz anyway :)
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Offline hudson

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Re: 5D Mark 2 onscreen audio meters
« Reply #2 on: 26 / May / 2009, 11:50:06 »
Quote from: PhyrePhoX on 25 / May / 2009, 13:21:17
thats great stuff. so is this update permanent or do you do it like chdk, meaning hooking into the update process thus executing own code?
It is almost exactly the same process as chdk; I was able to read chdk's boot-strap code for the SX10 to learn how it orchestrated the startup / reboot process from the firmware loader space (0x8000000) back into ROM space (0xFF800000).  My technique is a little different in that my loader does not contain any Canon code at all; rather than retype the assembly instructions in my boot loader, I have the loader copy 64 KB from 0xFF810000 to 0x50000 (just above the BSS) and make three careful pokes into this copy (init_task address, BSS size, and fixup two long calls).  It then jumps into it to let it do the hardware startup and "boot" DryOS.  One of the pokes changes the argument to create_task() from their init_task() to my_init_task() in my code.

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From your experience now, would you say is something like this (executing own code) portable to other canon dslrs?
I would expect that any of Canon's DryOS based DIGIC IV systems have very similar code.  It would still require mapping out the entry points for task creation, video memory, etc.  Hopefully they aren't too different!
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Offline PhyrePhoX

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Re: 5D Mark 2 onscreen audio meters
« Reply #3 on: 26 / May / 2009, 12:17:39 »
sounds great. btw are you aware of the fact that it should be quite easy for you now to code an audio-trap? a shot will be triggered if a certain treshold is reached, for example a loud bang, or an animal in the night shuffling along, or whatever.
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Offline hudson

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Re: 5D Mark 2 onscreen audio meters
« Reply #4 on: 26 / May / 2009, 13:19:09 »
Quote from: PhyrePhoX on 26 / May / 2009, 12:17:39
btw are you aware of the fact that it should be quite easy for you now to code an audio-trap? a shot will be triggered if a certain treshold is reached, for example a loud bang, or an animal in the night shuffling along, or whatever.
That's a great idea.  And should be trivial once I find the "take the picture" function.  I also need to find the iso/shutter/aperture functions; that is the near-term end goal of this work: manual control of the those parameters while filming in video mode.
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Offline PhyrePhoX

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Re: 5D Mark 2 onscreen audio meters
« Reply #5 on: 26 / May / 2009, 18:31:59 »
yeah, that'd be great. and once you find those things and release something, it will be "easier" for other hackers to find the rest, like vitalyb laid the groundwork of chdk and the community built the rest around it and made it what it is today. btw you got a pm ;)
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