How To Dump Buffer Data Imagery??? - General Discussion and Assistance - CHDK Forum
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How To Dump Buffer Data Imagery???

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Offline blenderbach

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How To Dump Buffer Data Imagery???
« on: 01 / June / 2023, 17:57:31 »
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I checked this page on Frame Buffers, https://chdk.fandom.com/wiki/Frame_buffers , and I was wondering, is there any way to dump a frame from any of these frame buffers to the SD Card?

I want to see if I can attempt to dump a live view video from the movie buffer, or the viewport buffer. Maybe get a frame from certain buffers.

I've checked everything and haven't found any commands for CHDK on how to dump any Frame Buffer data? Any ideas? Thanks!
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Offline reyalp

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Re: How To Dump Buffer Data Imagery???
« Reply #1 on: 02 / June / 2023, 02:18:52 »
Quote from: blenderbach on 01 / June / 2023, 17:57:31
I checked this page on Frame Buffers, https://chdk.fandom.com/wiki/Frame_buffers , and I was wondering, is there any way to dump a frame from any of these frame buffers to the SD Card?
It's just a memory address, so you can use any of the normal file functions like write or fwrite from C code. This is how CHDK raw works.

There aren't Lua functions to write directly from memory to a file, but you can use eventprocs with call_event_proc or use call_func_ptr with addresses from stubs to access the same functions used in C.

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I want to see if I can attempt to dump a live view video from the movie buffer, or the viewport buffer. Maybe get a frame from certain buffers.
The screen dump module (see https://chdk.setepontos.com/index.php?topic=14347.msg146339#msg146339 and some related background https://chdk.setepontos.com/index.php?topic=14705.msg149375#msg149375) can be used to record the live view and UI buffers, and of course chdkptp can be used if you have a USB connection.

Note that this will *not* get you faster / higher res / better video than native video recording. Quite the opposite.
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Offline blenderbach

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Re: How To Dump Buffer Data Imagery???
« Reply #2 on: 02 / June / 2023, 03:45:07 »
Thanks for the information, but, I'm a bit confused.
Scripts in CHDK are always .LUA or .BAS

You mentioned "C"
What you're saying is for me to make my own CHDK build with extra C code for this.
You're definitely trying to send me to my grave. Joking, but that's a little too advanced for me. :P

Also, regarding the "eventprocs with call_event_proc or call_func_ptr", this does sound like it's much simpler. Could you please maybe give me a little explanation on this. I read through it, and it reminded me when I was debugging in a Commodore64, and I am known for causing CPU Halts, so, haha, I don't want to mess up my camera. I just need something in terms of context. I'm not exactly sure about the syntax, since there isn't a lot of documentation on CHDK, unfortunately, and I have to try guessing what something means. Thanks.
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Offline reyalp

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Re: How To Dump Buffer Data Imagery???
« Reply #3 on: 02 / June / 2023, 20:15:20 »
Quote from: blenderbach on 02 / June / 2023, 03:45:07
Thanks for the information, but, I'm a bit confused.
Scripts in CHDK are always .LUA or .BAS

You mentioned "C"
What you're saying is for me to make my own CHDK build with extra C code for this.
Yes. To do the same in Lua, you essentially have to understand the C functions, and then translate their usage to Lua. OTOH, if you use Lua you don't have to figure out how to build CHDK, or where to put your changes.

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Also, regarding the "eventprocs with call_event_proc or call_func_ptr", this does sound like it's much simpler. Could you please maybe give me a little explanation on this.
See https://chdk.fandom.com/wiki/Lua/Lua_Reference/Native_Function_Calls
You can find some an example in CHDK/SCRIPTS/TEST/tstcallf.lua

To write memory to a file, you could use the eventprocs Open, Write and Close (registered by SystemEventInit or System.Create, depending ont the camera). These functions generally behave similarly to the C functions described on https://pubs.opengroup.org/onlinepubs/009695399/functions/open.html (use the "See Also" links for write and close)

edit:
Note if you are using chdkptp, you can use the rmem command to dump camera memory directly to a file on your PC with the -f option, and of course, you can use lvdump and lvdumpimg to get the live view or UI buffers.
« Last Edit: 02 / June / 2023, 20:17:30 by reyalp »
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