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Shooting while transferring over USB

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Offline Karmaschinken

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Re: Shooting while transferring over USB
« Reply #10 on: 20 / December / 2013, 10:56:42 »
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Well, I have 5 Eye-Fi cards and one Fritz-Box, and what I can say is that it is far too slow and unreliable. Sometimes one has to wait minutes until the JPGs arrive. If I wanted to shot RAW, it would be even slower.

If I could make the SD-USB-Card run I suppose to have both fast, parallel and reliable down and upload to a lot of cameras. Also it would be easy to use them together with some Rasperrys which are then connected via Network adapter. If I could hook up 10*5 cameras to let's say 5 Raspberrys with that technique, I would achieve almost immediate download. :-)

Do you think  reyalp or srsa_4c are watching this thread?  8)
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Offline srsa_4c

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Re: Shooting while transferring over USB
« Reply #11 on: 20 / December / 2013, 11:05:59 »
Quote from: Karmaschinken on 20 / December / 2013, 09:52:38
Could you give me a hint how to encapsulate such "SD Card on/off funtionality" into functions and make them usable in CHDK?
If your intention is to prevent the Canon firmware from accessing the storage, then this isn't going to work. You'll get "memory card error", nothing else.

It's true that the current "remote shoot" protocol blocks the shooting process while image data is being transferred over USB. I think the protocol would need substantial rewrite* to allow working with JPEG images "cached" in RAM (filewrite would send information about JPEG chunks via messages to a separate "USB writer" task), and I'm not sure if that even could work reliably. Doing this with raw is out of question by the way...

No idea about the other wired or wireless external solutions.

edit:
* This sentence probably doesn't reflect correctly what I meant: I'm not suggesting that rewriting the protocol is important/urgent/...
« Last Edit: 20 / December / 2013, 11:38:44 by srsa_4c »
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Offline Karmaschinken

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Re: Shooting while transferring over USB
« Reply #12 on: 20 / December / 2013, 11:11:20 »
But is Canon all the time examining if the Card is present? If a JPG has been written to the Card after shooting and then the card would have somehow been disconnected while downloading the images, then be reconnnected, do you think Canons OS would recognize such a shortly "offlined" card?

I am not trying to prevent the image to be written to the card!
« Last Edit: 20 / December / 2013, 11:12:52 by Karmaschinken »
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Offline srsa_4c

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Re: Shooting while transferring over USB
« Reply #13 on: 20 / December / 2013, 11:32:40 »
Quote from: Karmaschinken on 20 / December / 2013, 11:11:20
But is Canon all the time examining if the Card is present?
The firmware checks every part of the process, any unexpected behaviour will be treated as an error condition.
Quote
If a JPG has been written to the Card after shooting and then the card would have somehow been disconnected while downloading the images, then be reconnnected, do you think Canons OS would recognize such a shortly "offlined" card?
The card is meant to reside in a closed compartment, and is expected to function normally. So, yes.
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Offline waterwingz

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Re: Shooting while transferring over USB
« Reply #14 on: 20 / December / 2013, 11:56:17 »
Quote from: srsa_4c on 20 / December / 2013, 11:32:40
Quote from: Karmaschinken on 20 / December / 2013, 11:11:20
But is Canon all the time examining if the Card is present?
The firmware checks every part of the process, any unexpected behaviour will be treated as an error condition.
I think I understand that part.  But once shooting is complete and the camera is essentially sitting idle, Karmaschinken is asking if it would notice that a short "power down" via a  CHDK task direct write to the appropriate digital I/O bit occurred,  followed shortly after that by a direct write causing a "power up".
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Offline Karmaschinken

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Re: Shooting while transferring over USB
« Reply #15 on: 20 / December / 2013, 12:10:01 »
Right! Although it's just a guess I cannot imagine that the camera while being completely idle would detect an error. Well, this is what I can try without problems.

How, btw., is the removal of a card detected? Is it a switch maybe similar to the one that detects the state of the battery compartment door?
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Offline Karmaschinken

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Re: Shooting while transferring over USB
« Reply #16 on: 20 / December / 2013, 12:13:15 »
Well, I could answer that myself: I tried with a micro-sd to sd adapter. I started the camera with the micro sd card in it, then, while the camera being on, removed the micro-sd-card. No error, everything ok. After putting the card back into the adapter I could shoot!

So this already might be the proof that the use of such adapter-extension-cable-thing is useful. Even not being able to disconnect the camera and the sd-card within CHDK code, it will be possible to have a switch that disconnects the cable physically from the camera, making it possible to download directly. This is very promising! I will try that asap, this might speed up the ups/downs from/to multiple cameras very much.
« Last Edit: 20 / December / 2013, 12:18:29 by Karmaschinken »
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Offline waterwingz

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Re: Shooting while transferring over USB
« Reply #17 on: 20 / December / 2013, 12:15:26 »
Quote from: Karmaschinken on 20 / December / 2013, 12:13:15
Well, I could answer that myself: I tried with a micro-sd to sd adapter. I started the camera with the micro sd card in it, then, while the camera being on, removed the micro-sd-card. No error, everything ok. After putting the card back into the adapter I could shoot!
Clever !   8)
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Ported :   A1200    SD940   G10    Powershot N    G16
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Offline reyalp

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Re: Shooting while transferring over USB
« Reply #18 on: 20 / December / 2013, 21:25:53 »
Quote from: Karmaschinken on 20 / December / 2013, 08:30:51
My idea is that maybe one could download from multiple cameras at the same time, because the cards could be mapped as drives. This would be in contrast to use PTP, which - as far as I understood - only allows to download from the cameras one after one. Is that right?
This is only true if you are using a single instance of chdkptp or ptpcam to do the download. If you run multiple instances, or write a client that is multithreaded or able to use async IO, you would be able to download from multiple cameras at the same time. Depending on the speed of the computer and camera USB interfaces, this may or may not be faster than downloading sequentially.

edit:
This thread http://chdk.setepontos.com/index.php?topic=5563.0 has some discussion of the "sd power" mmio mentioned by waterwingz
The last testing I did with that was somewhat inconclusive, but there are eventprocs so it's easy to play with.
« Last Edit: 20 / December / 2013, 22:14:25 by reyalp »
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Offline waterwingz

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Re: Shooting while transferring over USB
« Reply #19 on: 20 / December / 2013, 23:30:30 »
Quote from: reyalp on 20 / December / 2013, 21:25:53
This thread http://chdk.setepontos.com/index.php?topic=5563.0 has some discussion of the "sd power" mmio mentioned by waterwingz
The last testing I did with that was somewhat inconclusive, but there are eventprocs so it's easy to play with.
Any chance of a C&P error during the early part of that port so that the mmio values were not correct?
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Ported :   A1200    SD940   G10    Powershot N    G16
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