S95 - Overcome maximum video duration - General Help and Assistance on using CHDK stable releases

Rarald

3

S95 - Overcome maximum video duration

« on: 02 / March / 2011, 07:14:49 »

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Hello there,

I would like to mount my S95 outside my plane and let it shot video during flight. I've done that before with a sport camera, but the rolling shutter of the CMOS sensor gave awful distortions in the image. I shall not have this problem with the S95 as it has a CCD sensor.

By default, the maximum video duration is around 27 min. The camera stops recording when the file reaches 4 Go exactly (maximum file size on FAT32 system). I successfully installed CHDK and reduces the video quality to 60, but in this case the camera stops when the files reaches exactly 30 min, although the file is around 2.4 Go. I guess this is nothing else than an intentional software limit.

Using CHDK, is it possible to get ride of this 30 min duration limit and have the camera recording until the file reaches 4 Go ? Alternatively, is it possible to have the camera automatically starting a new video when the recording stops? I cannot access the camera during flight and I would like it to record until I land or the battery is empty.

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Microfunguy

4037

Re: S95 - Overcome maximum video duration

« Reply #1 on: 02 / March / 2011, 07:33:24 »

Hello and welcome.

Well, with SDM the following single script command records for 30 minutes :-

shoot_movie_for 1800
sleep_for_seconds 5
shoot_movie_for 1800

etc or put in a loop to repeat.

If there is some reason why it is essential that you use CHDK, then presumably the same can be achieved though requiring a far longer script.

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zeno

891

Re: S95 - Overcome maximum video duration

« Reply #2 on: 02 / March / 2011, 07:35:43 »

With SDM (rather than CHDK) the script is pretty simple:

Code: [Select]

  rem do for as long as possible
  while 1
     rem shoot 29.5 mins of video (just to be safe)
     shoot_movie for (29*60 + 30)
     rem wait while card is written to (just to be safe)
     sleep_for_seconds 10 
  wend

You could try recording for 29' 59" seconds and reduce the subsequent sleep to just 1 or 2 seconds - I'm just playing safe here

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A570, S100, Ixus 127
Author of ASSIST, STICK, WASP, ACID, SDMInst, LICKS, WICKS, MacBoot, UBDB, CFGEdit

Rarald

3

Re: S95 - Overcome maximum video duration

« Reply #3 on: 02 / March / 2011, 14:40:46 »

Thanks guys. I understand that SDM is targeting stereo capture, which is not my goal. Does SDM has all functions of CHDK? Why would be preferable to use SDM rather than CHDK?

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Microfunguy

4037

Re: S95 - Overcome maximum video duration

« Reply #4 on: 02 / March / 2011, 16:11:00 »

Quote from: Rarald on 02 / March / 2011, 14:40:46

I understand that SDM is targeting stereo capture, which is not my goal.

If you go to the website you will find that is incorrect.
It says that it "aids 2D, stereo, multi-camera and kite-aerial photography (KAP) with certain Canon compact cameras" and "It has been to the edge of space in a balloon and to the cold of the Antarctic."

http://stereo.jpn.org/eng/sdm/index.htm

Quote

Does SDM has all functions of CHDK?

It does not have Lua scripting.
What functions do you require ?

Quote

Why would be preferable to use SDM rather than CHDK?

Read about the features of both, or better still try them and then decide which suits your particular purpose.
You can use both if you wish.
Load both DISKBOOT.BIN's onto a bootable card and temporarily rename the one you are not using.

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Rarald

3

Re: S95 - Overcome maximum video duration

« Reply #5 on: 06 / March / 2011, 07:46:08 »

I have been experimenting to get a better understanding on how these things work.

Say that I want to take a picture from the cockpit, i.e. behind the glass. It is typically not flat and has scratches or dirt. This gives two problems: dirt is visible on the image and the auto-focus tend to focus on the dirt rather than on the landscape.

The only way I found to get ride of this is to open at F/2 and manually set the focus to infinity. This makes the dirt as far as possible from the DoF and thus less visible. If there is a lot of sun, the minimum integration time of 1/1600 s is yet too long. Using chdk, I override it to say 1/10000 s. The integration time is actually override, but this is a fix setting, so the image rarely has the correct exposure. As the light condition changes a lot in the sky depending on what you are shotting at, it would more useful to shot in aperture priority mode and let the camera adjust the integration time, but with a lower limit down to 1/10000 s or so. Is it possible?

Related question is how the camera adjust the aperture in video mode? Is it possible to force the aperture to f/2, the focus to infinity and the shortest integration below 1/1600 s for the same reason as above?

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