H.264 video at LOW framerate for time-lapse video - Feature Requests - CHDK Forum
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H.264 video at LOW framerate for time-lapse video

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Offline Jean Goulet

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H.264 video at LOW framerate for time-lapse video
« on: 11 / July / 2012, 15:18:42 »
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What are the chances CHDK can REDUCE the normal 24 fps video framerate of the SX1 IS or ELPH 310HS?

To something like 1 second per frame, or 10 seconds per frame?

The ELPH 310HS features high speed (240 fps) recording, but from the looks of it "low-speed video",  otherwise known as time-lapse video, is not built-in to the Canons.
They record at >30 Mbps using H.264.

Does H.264 support arbitrary framerates? Apparently yes...
Is the DIGIC processor hard-coded to record at 24 (or 240) fps? No idea...

This would be a great feature, can it be done with CHDK?

P.S. In the meantime I am using intervalometer but that is limited to around 2400 photos (8 GB card). It would be so much better to have a single .MOV file with all the frames in there, and move the position (frame) slider to quickly locate scenes of interest. And take advantage of video compression.

I am filming a fairly static scene and want to capture an event.

Space wise, it means 1920x1080 * 24fps at 40 Mbps works out to 320 Kbytes/frame.
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Offline Microfunguy

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Re: H.264 video at LOW framerate for time-lapse video
« Reply #1 on: 11 / July / 2012, 15:52:26 »
Quote from: Jean Goulet on 11 / July / 2012, 15:18:42
I am filming a fairly static scene and want to capture an event

A little strange to be shooting a movie of an essentially static scene.

Why not just use motion detection or an external sensor to trigger image capture ?


David
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Offline Jean Goulet

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Re: H.264 video at LOW framerate for time-lapse video
« Reply #2 on: 19 / July / 2012, 14:37:57 »
Because the scene is NOT static, in fact it moves nonstop. And I have to detect an event within that motion.

That's why I have to record continuously. In the hopes that CHDK can help.
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Offline philmoz

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Re: H.264 video at LOW framerate for time-lapse video
« Reply #3 on: 19 / July / 2012, 16:08:37 »
If you're going to create a timelapse video you don't need to shoot at the full camera resolution.
If you drop the resolution and use normal compression mode instead of fine you will get a lot more images on the memory card. Depending on the camera you may also be able to use much larger memory cards.

At the moment there is no way to adjust the frame rate of movie capture.
Even if you could you there is a 4GB file size limit for movies on all Canon cameras and there is also recording time limit imposed on most cameras (as little as 10 - 20 minutes for HD video).

You probably won't be able a shoot a timelapse at 1 frame per second on most cameras - 2-3 seconds per frame is about the best you will get.

Phil.
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Offline reyalp

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Re: H.264 video at LOW framerate for time-lapse video
« Reply #4 on: 19 / July / 2012, 16:22:35 »
Quote from: philmoz on 19 / July / 2012, 16:08:37
You probably won't be able a shoot a timelapse at 1 frame per second on most cameras - 2-3 seconds per frame is about the best you will get.
In the half res quick/low light modes ~1fps should be possible on many recent cams. Quality is lower than the equivalent res in normal modes though, and if the camera only has this in high ISO mode, you'll have to override the ISO back to a low value and probably do your own exposure calculations.
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Offline a1ex

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Re: H.264 video at LOW framerate for time-lapse video
« Reply #5 on: 19 / July / 2012, 16:33:10 »
You may try a Lua script that does this:
Code: [Select]
poke(0xC0F06008, 1234); // value of timer 1 - bigger value = lower FPS
poke(0xC0F06014, 1234); // value of timer 2
poke(0xC0F06000, 1); // apply settings

This code works on all Canon video dSLRs, but it might work on compacts too.

These values may not be safe - if so, use larger numbers or change only one timer. The resulting FPS is TG / timer1 / timer2, where TG is a camera-specific constant (typical values: 20 - 50 MHz).

I remember srsa_4c had some success with this.
« Last Edit: 19 / July / 2012, 16:51:35 by a1ex »
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Offline srsa_4c

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Re: H.264 video at LOW framerate for time-lapse video
« Reply #6 on: 19 / July / 2012, 16:43:12 »
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