Author Topic: Auto ETTR during recording  (Read 3329 times)

brapodam

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Auto ETTR during recording
« on: June 14, 2013, 01:26:31 PM »
Mainly useful for time lapse recording using raw video. Is this something that will be considered?

Before the suggestions on using RAW DNG silent pics instead pour in, I've found a few problems while using it:
-Interval between shots are slower than the interval set in intervalometer, at least for the intervals that I've tested. Makes it very unpredictable to use
-No recording while screen off (available in RAW video with memory hack)
-Offers no advantage in terms of deflickering compared to RAW video, since it doesn't write the XMP files
-Limit of 1000 shots (as reported by others, I've never exceeded 1000 shots in any time lapse)

I also have no idea how to do picoC scripting, but if anyone can point me in the right direction on how to make a script to trigger Auto ETTR at fixed intervals, that would be fine as well

Audionut

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Re: Auto ETTR during recording
« Reply #1 on: June 14, 2013, 04:52:20 PM »
Intervalometer+powersave+silent pic+AutoETTR (always on) in photo mode LV is working fine here on a 5D3.

Didn't test the 1000 shot theory, but you seem to imply that won't be a problem for you anyway.

Be handy to have the deflicker sidecar file saved with silent pic.  I kill my shutter enough as it is without playing with timelapses.

a1ex

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Re: Auto ETTR during recording
« Reply #2 on: June 14, 2013, 05:07:10 PM »
For recording, the algorithm would be quite a bit different IMO:

- don't try large steps (photo ETTR does that to converge quickly)
- smooth transitions (can be done with shutter speed or digital ISO, or maybe just by enabling gradual exposure)
- override settings with the HDR video method (per-frame), not via properties (where timing can't be controlled)
- deflicker in post (with the same algorithm used for post deflicker, but applied in the converter)

It's totally possible, but not very straightforward.

brapodam

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Re: Auto ETTR during recording
« Reply #3 on: June 14, 2013, 05:38:09 PM »
Intervalometer+powersave+silent pic+AutoETTR (always on) in photo mode LV is working fine here on a 5D3.

Didn't test the 1000 shot theory, but you seem to imply that won't be a problem for you anyway.

Be handy to have the deflicker sidecar file saved with silent pic.  I kill my shutter enough as it is without playing with timelapses.
Last time I checked, the moment powersave activated, capture of silent pics stop. Also, as I have mentioned before, the intervals do not work properly for me (I tested in M mode, so it should be the same as what you tested (photo mode LV))

I think with dhilung's frame skipping mod (http://www.magiclantern.fm/forum/index.php?topic=6451.0), and auto ettr during recording, RAW video for time lapse will become very viable (it's already pretty good now for scenes where exposure doesn't change much). I think this is all about using less shutter actuations. Intervalometer with normal RAW files are still better, but I think soon enough, RAW video will close the gap.

Audionut

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Re: Auto ETTR during recording
« Reply #4 on: June 14, 2013, 05:46:26 PM »
Last time I checked,

How many revisions ago?  As I mentioned, it was all working fine here.

brapodam

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Re: Auto ETTR during recording
« Reply #5 on: June 15, 2013, 08:03:59 AM »
How many revisions ago?  As I mentioned, it was all working fine here.
I don't know exactly how many revisions back. I just did a quick test today with the build from June 13 and here are the results:

-With an interval of 1s set in the intervalometer, the silent pics do not keep up.
-With an interval of 5s set in the intervalometer, the intervals seem normal
-Activating powersave manually will put the camera into powersave provided it is not currently capturing or saving a silent pic (I've set it to shut off LCD and globaldraw off), but camera wakes at the next silent pic
-Waiting for powersave to come on automatically does not work (camera does not enter powersave automatically - I've set it to activate at 30s). Maybe the powersave activation time has to be lower than the intervals between the silent pics

Audionut

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Re: Auto ETTR during recording
« Reply #6 on: June 15, 2013, 08:29:22 AM »
Silent pic does take a bit to process.  So yes, very small intervals will not keep up.

Forget about Canon powersave stuff.  ML powersave will be the best you can get.  The screen needs to be activated for the time silent pics does it's process.  So you can shut the LCD off, but it needs to activate again for silent pics.

You can't put the camera into full powersave (sleep) mode.  It obviously needs to be awake to do stuff!

AutoETTR needs the LV active to work.  So even if AutoETTR gets enabled with raw video, the LCD must remain active.

The only current advantages I see for using raw video for an intervalometer is that you can have very short intervals, and the LCD can remain fully deactivated.  The cons are increased processing time and currently a lack of deflicker options.

IMO, raw video and intervalometer are 2 different tasks.  Raw video shouldn't be hacked to provide the features of an intervalometer.  If the intervalomter is lacking, it should be improved.

brapodam

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Re: Auto ETTR during recording
« Reply #7 on: June 15, 2013, 08:47:06 AM »
Silent pic does take a bit to process.  So yes, very small intervals will not keep up.

Forget about Canon powersave stuff.  ML powersave will be the best you can get.  The screen needs to be activated for the time silent pics does it's process.  So you can shut the LCD off, but it needs to activate again for silent pics.

You can't put the camera into full powersave (sleep) mode.  It obviously needs to be awake to do stuff!

AutoETTR needs the LV active to work.  So even if AutoETTR gets enabled with raw video, the LCD must remain active.

The only current advantages I see for using raw video for an intervalometer is that you can have very short intervals, and the LCD can remain fully deactivated.  The cons are increased processing time and currently a lack of deflicker options.

IMO, raw video and intervalometer are 2 different tasks.  Raw video shouldn't be hacked to provide the features of an intervalometer.  If the intervalomter is lacking, it should be improved.

Intervalometer is not lacking, silent pics is. With the current implementation of silent pics, it doesn't offer any advantage over RAW video. It is, in fact, an inferior RAW video.

As for LCD screen on for Auto ETTR to work, if it has to be done, then I'll do it. Because that is still not a disadvantage over silent pics, since silent pics require LCD to be on anyway (unless your intervals are long enough).

Either way, would memory hack not be enough for Auto ETTR to work? I don't quite understand how it all works, but I always assumed that RAW video is something like an extension of silent pics, where the camera captures the footage from the live view buffer. If memory hack can enable the LCD to be off (I'm assuming here that live view is technically still active, just that it is not displayed to the LCD) while recording, then it should also be able to make Auto ETTR work with the screen off.