Continuous Shooting vs. Group Playback

TurboLed

5

Continuous Shooting vs. Group Playback

« on: 05 / January / 2021, 12:11:14 »

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Hi
I own an SX270HS and something that annoys me is this: The pictures taken in Continuous Drive (with P mode for example) are not grouped in playback, whereas the pictures taken in Sports/HQ speed burst are grouped. This would be especially useful when doing bracketing with CHDK, when you don't want to review each shot individually.

I tried to compare the EXIF of pictures (with ExifTool) taken in Sports/HQ speed burst and P mode with Continuous Drive mode, tried to copy the ShootingMode, EasyMode, ContinuousDrive, FocusMode tags... But I still haven't found how the Canon camera decides to group pictures in playback or not.

I know some developer here have more knowledge on the firmware of those cameras, how the JPEG files are being saved, etc. Anybody has a clue on how the grouping is done?

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TurboLed

5

Re: Continuous Shooting vs. Group Playback

« Reply #1 on: 05 / January / 2021, 12:32:29 »

By the way, I 've just copied all the EXIF tags by using ExifTools -tagsFromFile and magically, my pictures in P-mode became grouped. So there's definitely something hidden in the EXIF somewhere that makes it work. I'm wondering if it comes from the ImageUniqueID tag...

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reyalp

14117

Re: Continuous Shooting vs. Group Playback

« Reply #2 on: 05 / January / 2021, 16:59:52 »

The only obvious candidate I see in diffing exiftool -h output for single shots and grouped from my SX730 is the "Shot Number In Continuous Burst". However extiftool -U gives a significant number of unknown tags, so something could easily be hiding in there.

Interestingly later models like SX730 do group continuous mode shots, so you're not the only one who thought it should be that way.

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c_joerg

1251

Re: Continuous Shooting vs. Group Playback

« Reply #3 on: 06 / January / 2021, 01:54:01 »

I have dealt with the problem before. Couldn't one also rename the images with CHDK that come from a series? Or would make the problem with the playback?

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TurboLed

5

Re: Continuous Shooting vs. Group Playback

« Reply #4 on: 06 / January / 2021, 10:35:57 »

Quote from: c_joerg on 06 / January / 2021, 01:54:01

I have dealt with the problem before. Couldn't one also rename the images with CHDK that come from a series? Or would make the problem with the playback?

The problem I see with that is that you would lose the ability to delete an entire series if the extra pictures in the series become hidden from the camera.

Quote from: reyalp on 05 / January / 2021, 16:59:52

However extiftool -U gives a significant number of unknown tags, so something could easily be hiding in there.

Thanks for the tip! I have found it! In the MakerNotes, there's an unknown tag named: "Canon_0x0032" that contains some binary data. This data is the same for every picture in one grouped series. By copying that tag among all my JPG files, they all become grouped together! To achieve this I had to create a custom config for ExifTool to be able to write to the tag.

Now my next step would be to manipulate the EXIF data after taking a series a picture. The TagMe lua script can be a good starting point.

EDIT: I'm still stuck, the Canon_0x0032 tag works to group several HQ burst together into one set, but it's not enough to group P-mode shots together. I'm getting close however.

« Last Edit: 06 / January / 2021, 12:54:56 by TurboLed »

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reyalp

14117

Re: Continuous Shooting vs. Group Playback

« Reply #5 on: 06 / January / 2021, 13:49:11 »

Quote from: TurboLed on 06 / January / 2021, 10:35:57

EDIT: I'm still stuck, the Canon_0x0032 tag works to group several HQ burst together into one set, but it's not enough to group P-mode shots together. I'm getting close however.

Maybe the firmware looks at the shooting mode or drive mode tags? Like "Canon Exposure Mode" or "Continuous Drive"?

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Don't forget what the H stands for.

TurboLed

5

Re: Continuous Shooting vs. Group Playback

« Reply #6 on: 06 / January / 2021, 14:47:21 »

Following up.

It's simpler than I thought. The second integer in the Canon_0x0032 tag needs to be changed from 1 to 2. Then the consecutive pictures in a continuous drive are grouped in playback. Nothing else needs to change, it works even for pictures in P-mode.

When copying the entire content of Canon_0x0032, I can merge multiple sequence together. I guess there is some sort of Unique ID in there. Even if they are a mix of P-mode and HQ burst mode, they get merged but they show their individual modes in playback.

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reyalp

14117

Re: Continuous Shooting vs. Group Playback

« Reply #7 on: 06 / January / 2021, 18:01:59 »

Quote from: TurboLed on 06 / January / 2021, 14:47:21

Following up.

It's simpler than I thought. The second integer in the Canon_0x0032 tag needs to be changed from 1 to 2. Then the consecutive pictures in a continuous drive are grouped in playback. Nothing else needs to change, it works even for pictures in P-mode.

Nice work. I don't know specifically, but I imagine the people who maintain exiftool appreciate getting information like like this.

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Don't forget what the H stands for.

TurboLed

5

Re: Continuous Shooting vs. Group Playback

« Reply #8 on: 11 / January / 2021, 10:14:41 »

Here's what I did to make it work. Nothing clean but it works for my needs.

1-Modified fwt_open and fwt_write to keep track of the write position and modify the byte at position 0x1230 from 1 to 2 (in my case this corresponds to the second byte of the Canon_0x0032 tag of the MakerNotes). The EXIF data should be parsed appropriately instead of doing this.

2-Added code in main.c to remove all files in the A/DCIM/CANONMSC folder, right after the spytask_can_start while loop. This forces the camera to re-generate the CTG files. As of this,the grouping doesn't take effect in playback until the camera is restarted.

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