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Hidden 720p preview file on SD card

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I use a program called Photo Mechanic to ingest and rename media to my Mac from the various DSLR and video cameras I use. The ingest process is set to scan the memory card folders recursively and import whatever media files it finds in them.

When I started ingesting media from the I2 SD cards, I noticed I was getting an extra file for each video clip the I2 had recorded. When I checked, the extra files weren't visible when browsing the the SD card directories in the Mac's Finder, just the "proper" recording at whatever size I'd set it at. However, when i checked the extra files, I found they were playable video files and where at 720p.

All I can presume is that the I2 must be recording the 720p downlink video to a hidden directory on the SD card, and that Photo Mechanic is finding the file on ingest and importing it with the rest! If you're looking for a small & quick preview file to send/give to someone, then it's ideal - you'll just need to extract it from the card!

It works great for me for previewing as I'm still running on a 2006 MacPro for the moment and some of the 4K files need transcoding to be properly reviewable... which takes time!! (I'm waiting on Apple getting their finger out of the proverbial and releasing some updated Pro's or iMacs soon!)

I've also been using a P4 for a while and the hidde "preview" recording has never appeared on the ingests from that. I think I'll have a play around with the I2's 720p/1080p downlink settings to see if that changes the hidden preview recording resolution - would be a quick and easy way to score a 1080p recording alongside a 4K one!

Hope that hidden feature helps someone else out! (Not sure if the I1 did that too).
 
Last edited:
Just checked the results from this afternoons tests. I ran some with the downlink set to 720, and a few with it set to 1080. The hidden file is recorded in whatever you have the downlink res set to, so you can pluck out some quick 720 or 1080 copies free without a round trip thru your NLE :cool::cool::):)
 
Ok, so after a bit more digging around...

There's a hidden (on the Mac at least!) folder on the SD card called MISC. Inside that folder is one called THM. That in turn contains a numbered folder mirroring the main ones in the DCIM directory that contain your jpg, mov/mp4 and dng's. Inside the numbered folder are 'thumbnails' of the movies you've recorded on the card - these are the 'preview' ones in 720 or 1080 that match that of the downlink.

If, like me, you don't always reformat the sd card each, but simply delete the files instead, you'll find that the space on you SD card gradually gets less and less after each 'delete'. That's because you're only deleting the files in the DCIM directory and these smaller 'previews' are left behind. If you delete them, then you'll get your space back again. Also usefull if you've accidentally deleted a hi-res movie and want to recover something... you can at least get back a 720 res file if you haven't cleaned the MISC folder out too


SDCard
|
+ DCIM -----100MEDIA--- jpg, dng's, mov/mp4 (@ selected resolution)
| ... .. \__ 101MEDIA---jpg, dng's, mov/mp4 (@ selected resolution)
|
\_MISC ----- THM ----- 100 --- mov/mp4 (720 or 1080)
(hidden) \__ 101 --- mov/mp4 (720 or 1080)
 
I just noticed the same thing on a P4p, it must be imbedded in the go 4 app.
 
Interesting to hear it saves for the P4p - I'd wondered if it was a side-effect of the new multi-output video core in the I2, but if it's storing them for the P4p too, then it can't be. Doesn't do it with my P4 with the DJI Go 4 - checked earlier & it only stores stills thumbnails, no video.
 
the misc video on the p4p was 1080, I was shooting in 2.7 k and 48fps, haven't tried my p4 yet to see if it works there.
 

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