04-04-2018 08:17 PM - edited 04-04-2018 08:21 PM
Can someone explain why 24fps causes larger files on the same settings than 30fps?
I get over an hour extra time at 30fps compared to 24 on my 32GB card.
Time comparison on a 32GB microSD:
1080p 30 M = 3h:22
1080p 24 M = 2h:14
04-05-2018 03:02 AM
Thanks. Apparently fps does indeed have a big effect on file size in this case. Files are over 40% larger on 24 vs 30fps, which doesn't make sense to me. Individual frames are the same resolution, and there are fewer of them. So how are the files "picking up more data on 24fps somehow"?
Someone please explain.
04-05-2018 05:51 AM
Is it possible you filmed with 30fps with Protune turned off and the 24fps with Protune turned on? If so, that would make sense as Protune records at a higher bitrate (more data).
04-05-2018 01:16 PM
Thanks. I verified that all settings are the same (including Protune "off").
I'd consider it negligible if it didn't mean 1 hour and 8 minutes less recording time on my card.
The recorded files, equal in length and in recorded content differ drastically in file-size accordingly.
I can't imagine anything wrong with the camera itself, I've always treated it gingerly.
Can anyone else do a simple test comparing available recording time in both 24 & 30fps and report back here?
04-05-2018 07:49 PM - edited 04-05-2018 07:52 PM
I think I got a bit closer to understanding what's going on:
On 24, 48, and 60 fps, file sizes and rec. time are pretty much identical (they all yield 2h:14). Only at 30 do I get the extra 1h:08.
This leads me to think that both 24 & 48 are in fact captured as 60fps and then interpolated down.
This would mean that you have 2.5 identical frames in 24fps that still reside in the file, but are skipped over in playback. A pretty colossal waste of space. I'm surprised the software doesn't "clean" that up. (Let me know if you know or can think of a better explanation).
Incidentally, all frame rates at both 720p and 1440p also give me 2h:14, which makes me rethink adjusting settings for economical file sizes altogether. 1080p 30 gives me the most time/ smallest file sizes at 3h:22, and is the only setting to do so.
Any further illumination on the (software) engineering responsible for this is appreciated :)
04-05-2018 09:21 PM - edited 04-05-2018 09:22 PM
It's an interesting theory, but how is it that the shutter can be slowed to 1/24 at 24fps if the camera is actually recording at 60fps?
That's the thing, it should slow the shutter, but it doesn't!
It captures at 60fps. I'm assuming shutter-speed is limited to 60, or a multiple of 30 (since 120fps is available at 720p). 24 can't be converted from 30 as smoothly as from 60, which is why 60 is what's used on everything but 30fps. And that's why 30fps yields the most efficient file size. It's my theory, but it's better than any other explanation I could find anywhere.
Someone with inside knowledge has got to be able to verify that...