Video Resolution with DJI Fly (Android) App?

[jclarkw]

Can somebody please clarify the available video resolutions with the Mavic Air 2 and DJI Fly app? In the app I can see various options, but I can't figure out which are the higher resolution ones. In the right-middle column (after Video has been selected in the right column in DJI Fly) the three choices are Normal, HDR, and Slow Motion. Neglecting the latter, in the left-middle column there are the following sub-selections: 4K Zoom (not available in Normal), 4K Wide, 2.7K, and 1080p. Then the left column has various fps selections (not all available for all options), although I've so far stuck with 30fps. (These options don't correspond exactly to those listed in the Mavic Air 2 specifications.)

I'm looking to get the maximum video resolution, particularly in case I want to grab frames from a video for decent stills, but all the combinations I've tried so far give the same data rate, 12,700 KB/s +/- less than 100. What am I missing here? -- jclarkw

 

[Pappy]

What you're missing is a MegaBit to KiloByte conversion.

Here's a video thumbnail of one of my video clips recorded in 4K HDR.



It shows the clip was recorded at 100.98 Mb/s. Notice the lowercase "b" in "Mb/s", this indicates the rate is in MegaBits per second. An uppercase "B" would indicate MegaBytes per second. So now the data rate needs to be converted to kB/s in order to compare. The conversion rate from Mb to kB is 1 Mb = 125 kB. Multiplying 100.98 Mb/s by 125kB/s gives you 12,625 kB/s, which is in the ball park of the number you have observed from your videos.

 

[jclarkw]

What you're missing is a MegaBit to KiloByte conversion...

Pappy -- Thanks for your response, but might we be talking past one another?

The 12,700 KB/s figure in my OP is the size of the .MP4 file on disk (in KB -- probably means kB) divided by the duration of the file in seconds (both reported by Windows 10 File Explorer). My point is that all the videos I've made (different durations and different video options as described above) give nearly the same ratio of file size divided by time. I was computing this ratio to try to determine which option gave the best video resolution, but they seem to all be the same! That's why I'm confused.

(I also don't understand what the various options, as reported by the DJI Fly app, actually mean.) -- jclarkw

 

[Repaid1]

(I also don't understand what the various options, as reported by the DJI Fly app, actually mean.) -- jclarkw

Just dial in one of the 4K options at 60fps...watch this video specifically at the 1:10 mark and look at his output.

 

[Pappy]

Pappy -- Thanks for your response, but might we be talking past one another?

The 12,700 KB/s figure in my OP is the size of the .MP4 file on disk (in KB -- probably means kB) divided by the duration of the file in seconds (both reported by Windows 10 File Explorer). My point is that all the videos I've made (different durations and different video options as described above) give nearly the same ratio of file size divided by time. I was computing this ratio to try to determine which option gave the best video resolution, but they seem to all be the same! That's why I'm confused.

(I also don't understand what the various options, as reported by the DJI Fly app, actually mean.) -- jclarkw

What you are computing is the recorded data rate which should be a fairly constant value, regardless of the video duration for the same resolution and frame rate. The MA2 specs state that the MaxBitRate is 120Mbps.

I would start with 4k @ 24 or 30 fps in d-cinelike would probably give you the best results. d-cinelike will have a flat color profile to allow more leeway on how much you want to adjust the captured frame. Or you can just find a static scene and record 10 second videos for each of the 4K variations to determine what is the best setting to use for frame captures.

 

[Dave Maine]

4K, 2.7k and 1080 all define different resolutions, with 4K being the highest, depending from there.

Bit rates are determined by the resolution selected, and the compression and amount of it being used. Lower bit rates mean more compression, and lower image quality.

 

[jclarkw]

...I would start with 4k @ 24 or 30 fps in d-cinelike would probably give you the best results. d-cinelike will have a flat color profile to allow more leeway on how much you want to adjust the captured frame. Or you can just find a static scene and record 10 second videos for each of the 4K variations to determine what is the best setting to use for frame captures.

Pappy -- Good thoughts. Two follow-ups if I may:

1) What is "d-cinelike," and how do I select it (given the apparent limitations of the DJI Fly app)?

2) What is the difference between "Normal" and "HDR," listed in the right-middle column (see OP)?

Thanks again -- jclarkw

 

[Dave Maine]

d-cinelike is a lower contrast adjustment designed for getting the maximum tonal range from high contrast situations.

HDR is a tonal range adjustment to support full HDR TVs.

 

[jclarkw]

d-cinelike is a lower contrast adjustment designed for getting the maximum tonal range from high contrast situations...

Dave -- I'm not seeing any such setting in the DJI Fly app. I see only "Normal," "HDR" (which I now understand) and (probably not relevant to the present discussion) "Slow Motion." What app are you (and Repaid1) using with the Mavic Air 2?

(I neglected to mention that I'm running DJI Fly vs. 1.2.1 under Android, which has some convenience value because I understand that CsvView cannot yet decode logs from vs. 1.2.2 and later.) -- jclarkw

 

[Dave Maine]

I was just responding to your questions. I fly a Phantom 4adv, Mavic Air 1, and Phantom 3 4k, all of which do have those settings. Don'tknow about others

 

[jclarkw]

I was just responding to your questions. I fly a Phantom 4adv, Mavic Air 1, and Phantom 3 4k, all of which do have those settings. Don'tknow about others

Fair enough. Thanks! -- jclarkw

 

[MavicAir2Marc]

D-Cinelike is in the 3 dot menu in the upper right hand corner. I think it would be under the camera tab (you might have to scroll down to see the setting)

 

[jclarkw]

D-Cinelike is in the 3 dot menu in the upper right hand corner. I think it would be under the camera tab (you might have to scroll down to see the setting)

So it is! Only shows up (under Camera/Color) when both the A/C is connected (powered on) and the camera is set to video.

The only other choice there is Normal. Since the same three choices remain in the 2nd-from-right column on the main screen (currently set to Normal?!), I don't know what effect it might have to change to that setting to HDR. Perhaps the menu setting you pointed out preempts? -- jclarkw