4k60p is.. not true 4k.

Andrei V · Dec 2, 2016

I did a few picture quality tests this afternoon, including one to test the differences between 24/30/48/60fps in 4k mode (h.264). It seems that the sensor readout is skipping lines once you're shooting in 48/60p which results in rather noticable softness/aliasing of the overall image. 4k/48p and 4k/60p are really closer to 1080p in terms of vertical resolution than 4k

Screen grabs from 400% zooms attached

AIRSPACE · Dec 2, 2016

There is a noticeable difference between 60fps and 24fps. The 24fps is way better but the 60fps is still acceptable. Heres a video a shot in 60fps 4k today. The 100mbps bitrate is not enough for 4k 60fps imo. Its similar to the P4 really but with the added benefit of slow mo.

smiller · Dec 2, 2016

Yes, 4K 60 fps may be stretching bandwidth limits at H.264, please try again with H.265 to see if there is a difference.

hidaven · Dec 2, 2016

H.265 cant run in 4k 60fps.

hidaven · Dec 2, 2016

Only 30FPS, looks like H.264 at 60FPS is interlaced! lol. Add that to the reduced range and we see some marketing mumbo jumbo....Mines going back. lets hope they get their act together with the P5.

Andrei V · Dec 2, 2016

smiller said:
Yes, 4K 60 fps may be stretching bandwidth limits at H.264, please try again with H.265 to see if there is a difference.

I don't think it's a question of codec bandwidth.. most likely the readout speed of the sensor limits DJI to only reading every other horizontal line or so when in 48/60p. It's a bit disappointing, but still an improvement over the P4, at least. Ultimately, it means you're better off shooting at 24 or 30p unless you what you're filming would really benefit from slow motion.

Next up -- has anyone done any comprehensive testing of h.265 vs h.264 quality?

And how about the "mechanical shutter" business? Is the camera actually using a mechanical shutter to eliminate the jello effect? Should be easy to test with some fast pans..

smiller · Dec 2, 2016

hidaven said:
Mines going back.

Thank God.

gfagien · Dec 2, 2016

It's not that it's not true 4k but that you only have 100 megabits of data to play with.

If you film 4k 30 or 4k 60 you only have 100 so when you film in 4k 30 you have more information per frame, when you film in 4k 60 you have to stretch that 100 megabits to 60 frames from 30

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Andrei V · Dec 2, 2016

gfagien said:
It's not that it's not true 4k but that you only have 100 megabits of data to play with.

If you film 4k 30 or 4k 60 you only have 100 so when you film in 4k 30 you have more information per frame, when you film in 4k 60 you have to stretch that 100 megabits to 60 frames from 30

Sent from my iPhone using PhantomPilots

I understand the potential limitation of squeezing more frames into the same 100mbs, but the differences in the 4k/60p footage aren't compression artifacts -- it's general softness, aliasing, moire. Pretty sure they would be there even if you had twice or ten times the bandwidth because they're caused by the way the sensor is being sampled at higher frame rates.

Also, h.264 and h.265 are long GOP codecs -- which means that doubling the frame rate within the same bandwidth doesn't actually halve the information used to represent each frame, since most frames are are simply represented as the difference from prior frames. A higher framerate usually (but not always) means there's fewer differences between subsequent frames, so less data needs to be recorded per frame. So theoretically you should be seeing some basic degradation in detail because of the bandwidth limitations, but it shouldn't be massive.

gfagien · Dec 2, 2016

The issues you are mentioning are the same issues we GH4 users have, we have softer images using 60p over 30p and it is due to the nitrate not being enough data to give as sharp images

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smiller · Dec 2, 2016

4K at 60 fps is a whole lotta bits.

hidaven · Dec 2, 2016

Well then don't advertise 4k at 60fps if you cant walk the walk.......Combine this with a definite reduction in flight distance over the Mavic and you have marketing mumbo jumbo as Smiller states eloquently..........

smiller · Dec 2, 2016

hidaven said:
Well then don't advertise 4k at 60fps if you cant walk the walk.......Combine this with a definite reduction in flight distance over the Mavic and you have marketing mumbo jumbo as Smiller states eloquently..........

If you're quoting what smiller thinks, smiller thinks you're a troll.

hidaven · Dec 2, 2016

I taught Smiller everything he knows about flying. ......I have owned every quad DJI has put out in the last 10 years. This is the first major disappointment esp. considering the cost of 1800.00. I'll stick with my Mavic and P4. Demanding quality for my dollar? Yes, troll no.

Dronefriend · Dec 2, 2016

I don't care about 4Kp60. If I need slowmo I'll shoot that in 1080p120 @ h265, no contest. I will never shoot anything in h264 again.

As for the range, I'll believe it when I see it myself.

tml4191 · Dec 2, 2016

hidaven said:
Only 30FPS, looks like H.264 at 60FPS is interlaced! lol. Add that to the reduced range and we see some marketing mumbo jumbo....Mines going back. lets hope they get their act together with the P5.

If you aren't able to send it back, are you willing to sell it to me?

Roamer105 · Dec 2, 2016

All of it is 4K video. The problem is all in the encoder technology and recording bitrate. There is definitively not sensor scan speed problem since it allows a 1/8000s shutter speed. The amount of data to encode at 60fps is nearly 3 times as much as at 24fps. Since the encoding technology and bitrate is the same for all three settings in somewhat simplistic view: At 60fps (as compared to 24fps), the encoder must arbitrate away 2 out of 3 bits of information. The targets for this arbitration are pixels that have very little change in the YUV values - or in this case, they must have a 3 times more significant change in value. The result: loss of detail of course which makes the image "softer", kind-of "out-of-focus".

Roamer105 · Dec 2, 2016

Aside from the mechanical shutter and iris which eliminate a possible "jello" effect, the RECORDED P4P video (not image) quality would be no better than what you get from a P4 or P3P if the same encoder and bitrate are used. Sure, the optics are different, but in all fairness, the encoder limitations washes away most of the possible quality improvements. Again, I am talking strictly VIDEO - not still pictures. The P4P will produce a significantly better still picture than the P4 given the 20MP sensor.

The really important camera improvements for VIDEO are: 1) mechanical shutter and 2) 100mb/s H265 encoding for 4K/UHD at 24/30 fps.

Andrei V · Dec 2, 2016

Roamer105 said:
All of it is 4K video. The problem is all in the encoder technology and recording bitrate. There is definitively not sensor scan speed problem since it allows a 1/8000s shutter speed. The amount of data to encode at 60fps is nearly 3 times as much as at 24fps. Since the encoding technology and bitrate is the same for all three settings in somewhat simplistic view: At 60fps (as compared to 24fps), the encoder must arbitrate away 2 out of 3 bits of information. The targets for this arbitration are pixels that have very little change in the YUV values - or in this case, they must have a 3 times more significant change in value. The result: loss of detail of course which makes the image "softer", kind-of "out-of-focus".

Guys -- it's not softness. It's aliasing and moire. Take a look at the stems of the flowers in the screen grabs I posted or the roof in rustlecrowe's footage.

Andrei V · Dec 2, 2016

Roamer105 said:
Aside from the mechanical shutter and iris which eliminate a possible "jello" effect, the RECORDED P4P video (not image) quality would be no better than what you get from a P4 or P3P if the same encoder and bitrate are used. Sure, the optics are different, but in all fairness, the encoder limitations washes away most of the possible quality improvements. Again, I am talking strictly VIDEO - not still pictures. The P4P will produce a significantly better still picture than the P4 given the 20MP sensor.

The really important camera improvements for VIDEO are: 1) mechanical shutter and 2) 100mb/s H265 encoding for 4K/UHD at 24/30 fps.

Have you tested these camera improvement? Re: #2, I ran more tests this morning and I see zero difference in h265 vs h264 encoding quality at 24, 25 or 30p. See attached framegrabs. Granted, 100mb/s is still a noticeable improvement oven 60mb/s, so there is that, not to mention resolution, noise and dynamic range improvements owed to the larger sensor, which I don't think are completely negated, even at low bitrates. (compare p4/p3p/x3 video with x5 video sometime -- the differences are obvious even at 60mbs).

As to #1, until someone demonstrates otherwise, I'm working on the assumption that the mechanical shutter is only used for photos, not for video (as is the case with every other camera out there). DJI never advertised that the mechanical shutter is used to eliminate rolling shutter effects -- they just advertised that they incorporated a mechanical shutter into the physical camera module, where the p4/p3 had none.