May 13, 2016 at 18:11How to stop worrying and start shooting correctly on a phantom
- Tutorial
You took the most beautiful and smooth spans from the copter, and after installation everything twitches? If the original video is delightful, and the result is tears, then perhaps the problem is in the wrong shooting mode.
If you open the list of all available, it is difficult to determine which mode to use - there are a lot of them: 24, 25, 30, 48, 50, 60 frames per second.
However, here everything is not so simple. If you look at the properties of the captured files, then instead of 24, 30, 48, and 60 we will see 23.976, 29.97, 47.952, and 59.94 there. And, although the difference is already in hundredths, with incorrect installation settings, we get jerks. Verified by personal experience.
It is worth noting that when editing aerial photography, an audio track is not used and therefore it is very easy to fix this in most editors. But this is the topic of a separate article.
Why all these 23.976, 24, 25, 29.97 and why you can not choose others? Where did such strange fractional numbers come from?
How often does this happen, the reason for all this ugliness is historical and these frequencies correspond to different standards:
Therefore, if the material that you shoot is used in reporting on TV, then you should use 25 or 50 frames per second.
In addition to the resolution, the image quality is also affected by bitrate, i.e., the amount of information for storing one second of video. In this case, the fantasy bitrate depends on the resolution, but the actual resolution may be limited by the quality of the optics, which is clearly demonstrated in the next video.
The Ambarella A9 video codec installed on the third phantom allows you to encode 4K video with a bitrate of 100Mbps. However, DJI limited this value to 60 Mbps for the PRO version. And, it’s unlikely that this is due to the speed of the memory cards - even inexpensive memory cards can write 12.5 MB / s, but we will choose what we have, that is.
Below is a summary table of the dependence of the DJI Phantom 3 Pro bitrate on frame rate and resolution (firmware version 1.6).
As you can see, in addition to 4K video with 60 Mbps is present when shooting at 1080 and 60 frames / s.
This raises the question: “Why should we shoot with a resolution higher than FullHD, if there is almost no equipment to view such content?” Answer: for video editing. Often during editing you have to crop the frame, or zoom in to fix the position of some object in it, and shooting in FullHD leaves no margin of resolution. But at the same time, the specific bitrate (bit per pixel) of a video with a higher resolution is lower. Hmm ... You feel the hand of the marketers. In fact, if you need a crop, you can shoot at 2.7K. If the frame rate is high, then 1080p 60fps. In support of the video about comparing video quality 1080, 2704, 4096 at 25 frames / s.
There is a myth that a person distinguishes only 24 frames per second. In fact, a person is able to discern a much faster frame change. The reason for choosing 24 frames per second, again historical, is a compromise between smoothness, film saving and sound quality on optical phonograms.
An example of an optical phonogram on film: As it’s not difficult to guess, the frame rate directly affects the smoothness of the video. Moreover, if on the ground shooting 24 frames are often preferred because of the “cinema picture” and focus on shooting people, then on panoramic frames, which are abundant in aerial shooting, there is clearly not enough smoothness.
You can understand how much the 24 frames are twitching at this link .
The rule helps to avoid troubles:
Thus, when we select the necessary frame rate, we need to answer many questions for ourselves. And get the answer you need, which, however, will not be universal.
It is also worth remembering that many errors can be fixed at post-production, and the worst thing is if you get an unknowing editor who will kill all the quality of the video. Unfortunately, this happened to us several times.
However, it is much worse if the source material trembles, to prevent this, read this article .
As for the choice of resolution and bitrate, the question remains open, but I note 3 modes:
Using DJI Phantom 3 Professional as an example, let's see the available shooting modes.
If you open the list of all available, it is difficult to determine which mode to use - there are a lot of them: 24, 25, 30, 48, 50, 60 frames per second.
However, here everything is not so simple. If you look at the properties of the captured files, then instead of 24, 30, 48, and 60 we will see 23.976, 29.97, 47.952, and 59.94 there. And, although the difference is already in hundredths, with incorrect installation settings, we get jerks. Verified by personal experience.
It is worth noting that when editing aerial photography, an audio track is not used and therefore it is very easy to fix this in most editors. But this is the topic of a separate article.
So which frame rate to choose? Standards
Why all these 23.976, 24, 25, 29.97 and why you can not choose others? Where did such strange fractional numbers come from?
How often does this happen, the reason for all this ugliness is historical and these frequencies correspond to different standards:
- 24/48 frames used in cinema
- 25/50 (PAL / SECAM) when broadcasting TV in Europe and Russia
- 23.976, 47.952 and 29.97, 59.94 (NTSC) when broadcasting TV in the USA and Japan - on television
Therefore, if the material that you shoot is used in reporting on TV, then you should use 25 or 50 frames per second.
So which frame rate to choose? Bit rate
In addition to the resolution, the image quality is also affected by bitrate, i.e., the amount of information for storing one second of video. In this case, the fantasy bitrate depends on the resolution, but the actual resolution may be limited by the quality of the optics, which is clearly demonstrated in the next video.
The Ambarella A9 video codec installed on the third phantom allows you to encode 4K video with a bitrate of 100Mbps. However, DJI limited this value to 60 Mbps for the PRO version. And, it’s unlikely that this is due to the speed of the memory cards - even inexpensive memory cards can write 12.5 MB / s, but we will choose what we have, that is.
Below is a summary table of the dependence of the DJI Phantom 3 Pro bitrate on frame rate and resolution (firmware version 1.6).
As you can see, in addition to 4K video with 60 Mbps is present when shooting at 1080 and 60 frames / s.
This raises the question: “Why should we shoot with a resolution higher than FullHD, if there is almost no equipment to view such content?” Answer: for video editing. Often during editing you have to crop the frame, or zoom in to fix the position of some object in it, and shooting in FullHD leaves no margin of resolution. But at the same time, the specific bitrate (bit per pixel) of a video with a higher resolution is lower. Hmm ... You feel the hand of the marketers. In fact, if you need a crop, you can shoot at 2.7K. If the frame rate is high, then 1080p 60fps. In support of the video about comparing video quality 1080, 2704, 4096 at 25 frames / s.
So which frame rate to choose? Smoothness
There is a myth that a person distinguishes only 24 frames per second. In fact, a person is able to discern a much faster frame change. The reason for choosing 24 frames per second, again historical, is a compromise between smoothness, film saving and sound quality on optical phonograms.
An example of an optical phonogram on film: As it’s not difficult to guess, the frame rate directly affects the smoothness of the video. Moreover, if on the ground shooting 24 frames are often preferred because of the “cinema picture” and focus on shooting people, then on panoramic frames, which are abundant in aerial shooting, there is clearly not enough smoothness.
You can understand how much the 24 frames are twitching at this link .
So which frame rate to choose? Equipment Alignment
The rule helps to avoid troubles:
- if the video uses video not only from the copter, then it’s a good rule to shoot with the same (or multiple) frame rate on all equipment.
Something like conclusions
Thus, when we select the necessary frame rate, we need to answer many questions for ourselves. And get the answer you need, which, however, will not be universal.
It is also worth remembering that many errors can be fixed at post-production, and the worst thing is if you get an unknowing editor who will kill all the quality of the video. Unfortunately, this happened to us several times.
However, it is much worse if the source material trembles, to prevent this, read this article .
As for the choice of resolution and bitrate, the question remains open, but I note 3 modes:
- 2.7K 24 fps if cropping is required
- 1080 30 frames / s, as having the highest specific bitrate
- 1080 60 frames / s, has the highest bit rate and frame rate.