How to stop worrying and start shooting properly on the phantom
Have you removed beautiful and smooth spans from the copter, and after installation everything is twitching? If the original video causes delight, 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, 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 there 23.976, 29.97, 47.952 and 59.94. And, although the difference is already in hundredths, with incorrect installation settings, we will get jerking. Tested on personal experience.
')
It is worth noting that the audio track is not used during the installation of airborne surveys, and therefore it is very easy to fix in most editors. But this is a topic for 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?
As is often the case, the reason for all this disgrace is historical and these frequencies correspond to different standards:
Therefore, if the material you are shooting is used in a TV report, you should use 25 or 50 frames per second.
In addition to the resolution, the quality of the picture is also influenced by the bitrate (bitrate), i.e. the amount of information to store one second of video. In this case, the fan 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 bit rate of 100 Mbps. However, DJI has limited this value to 60 Mbit / s in the PRO version. And it is unlikely that this is due to the speed of the memory cards - even inexpensive memory cards can write 12.5 MB / s, but what we have, that is, we will choose from this.
Below is a summary table of the DJI Phantom 3 Pro bit rate versus frame rate and resolution (firmware version 1.6).
As you can see, in addition to 4K video with 60Mbps is present when shooting at 1080 and 60 frames / s.
Then the question arises: “Why do we need to shoot with a resolution greater than FullHD, if there is almost no equipment for viewing such content?”. Answer: for video editing. Often, the installation has to crop the frame, or zoom in to fix the position of an object in it, and shooting in FullHD leaves no resolution stock. But at the same time, the specific bit rate (bits per pixel) of a video with higher resolution is lower. Hmm ... feels the hand of marketers. In fact, if you need cropping, you can shoot at 2.7K. If the frame rate is high, then 1080p 60fps. In confirmation of the video about the comparison of the quality of video 1080, 2704, 4096 at 25 frames / sec.
There is a myth that a person distinguishes only 24 frames per second. In fact, a person is able to distinguish significantly faster frame rates. The reason for choosing 24 frames per second, again, is historical, it is a compromise between smoothness, film saving and sound quality on an optical sound track.
An example of an optical phonogram on film. As it is not difficult to guess the frame rate directly affects the smoothness of the video. Moreover, while on land shooting, 24 frames are often preferred because of the “cinema picture” and the focus on shooting people, then on panoramic shots that are too abundant in aerial shooting, smoothness is clearly not enough.
Understand how much 24 frames twitch can be on this link .
The rule helps to avoid problems:
Thus, when we select the necessary frame rate, we need to answer many questions for ourselves. And get the answer you need for yourself, which, however, will not be universal.
It is also worth remembering that many errors can be corrected in post-production, and the worst thing is if an unknowing installer is caught who will kill all video quality. Unfortunately, this has happened several times with us.
However, it is much worse if the source material is shaking, so as to prevent this, read this article .
By choice of resolution and bit rate, the question remains open, but I will note 3 modes:
Using the example of DJI Phantom 3 Professional, we will look at 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, 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 there 23.976, 29.97, 47.952 and 59.94. And, although the difference is already in hundredths, with incorrect installation settings, we will get jerking. Tested on personal experience.
')
It is worth noting that the audio track is not used during the installation of airborne surveys, and therefore it is very easy to fix in most editors. But this is a topic for a separate article.
So how do you choose the frame rate? 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?
As is often the case, the reason for all this disgrace is historical and these frequencies correspond to different standards:
- 24/48 frames used in cinema
- 25/50 (PAL / SECAM) for TV broadcasting 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 you are shooting is used in a TV report, you should use 25 or 50 frames per second.
So how do you choose the frame rate? Bitrate
In addition to the resolution, the quality of the picture is also influenced by the bitrate (bitrate), i.e. the amount of information to store one second of video. In this case, the fan 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 bit rate of 100 Mbps. However, DJI has limited this value to 60 Mbit / s in the PRO version. And it is unlikely that this is due to the speed of the memory cards - even inexpensive memory cards can write 12.5 MB / s, but what we have, that is, we will choose from this.
Below is a summary table of the DJI Phantom 3 Pro bit rate versus frame rate and resolution (firmware version 1.6).
As you can see, in addition to 4K video with 60Mbps is present when shooting at 1080 and 60 frames / s.
Then the question arises: “Why do we need to shoot with a resolution greater than FullHD, if there is almost no equipment for viewing such content?”. Answer: for video editing. Often, the installation has to crop the frame, or zoom in to fix the position of an object in it, and shooting in FullHD leaves no resolution stock. But at the same time, the specific bit rate (bits per pixel) of a video with higher resolution is lower. Hmm ... feels the hand of marketers. In fact, if you need cropping, you can shoot at 2.7K. If the frame rate is high, then 1080p 60fps. In confirmation of the video about the comparison of the quality of video 1080, 2704, 4096 at 25 frames / sec.
So how do you choose the frame rate? Smoothness
There is a myth that a person distinguishes only 24 frames per second. In fact, a person is able to distinguish significantly faster frame rates. The reason for choosing 24 frames per second, again, is historical, it is a compromise between smoothness, film saving and sound quality on an optical sound track.
An example of an optical phonogram on film. As it is not difficult to guess the frame rate directly affects the smoothness of the video. Moreover, while on land shooting, 24 frames are often preferred because of the “cinema picture” and the focus on shooting people, then on panoramic shots that are too abundant in aerial shooting, smoothness is clearly not enough.
Understand how much 24 frames twitch can be on this link .
So how do you choose the frame rate? Combination of equipment
The rule helps to avoid problems:
- if the video uses video not only from the copter, then a good rule would be to shoot with the same (or multiple) frame rate on all the 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 for yourself, which, however, will not be universal.
It is also worth remembering that many errors can be corrected in post-production, and the worst thing is if an unknowing installer is caught who will kill all video quality. Unfortunately, this has happened several times with us.
However, it is much worse if the source material is shaking, so as to prevent this, read this article .
By choice of resolution and bit rate, the question remains open, but I will note 3 modes:
- 2.7K 24 fps if framing is needed
- 1080 30 frames / s, as having the highest specific bitrate
- 1080 60 frames / s, has the highest bit rate and frame rate.
Source: https://habr.com/ru/post/394161/
All Articles