FB: GeoDrone4K
lvl.4
Flight distance : 2676129 ft
Romania
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Sandisk Extreme Plus have an actual sustained speed in writing at 30 Mb/s. Practically is no difference in Pro, PLus and Extreme, all of them having the same sustained speed of 30Mb/s.
The sellers make a lot of noise related to something fake: The Burst speed rate...this is presented at 90 Mb/s, 100 Mb/s and so on...this is just for advertising, as your MPEG video will be written with sustained speed and not burst, as burst can be achieved only for very short amounts of time.
Actually if you look at V indicator, you will see the minimum write speed of card, as V30 = minimum 30Mb/s, V90= minimum 90Mb/s.
In this category, best micro sd card tested by us was Kingston Micro SD Canvas React Plus V90, with a very impressive performance, being the only one that keeps up with 6K videos (Extreme Pro from Sandisk flagged us that is too slow for a number of times).
Related to your problem, as A2S writing speed is up to 150MBPS = 150/8 = 18.75 Mb/s minimum writing sustained speed, all V30 cards should work ok...the problem is how the A2S is buffering the video then start empty the buffer and write on microsd...In fact, a few times I have seen that V30 is just not enough, as microsd producers does not deliver a very good quality in their Micro-SD memory cards so I would recommend you a V90 just to be on the safe side.
Each camera have a FOV and the size of sensor gives you the size of information that will be processed and saved. As the sensor have a speed of "reading" and "writing" the information given by FPS, if you make very fast moves, the sensor will not have time to "see" the image and save it...Think at this as an example: cover one eye with your hand, start blinking with the other eye at a constant speed (FPS), and start spinning slowly...you will see an image that can be followed in a pretty cursive mode...Now, with same blinking speed, start spinning fast...you will see disrupted/jitter images...
This is how the sensor and FPS works too...you need to maintain a max speed in order not to "frame"....For example, a simple calculation of how much time you need to turn your drone 180 degrees without seeing disrupted and jitter image is around 23 seconds at 30 FPS...yeah...right...If you put it at 60 FPS (remember your eye? is like blinking twice as fast), but you will get....around 19 seconds for a 180 degree turn...as you can see, doubling FPS does not give you half the time (double of speed) for turning the drone at 180 degrees.
Fur butter like video, you need to keep a very soft movement...
This is a simple explanation to help you understand the basics of video image. |
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