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P3A - Smudgy video

Discussion in 'Pro/Adv Discussion' started by RuneW, May 19, 2015.

  1. RuneW

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    I've now flown 3-4 times with my P3A and it behaves absolutely fantastic!

    There is some issues though. One of them is that the video (or rather parts of the video) becomes very, very "smudgy" at times. A prime example of this is at the center of the video below at ca 1:30:


    (please ignore the bad piloting for now)

    In addition there are some clear "shifts" going on. Both the smudginess and those shifts are, as far as I know, signs of very aggressive compression.

    Unfortunately this is something that we cannot change with the current firmware? I really hope this is something that can be change in future firmware versions, because this is not looking very good.

    The video (.mov) is moved straight from the SD card to youtube with no editing in between.
     
  2. dhaslam

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    What were outside temperatures like at the time? Did you move from a warm car to colder outside conditions? It could be a small trace of condensation on one of the lens elements.
     
  3. RuneW

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    The temperature was about 10 °C. Inside, maybe 22 °C.

    I cannot imagine condensation being a problem at these temperatures?

    And besides, condensation would gradually go away in the new temperature, but the same are of the lense is sharp half a minute before the smudginess part. At 0:55 it seems sharp enough.
     
  4. loganboyd

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    Does the original file have this same issue when played on your computer? YouTube will compress the file even further and reduce the bitrate.
     
  5. 4wd

    4wd

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    I think there is a softer spot in the centre with them all, it will be more apparent in some subjects and lighting conditions.
    What do you mean by 'shifts' - the exposure changing automatically?
    Manual setting would lock it but it's very easy to get this wrong as lighting changes - you can easily mess up much worse than the camera's automatic compensating.
     
  6. RuneW

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    Sorry. Bad wording. No, what I mean is visible shifts between P-frames, B-frames and I-frames in the compression. The video stream consists of I-frames (key frames) that is actually encoded and all these predicted (P-frames (forward predicted) and B-frames (bidirectionally predicted)) frames in between.

    http://en.wikipedia.org/wiki/Video_compression_picture_types

    If the compression is too agressive (and/or the distance between the I-frames is too large) the predicted images doesn't quite match the new I-frame and you can notice a "shift" in the image. Typically it looks like a "rhythmical clarification" (that's the I-frames) and then progressively degrading clarity until the next I-frame. It could also be the shift between the last P-frame and the first B-frame I see. The point is that the video quality is not constant.

    I see at least one other guy speculating about the foo few I-frames:



    Note: I'm no expert in in video compression...
     
    #6 RuneW, May 19, 2015
    Last edited: May 19, 2015
  7. RuneW

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    I will check this when I get home from work. It could certainly be youtube that is messing things up. But I have seen so many other beautiful videos on youtube that doesn't show these issues so clearly...
     
  8. bbfpv

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    I agree, it's gotta be youtube. The compression algo in the bird isn't a mechanical part that can fail, so we'd all be seeing those shifts if it was a problem.
     
  9. dhaslam

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    It seems that the green pixels are more affected than other colours but what seems to be happening is that certain objects, particularly trees start by being a bit blurry and stay like that when moving to a different part of the frame.
     
  10. ml92760

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    Hello everyone I'm new to the forum and I see others have an issue like mine.... I have a phantom three standard and I'm not getting any results from DJI with a video problem I am having ?
    .. here is a link to a video that shows the issue of pixelation in discoloration within the video I have no idea what's causing it not to correct it.. Unless this is corrected the thing is useless for any quality video... Another issue I'm having is for some reason some of the videos will not play as if they are not formatted correctly. ( also see others wit this issue as well) I have reformatted the SD card at least twice and still experience the same problem. Any help would be much appreciated ( or a link to a thread that will explain how to fix this) as DJI is not responding. short video link here.. note at 50 Sec Marker, 58 Sec marker and then it goes nuts 1:11 marker on and off and then hole parts at the end..??

    trying to get into some real estate photo work and this will not fly... pun intended : )



    Thanks !
     
  11. bobmyers

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    Did you remove the video from the SD card and put it on a good computer with a good video card to play it back?
     
  12. ml92760

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    Yes I did , I thought perhaps that was the issue as well, I also reformatted and attempted another card, and I have plenty of computer power.. Mac.... the thing is when I uploaded it to YouTube for display as you can see the same problem happened.. another issue is sometimes I cannot get the video to record on the ST card seems after reformat believe there's something going on with the camera although it's new.. may have to send it back to DJI ever get back to me... not the best support