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P3 Professional 4K bit rate

Discussion in 'Pro/Adv Discussion' started by dondonner, May 24, 2015.

  1. dondonner

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    Had my P3P for a couple of days and some some flying.

    Noticed a number of times in my footage that the bit-rate of the video seems to drop out briefly and result in some really horrible and obvious compression artifacts in the footage.

    For example if you fly forward with the camera pointing down and then slowly pan up, watch as the camera struggles with the bit rate, you lose tons of detail until the pan stops and it recovers.

    So at the moment, very disappointed with the capability of this camera. It might do 4k resolution but the bit-rate is so bad that any kind of medium pace movement and the camera struggles in a really obvious way.

    Be interested to hear if anyone else noticed it, or maybe if there is something I'm doing wrong but the problem is visible in the source video before any kind of editing/cutting so I'm not sure there is much I can do there.
     
  2. blade strike

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    Doesn't sound like bit rate but shutter to high..
     
  3. dondonner

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    You mean my shutter speed was too fast? That would show an underexposed image, I'm not seeing that.

    I'm seeing very obvious compression artifacts, that is a bitrate issue and nothing else.
     
  4. loganboyd

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  5. windexh8er

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    I've noticed this in some publicly posted videos as well as my own. I really hope that the bottleneck is somewhere in the firmware and not the encoding hardware (which could be a byproduct of running too hot / insufficient cooling).

    I have a Samsung NX1 that does 4k in camera and the comparable footage is far smoother (which I would expect) however I'm not 100% impressed with the capabilities at this point after having a few flights in. When doing cinematic planning of the shots I find I'm thinking more about avoiding pan and tilt in an aggressively contrasted scene (think skyline / bridge vs relatively light background). When the scene is relatively static there are no issues, but complex shots have not been as expected. Wish we could get thermals off the camera processors in-app.
     
  6. dondonner

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    Yep exactly. And what happens when that bitrate limit is reached is really obvious with the P3P camera. Some cameras handle it better, this seems to drop out much worse than my GoPro black which also has a 60mbps bitrate.
     
  7. blade strike

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    Is it a strobing effect?
     
  8. dondonner

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    The best way I can describe it is the image seems to pixelate and you lose detail in the image.

    Here is a clip I put on youtube to show it. Youtube's own compression seems to cover the problem slightly but about 3 seconds in, the whole image fuzzes out, then comes back.

    this is visible much more in the source image at 4k.

     
  9. blade strike

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    It looks like strobing effect do to running a high shutter speed.. Private Ryan type effect..

    Try putting the camera in manual and also turn sharping down to -1

    Problem is we need nd filters really bad.
     
  10. dondonner

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    If you are talking about rolling image shutter problem then I don't think it's that. I know what that looks like and it's not this, This problem happens mostly during fast pan/tilt or with lots of motion. in this case I'm pointing down at grass which requires a lot of bitrate to capture all the fine detail.

    If you look at the still images from the source - the image pixelates. Shutter speed does not affect pixelation, the only thing that affects that is bitrate.
     
  11. blade strike

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    No, not rolling shutter.. When you run a high shutter speeds it can create strobing effect. It looks very similar to pixelation but more of a strobing or flashing in the pixels.

    Remember to have some motion blur and such you should be at around 60 for shutter if shooting at 30fps. There is no way you can get there unless you have a nd. I bet you were in auto and at a very high shutter (1600?)
     
  12. Johann

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    I also think its the bitrate, because blocking is only related to a hard working codec: Blocking.jpg lots of blocking going on in this 150% crop picture
     
  13. dondonner

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    Yes exactly. For definitive proof. See the two still images below - taken less than half a second apart. You can see the detail totally lost.

    In fairness grass is quite a difficult scene, there is a lot of fine detail everywhere so you would expect compression to struggle here but the way it drops out is pretty bad I think and if you start noticing it, you start to see it alot.

    http://i.imgur.com/JmXO6gQ.jpg
    http://i.imgur.com/6TZVIgC.jpg
     
  14. dondonner

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    OK turns out DJI are better at making quads than they are cameras...

    Lots of Inspire 1 owners complaining of the same thing as that also has a 60mbps bit rate and lots of compression artifacts.

    oh well. good drone for my use, just camera not ever gonna be great.
     
  15. windexh8er

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    The other thing to do is set WB and ISO to a manual stop - if it's flipping between either you can get the quick flip as is in your video at 0:03. I've noticed the auto ISO can generally be rather harsh...