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Anyone else have aliasing on FPV preview with iPhone 5

Discussion in 'Phantom 2 Vision Discussion' started by helixaviator, Feb 22, 2014.

  1. helixaviator

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    I am using an iphone 5. The wifi stream is a bit disappointing even when close range and signal is very strong. There are parts of the image which are quite clear but then there are areas that look very pixelated. Is this normal? I attached a screenshot...maybe pixelated is not correct word. It sort of flickers?
     

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  2. Pull_Up

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    Re: clarity of wifi stream

    Hi. What resolution and frame rate have you got selected in the Settings section of the app?
     
  3. helixaviator

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    Re: clarity of wifi stream

    ok so it is 640x480 15fps
     
  4. Pull_Up

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    Re: clarity of wifi stream

    Any better at 30fps?
     
  5. helixaviator

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    Re: clarity of wifi stream

    here it is at 320x240 30fps...not much better.
     

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  6. Pull_Up

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    Re: clarity of wifi stream

    Difficult to know what you mean from the description and stills. Is it the whole image that's flickering? Do you mean the image drops in and out - or is it more just about the resolution of the preview image?
     
  7. helixaviator

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    Re: clarity of wifi stream

    hard to show with stills but if you look at the edges of the cabinets they appear wavy. In fact when it is streaming it actually looks like the eges are moving...waving and flickering etc.
     
  8. Pull_Up

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    Re: clarity of wifi stream

    That's an odd one. I use the android version of the app and haven't come across anything similar. It does the same when you're outside and flying I assume...
     
  9. iDrone

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    Re: clarity of wifi stream

    What you're seeing is aliasing. This happens when there aren't enough vertical and/or horizontal lines of resolution in the image acquisition, delivery, or display system. 640x480 should look fine on a phone, however if the wifi link is poor it will switch to lower quality in attempts to maintain delivery of video using lower bandwidth. As it gets worse it may drop resolution and/or start blocking, then eventually freeze and dropout completely.

    I've noticed many posts from users experiencing issues with iPhone 5 (I have a 4S and it looks fine). Edit the SUBJ line of your first post to something like: "Anyone else have aliasing on FPV preview with iPhone 5?" and hopefully others will come along to assist or share their experience & solutions.

    iDrone
     
  10. helixaviator

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    yep aliasing is exactly the word I was thinking. Happens with gaming on pc a lot. the strange thing is that the signal should be very strong as the extender phone and P2V are close to one another.
     
  11. Pull_Up

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    As iDrone said, it would be interesting to try your setup with a different flavour of iDevice, or even Android, and see what happens.
     
  12. helixaviator

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    yep...looks same on iphone 4s.....
     
  13. LeoS

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    Yeah, DJI's app currently does not apply any antialias filters, so each pixel shows up as a box even when our screen can display finer detail than 640x480. I hope they apply this in the future to smoothen out the jaggies.

    On the other hand, being a digital stream, the picture won't get visual interference as it moves further away; at least not the analog kind (flickers, rains, etc). It will start to get choppy (lower frames per second) until it completely blacks out\disconnected if it can't sustain the connection anymore.

    TL;DR: What you're seeing is low-resolution jaggies, completely normal.
     
  14. rich-s

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    Did anyone resolve this? My FPV was perfect initially. PV2 is about a month old. Last 2 days FPV looks like this. :(
    [​IMG]

    Not too much wrong with the camera as actual photo shows ok.

    [​IMG]

    Any help appreciated.
     
  15. helixaviator

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    never resolved it just learned to accept it. I am pretty happy with the picture/video quality but the wifi range on mine has been disappointing. Not to mention the stream quality with the aliasing.
     
  16. iDrone

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    You -should- be able to receive a perfectly good image up to the specified range for CE & FCC modes, especially if the camera's antennas are facing sideways (antennas are mounted in the sides) therefore facing you. Likewise the flat top of the Range Extender should be facing the Vision (its antennas are located under the top case).

    You could park it at one end of your block and walk to the other end so long as you have clear line-of-sight and no objects in between. Your picture should be as sharp as 640x480 can be on your device with no blocking or lower-quality downgrading of streaming video.

    If you're not getting that, its time to troubleshoot. Since the camera's FPV transmitter has two outputs, rotate the Vision 180° and face the other antenna on the camera towards you. Any improvement? If so, then your first output may be low, time to contact DJI and get the Camera's wifi transmitter fixed. If you've modded the camera to add an external antenna, open the camera and double-check your work.

    If not, then maybe its the Range Extender. If you've modded it to experiment with adding external antennas, open it and inspect your work. Look for antenna connectors popping off the board, pinched cables, or damaged cables at the base of the RP-SMA connector you added. When in doubt, replace the cable.

    Another possibility might be phone settings: hopefully your device (phone, tablet, pad) is configured properly and has a solid connection to the Range Extender and that's not the issue.

    I hope these suggestions help.

    iDrone :ugeek:
     
  17. helixaviator

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    your camera is great..beautiful picture.. looks very sharp.