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Heavy compression on video

Discussion in 'Inspire 1 Help' started by LitlBitl, Jul 13, 2015.

  1. LitlBitl

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    Hi fellow Inspire pilots!

    I have a question about I1 camera performance. Very often my footage contains very heavy compression artifacts - those awful square blocks appearing all over my movie. See the linked video below. Is this normal? Do you get sth like this as well? I don't get it always, but really very often, sometimes it is more pronounced than on other occasions. I'm trying to figure out if it is just the way Inspire camera works, or do I have a faulty unit?

    I record using LOG, 4k 25fps, all style settings at their defaults (sharpness, saturation, contrast - all at 0). My memory card is very fast (90 mb/s), so with 60 mb/s bitrate of Inspire camera that shouldn't be the problem.

    The video is full hd crop from 4k recording, focusing on the areas where the compression is especially noticeable.

    Any ideas?

    http://www.prokreacja.com/dji2.mp4
     
  2. InterMurph

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    First, that video is severely underexposed; according to the Premiere Pro waveform scope, the brightest parts are at 50%. Underexposed footage is noisier than properly-exposed footage. So whatever flaws this footage has are amplified by that.

    Second, when I played this footage in QuickTime Player on my Windows PC, it was very stuttery. When I played it back in Premiere Pro, it was smooth. So some of the problems you are seeing might be due to your playback method.

    And finally, I will say that my Inspire 1 footage never looks as bad as yours does. I am suspicious about what happened to it when you converted it from the original 4K to the HD footage you posted. What software did you use? What settings did you use to export the new file? The most obvious thing: when you divide the file size (282 million bytes) by the time (35 seconds), you get a bit rate of 7 megabites per second. That is very low, and is likely contributing to the problem.
     
  3. LitlBitl

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    I agree that the video is underexposed and thus noisier, but now I don't care about the noise, just the compression artifacts. I've done countless tests with different settings and such artifacts can appear anytime - with under/overexposed image, in auto/manual mode, no matter if TV is 1/50 or 1/5000.

    I agree that QuickTime cannot play those files well - but all other software I use (Premiere Pro, VLC, regular windows media player) can play the video smoothly, so it is just qt that fails here. And again, smooth playback is not an issue here.

    I agree that the video is not raw file from the camera - I had to make a quick edit to make it lighter - I wouldn't expect people to download 4gb file just to take a look. The key here is that the edit I made available looks the same as the source footage. I wouldn't post a file that doesn;t do justice to the problem I try to solve.

    I'm starting to think that it is indeed my camera that is faulty...