(Note: the video is a screencast hence the desktop icons, that's not actually the desktop of the machine having the error.)

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We are using JWPlayer, and we rarely have this issue, but on it is frequently reported by customers and becoming a repeat issue. We've had them update their Flash player to the latest version. What causes this? My guess is codecs or video driver issues but I am not sure how to fix.

  • 1
    ".mp4" doesn't tell us anything about the codec. (See this question, asked just recently.) Sep 12, 2011 at 21:59
  • Does the problem go away when a keyframe pops up? I've seen this quite a bit, always due to video corruption. The problem should go away on the next keyframe. If it doesn't, something else is likely wrong.
    – Brad
    Sep 13, 2011 at 16:40
  • @leftaroundabout sadly I don't know anything about the codec, but I was curious to know if it might be a codec issue
    – MetaGuru
    Sep 13, 2011 at 20:44
  • You can see what codec it is when you open it in, for instance, VLC. Sep 13, 2011 at 20:48

2 Answers 2


Put keyframe distance in the encoding options to KEY EVERY FRAME.

When you export in the export options you have keyframe distance, which is used to calculate "intermediate key points/key frames", and the default is 25/30 frames. The player calculates pixels and frames inbetween keyframes. Sometimes it gets lost in calculation because of lost bits or bytes. Having less distance between keyframes reduces the chance of this, and results in more accurate frame rendering.

  • I've edited your comment into your answer (and removed our now-outdated comments), so that the answer is much clearer. In general this is a better place to put explanation, since it's easier to read and the comments aren't really "part" of the answer anyway - just associated with it. If I've made any error, please do edit the question to fix it. Oct 27, 2011 at 17:45

This has nothing to do really with Codec. Even if the stream is fully corrupt, the media player needs to portray only such things within the UI window.

This could be most likely a device driver or software dependency with player having issue. try alternative players.

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