VideoHelp Forum
+ Reply to Thread
Results 1 to 10 of 10
Thread
  1. firstly ,hello and apologies for such a strange first post.

    I have a rather unusual request, I would like a peice of footage and image analysed by folks here who think they may have an opinion on the occurrences in the material, specifically the anomaly to the subjects hand at exactly 4:27sec, importantly I would like to ascertain whether there is or isnt a technical explanation to the strange imagery, all of your expertise is appreciated.... if anyone wishes to give their opinions to me privately please request so.

    I know not everyone is an expert ,im just after opinions

    the image and video are below, please also note that this image lasts for less than a sec in the video before returning to normal, is there a technical explanation for this or is it unexplanable?




    Click image for larger version

Name:	bigger.png
Views:	484
Size:	110.3 KB
ID:	6574
    Last edited by quesioner101; 22nd Apr 2011 at 19:42.
    Quote Quote  
  2. This is common. It's macroblocking or error in encoding .

    There can be several reasons for why it occurs, the most common is insufficient bitrate

    It occurs in other places too, look at 1:18 for example.

    If we assume the source upload was ok, then it's likely from insufficient bitrate . I suspect it's more likely the source had those errors to begin with, this looks like a webcam capture

    YT re-encodes everything with a low bitrate . It uses long GOP encoding . The short explanation is differences between a certain keyframe (I frame) are coded and stored as P and B frames. When a bitrate limitation is imposed, there isn't enough bitrate to encode what the encoder is asking for, that causes these defects.
    Quote Quote  
  3. thank you 'poisondeathray, thats the most comprehensive opinion I have had one way or the other, could you also indentify whether you are a student or simply an enthusiast on subject of video ?

    and I welcome anyone else who also has this same opinion, do you all concur or perhaps you have a different opinion?

    thanks again for your input
    Quote Quote  
  4. In addition to the problems caused by too low a bitrate, I think there were some transmission problems (from the guy's webcam to the woman's computer). That caused some of the video frames to be lost and the picture to get corrupted.
    Quote Quote  
  5. thanks jagabo ,can we address what looks like a claw or talon so perfectly placed on his thumb, is this also a result of low bitrate ? are there two objects merging together to cause this look? how might this happen?
    Quote Quote  
  6. Yes, I think that particular problem was caused by data loss during the streaming of the webcam video via the video phone software. In the second or so before that frame you can see the picture freezes several times for several frames. That's an indication that frames were lost in the transfer. When the signal came back motion vectors* in the new frames moved the wrong parts of the image and the result is that odd claw.


    * With high compression codecs most frames do not encode the entire image but only the changes from frame to frame. Motion vectors can be used to tell the decoder to move blocks of pixels from one location in the old frame to a new location in the new frame. For example, if the camera was panning to the side, the encoded stream could say the equivalent of "move the entire picture to the left by 6 pixels, then add this 6 pixel wide vertical strip if new image to the right edge." That takes many fewer bytes than reencoding the entire new frame.

    It looks like the man's hand moved up into the dark area in the frames that were lost in transmission. When transmission was reestablished, motion vectors in the new frames moved blocks from where his hand should have been to the new location. But since his hand wasn't there dark blocks of background pixels were moved instead.
    Last edited by jagabo; 22nd Apr 2011 at 23:16.
    Quote Quote  
  7. thank you for your input, would you care to evaluate other footage of strange occurences ,I suppose what Im asking is ,would a technical problem be so varied, unpredictable and random that they would all fall under the same technical explanation every-time? or are there things which could not be explained under common technical terms..
    Quote Quote  
  8. Always Watching guns1inger's Avatar
    Join Date
    Apr 2004
    Location
    Miskatonic U
    Search Comp PM
    You are looking for anomalies, and are looking to interpret anything that you can't explain from your own knowledge as being supernatural in some way. Everything in that video image is easily explained by the low bitrate, poor transmission quality, and multiple re-encodings that are going on. Most of what you are experiencing is called Pareidolia, and is a side-effect of the way the human brain has evolved to work over time.
    Read my blog here.
    Quote Quote  
  9. Originally Posted by guns1inger View Post
    You are looking for anomalies, and are looking to interpret anything that you can't explain from your own knowledge as being supernatural in some way. Everything in that video image is easily explained by the low bitrate, poor transmission quality, and multiple re-encodings that are going on. Most of what you are experiencing is called Pareidolia, and is a side-effect of the way the human brain has evolved to work over time.
    I brought this video to this forum because I wanted third party advice and opinions, now if I thought this video was proof of somthing supernatural then this is the last place I would present them dont you think? I would be commiting suicide wouldnt I? ,instead I came here because I wasnt sure of what I was seeing so I came to a place where I might get an educated opinion which I got and am very thankful for, im not sure how you can see it any other way??
    Quote Quote  
  10. the below was helpful indeed, its easily understandable by the non techs

    It looks like the man's hand moved up into the dark area in the frames that were lost in transmission. When transmission was reestablished, motion vectors in the new frames moved blocks from where his hand should have been to the new location. But since his hand wasn't there dark blocks of background pixels were moved instead.
    Quote Quote  



Similar Threads

Visit our sponsor! Try DVDFab and backup Blu-rays!