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I converted an avi file to mp4 using ffmpeg:

ffmpeg -i video.avi video.mp4

The resulting file I got is encoded using H264 but the video is flawed

This is the source AVI file (5 MB): [link redacted]

This is the resulting MP4 file (20 KB): [link redacted]

Does this defect have a name? The words that come in my mind is tear, tearing, bleed, bleeding, and melting - because the dark colors "fall" down.

Metadata - Video: MPEG4 Video (H264) 640x360 25fps 27kbps [V: h264 high 4:4:4 predictive L3.0, yuv444p, 640x360, 27 kb/s]

This is a screenshot of the video:

enter image description here

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  • 1
    post some screenshot of single frames instead of links to the whole file, please. Also, metadata on bitrate and bit depth might be useful.
    – 1NN
    Dec 16, 2021 at 11:39
  • The defect is called a bad encoding. No way that a 5 MB video can be encoded into only 20 KB.
    – harrymc
    Dec 16, 2021 at 11:48
  • 2
    Well that really depends. If the 5 MB AVI file is uncompressed and just a static image, it is possible. // What is the exact resolution of the source file?
    – Daniel B
    Dec 16, 2021 at 12:17
  • 3
    Looks like a bug in the player when processing motion compensation.
    – dirkt
    Dec 16, 2021 at 13:25
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    I've redacted the links as they opened unwanted and potentially harmful popups. Questions should be self-contained. If linked material is needed, make sure that your links open directly the needed content, without any popups, advertising or anything similar. Thank you.
    – 1NN
    Dec 16, 2021 at 13:52

1 Answer 1

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It's a rendering issue, not an issue of your video file. Use a different video player or update your codec library and your video player. This is a screenshot on my system:

enter image description here

MPC-HC is a discontinued player, although on my system it renders fine. But if you are having issues with it, use VLC or something else.

To answer your question, there's no name for such defect, as it's not a video defect. It's impossible to say where on your system the problem arises.

EDIT: In light of dirkt 's comment, here's a possible explanation:

Motion compensation block boundary artifacts

Block boundary discontinuities can occur at edges of motion compensation prediction blocks. In motion compensated video compression, the current picture is predicted by shifting blocks (macroblocks, partitions, or prediction units) of pixels from previously decoded frames. If two neighboring blocks use different motion vectors, there will be a discontinuity at the edge between the blocks.

Source: Wikiwand.com

So, it can be that your player can't handle the discontinuity between the blocks in a sensible way.

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  • Indeed, I opened the file in VLC and it works. Yet I can use a screen capturing program to record the MPC-HC playing it and to save it in a video with defects. By saving the same (Avisynth) source directly from Virtualdub2 in MP4, I get the same size, therefore the encoded size is small but realistic.
    – Joe Jobs
    Dec 16, 2021 at 15:16
  • The screenshot is messed up in a way that can occur with bugs in BitBlt (ahem, probably not bit granular, so just plain bitting/copying of memory). As if they decided to a copy where source and dest overlap (eg if there was an animation effect (starting at the wrong end). Which can happen with broken coordinate arithmetic, possibly only at certain display/window sizes.
    – Krazy Glew
    Dec 17, 2021 at 0:11

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