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Maybe this is a dumb question, but when I run a test render on the first 100 frames or so everything looks great - renders in HD to H.264 in MPEG-4 with H.264 codec and MP3 audio codec, everything in the sample render looks and sounds like I want it to. However, when I extend the end frame to the full video length (31,049 frames) the resulting mp4 file won't play anything in VLC media player or Windows Media Player.

I'm not sure why the short render works but the long one doesn't? The only thing I'm changing between renders is the end frame.

For reference, I'm on Windows 10 using Blender 2.76b. I'm by no means a power user, but it seems that whether I render using my CPU or my GPU I end up with the same thing - short render gives me a good result, but long render won't play for anything.

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  • $\begingroup$ If you render at 25% or even lower does it work? The only thing I can think of the is the resulting file size. When you say VLC will not play it, does it open it and what does the Codec information window say regarding the video format, size, width,height, length, bit rate etc? $\endgroup$
    – rob
    Jan 24, 2019 at 10:35
  • $\begingroup$ Thanks for your reply. I haven't done a lower fidelity render like 25%. The file size is 914 MB, but the Codec information in VLC isn't showing any details - it's almost like it doesn't recognize the file at all. Is it possible that I've made it too big for VLC? I've used it for playing back movies before and I imagine that those would be bigger than my silly little video. Do you think I ought to reduce the bitrate to make the file smaller or something? $\endgroup$
    – BS1441
    Jan 24, 2019 at 12:26
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    $\begingroup$ I was looking for the 4Gb limit AVI files have, so its not that. VLC is normally really good at reading video files and giving information even if it does not play correctly. It should not matter but is the .MKV or .MP4 or nothing? I would also recommend using a non MP3 audio codec. MP3 seems like the obvious choice but I think AAC is more common/compatible. Worth trying with no audio to test. $\endgroup$
    – rob
    Jan 24, 2019 at 13:05
  • $\begingroup$ .mp4 is the extension on the final file. I'll give it another shot with the AAC to see if that changes anything. Thanks for your time so far. My other plan is to render in 2 phases - first render into smaller videos that seem to be working fine, then take each of those videos and stitch them together. Any reason to think that will be more stable? It'll end up the same length overall but IDK maybe the first round of rendering will simplify things by turning all the strips into one video and one audio... $\endgroup$
    – BS1441
    Jan 24, 2019 at 23:58
  • $\begingroup$ Blender uses an out of date copy of the FFMpeg library internally and it has some odd issues that have been fixed elsewhere. I often just run the Blender videos through ffmpeg console application just to get a "clean" version. ffmpeg -i yourfile.mkv -c:v libx264 -crf 23 -pix_fmt yuv420p -c:a copy -r 24 newfile.mkv $\endgroup$
    – rob
    Jan 25, 2019 at 11:46

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The command mentioned by rob helped to fix my .mp4 video

Thanks, rob

I used ffmpeg -i yourfile.mp4 -c:v libx264 -crf 23 -pix_fmt yuv420p -c:a copy -r 24 newfile.mp4

Before running the command you should:

  1. Make sure that you installed ffmpeg
  2. And added the bin folder where ffmpeg.exe is to your PATH variable if you using Windows

To run the command:

  1. Go to folder with the video and copy its path, for example (C:\Videos\Blender)
  2. Now press Win+R to open Run menu and type there cmd.exe and pres OK. It should open a console window
  3. Type there cd (space) and paste the path to folder, for example (cd "C:\Videos\Blender") and press enter
  4. And finaly paste ffmpeg command I mentioned erlier with your file names and wait untill it finihed

cmd running command example

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