[FFmpeg-user] video slows down in the middle

Henry Lau confiscate at gmail.com
Thu Feb 8 03:16:49 EET 2018

Hey guys, sorry I am not a full member of the ffmpeg alias group yet. Do I
have to be a member to receive responses? Just curious because it looks
like there is some interest in this thread.Thanks!

On Tue, Feb 6, 2018 at 4:19 PM, Henry Lau <confiscate at gmail.com> wrote:

> Hello,
> I tried to convert a Webm file to MP4. The output MP4 file is fine, plays
> normally at the start.
> But for some reason, in the middle it goes into "slow-motion".
> It then speeds back up to normal speed at the end.
> The screenshot below is when I view the output MP4 in QuickTime. At the
> bottom, you can see a "frame bar" (not sure what it's officially called).
> The middle part is the part where it slows down.
> [image: Inline image 1]
> Command I used to convert:
> ./ffmpeg -i inputWebm out.mp4
> The input video is here
> <https://drive.google.com/file/d/13zvEciv1Rq6aI-5LSt-9Fg-p2XC2rMOQ/view?usp=sharing>.
> The output is here
> <https://t.yesware.com/ta/fcc4dc28c3803f84e9fb06bb6730ebb57f2ea738/6c27f7a69a8bb8935ffe348f6d687c23/40629b4359c106c7424a7a7b899ab4a9?n=here&yta=https%3A%2F%2Fdrive.google.com%2Ffile%2Fd%2F1yymtHkUc2GcIBj2Fcboysird8YmppKWb%2Fview%3Fusp%3Dsharing>
> .
> Does anyone know why the output video slows down in the middle? Because
> when I view the input file, the "slow down in middle" issue does not happen.
> Thanks!
> Henry
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