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• Application memory usage decrese

  17 septembre 2018, par unresolved_external

  I have an application which actively uses ffmpeg for video decoding. The interesting thing which I discovered, is that after some time(hour or two) the memory usage is decreasing for about 20-25%. (e.g. from 260Mb to 200 Mb). I am wondering if this due to some specifics of the ffmpeg implementation ? Or maybe this kind of memory fluctuations can happen if the memory is used actively.

  I am running on x86_64 Ubuntu. The compiler is clang with libc++.

• PHP FFmpeg video aspect ratio problem

  18 mai 2013, par Herr K

  i compiled the new version of FFMPEG and the padding commands have been deprecated.
  As i try to get familiar with the new -vf pad= commands, i want to ask, how can i
  convert a video without changing it's aspect ratio.

  I've checked numerous solutions from stackoverflow, nothing seemed to work.
  Can someone, please post a working PHP example or cmd line. I would be VERY happy.

  Please note that the videos in question, could be 4:3 and also be 16:9

  Let's say, i convert a 16:9 video to 640x480 format. It will need some bars at
  the top and at the bottom. That is what i want to do.

  Thanks

• splitting mp4 files with ffmpeg

  25 février 2015, par user2410624

  I have a 2-hour long mp4 video file with no audio. I want to extract a 15-minute portion of this video. The catch is that I want to add a fade-in to the beginning and a fade-out to the end without having to re-encode the entire thing. My thought is that I could extract 3 portions as follows :

  First Portion - First second of 15-minutes :

  ffmpeg -i input.mp4 -ss 1200 -t 1 -vcodec copy out1.mp4

  Second Portion - Between the first second of video and the last second of video :

  ffmpeg -i input.mp4 -ss 1201 -t 898 -vcodec copy out2.mp4

  Third Portion - Last second of 15-minutes :

  ffmpeg -i input.mp4 -ss 2099 -t 1 -vcodec copy out3.mp4

  Then I want to use ffmpeg to add a fade in to out1.mp4 and a fade out to out3.mp4. Then finally use ffmpeg to concatenate the 3 portions together.

  So here are my questions :

  1. Just getting the first portion extracted is causing me problems. It seems to only extract one frame of black. (There are no black frames in this 1 second portion.) I was expecting to get 1 second of video exactly as it is at the 1200th second of the video file. I thought I even read that extracting at the I-frames is preferable, but even that (with the assistance of ffprobe) isn’t getting me the portion I’m expecting. This is an example of that command :

     ffmpeg -i input.mp4 -ss 1200.143678 -t 1.1101 -vcodec copy out1.mp4

  Am I misunderstanding the capability ? Am I doing the command wrong ? Are my mp4 files bad ? This file is 1080p. I tried the same thing with a 360p version of the file and for some reason it worked. Not sure why.

  2. My other question is, am I taking the best approach to achieve what I want to achieve. Which is : taking a 15-minute mp4 video out of a 2-hour mp4 video and adding a fade up and fade down in such a way that I don’t have to re-encode the entire 15 minutes. Is this doable ? Anyone have any good suggestions for the best way to do this ?

  Thanks.