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• FFmpeg - How to trim with high precision ?

  11 octobre 2016, par DSalenga

  I am pretty stucked with the way that FFmpeg trims videos, so I would be really grateful if someone could help me.
  Basically, what I am trying to do is : I have a video sequence and I want it to stop in a certain second, freeze the image some seconds (like a pause), and then reproduce again from the same exact frame. I could say that I am dealing with three videos : A.mp4 (first part of the video sequence), B.mp4 (frozen image) and C.mp4 (second part of the video sequence). Besides, I also perform an overlay with filter_complex.

  The part of generating a video from a static image is not a problem, my main concern is to find the way to trim and concatenate videos accurately. From other posts and sources, I discovered that FFmpeg trims from those Frames that are Keyframes, which can be forced. However, the result I obtain is not the appropriate one, because my video A ends in a frame different from the one in the beginning of C.

  The commands I am using are the following ones :

  ffmpeg -y -i VideoSequence.mp4 -c:v libx264 -pix_fmt yuv420p \
  
  -force_key_frames "expr: gte(t,n_forced * 15)" -t 30 VideoOut.mp4

  [Note that everything inside Filter Complex is about an Overlay, which works fine]

  As far as I know, the resulting video should have a Keyframe every 15 seconds. Now, I want to cut the video into 2 parts ("before second 15" and "after second 15") :

  ffmpeg -y -ss 00:00:01 -i VideoOut.mp4 -t 14 -c copy A.mp4
  
  
  
  ffmpeg -y -ss 00:00:15 -i VideoOut.mp4 -t 5 -c copy C.mp4 

  As mentioned, I expect the end of A.mp4 to "match" with the beginning of C.mp4 (at a frame precision), but the result I obtain is far from being perfect.

  Thank you very much, any kind of help will be appreciated !

• re-stream other stream with niginx software

  14 avril 2015, par PieterPost

  Goodday everybody,
  I have question about Nginx streaming software and the resteaming from other streams.
  I wanne restream another stream (third party) with nginx because this way I wanne create so called thumbs from the (third party) stream and stream it on my own site .
  The thumbs part is what I all know , the part of the restream is the unkown part for me .
  Long story short now .
  1. The stream link what I like restream is

  http://154.57.145.83/flv/5285079c2c9e5/testat123.flv

  As out going stream on my site I wanne have it like :

  rtmp ://145.44.194.308:1935/myapp/flv:test.flv

  I have found this like on stackoverflow as well but it haven’t help me out so far . (How to restream an udp live stream using nginx rtmp module ?)

  This is my code what I have used and dont seems to work .

  exec_pull ffmpeg -i
  http://154.57.145.83/flv/5285079c2c9e5/testat123.flv -c:v libx264 -c:a
  libfaac -ar 44100 -ac 2 -f flv rtmp ://145.44.194.308:1935/myapp/test ;

  So I hope someone here can help me out because I think other people will like to do same thing as well

  Greatings and have yourself an great day

• How to concatenate two or more videos with different width in FFMpeg and to maintain the same aspect ratio ?

  23 octobre 2019, par Aarwil

  I have five video parts to concat all. Each five videos are in the same width and height. The second part is the hstack of another 2 videos and the third part is the hstack and vstack of another 3 videos. While concat all the five video parts the aspect ratio is not maintaining in the final video. Since I am new to ffmpeg help me to sort out the problem

  I have tried with the command with filter complex and to reduce the size I used frame per second.

  "ffmpeg -i
  RM356ce8c15f47cb07b7af885fd718a39f/final/RM356ce8c15f47cb07b7af885fd718a39f.mp4 -vf scale=1280:480 -filter:v fps=fps=30 E :\test\routes\public\assets\downloads\RM356ce8c15f47cb07b7af885fd718a39f/final/RM356ce8c15f47cb07b7af885fd718a39f.mp4"

  Only ’-vf fps=fps=30’ read, ignoring remaining -vf options : Use ’,’ to separate filters