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• Programatically add a simple pause to a video

  8 mai 2020, par gota

  Say I have a 30s video. I want to produce a 40s video that is just the first video but with an extra "freezed" frame (for say 10s) somewhere in the middle of it. (think of it as wanting to comment the video at a specific point)

  



  I know I can do this easily with video editing software. However, I am looking for a command line tool that allows me to do this efficiently (I need to do this several times with variable points to freeze the video)

  



  I am using Python

  



  I thought of using ffmpeg, splitting the video into two, creating a third video composed of a given frame, and then concatenating the three videos.

  



  But maybe there is a much simpler technique ?

  


• 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.

• FFMPEG - Adding a full-frame image to the beginning of a video

  17 janvier 2020, par lyinawake

  I have tried many different ways to try to create a 10 second video file out of an image file and have used all the same switches and codecs as I used to encode my video file. However, when I concat the two using anything but complex_filter (which forces the video through another round of transcoding), the resulting video file is corrupt. I believe this is due to the inherent differences of the 10 second clip that ffmpeg created from the image, but there must be some way to get it to encode the exact same way as my video file.

  Here is the command I am using to turn the image into a 10s video clip (I added a silent mp3 because I thought that an audio stream starting partway through the video was messing things up) :

  ffmpeg -loop 1 -i splash.jpg -i silence.mp3 -c:v libx264 -preset slow -g 60 -r 29.97 -crf 16 -c:a libfdk_aac -b:a 256k -cutoff 18000 -t 5 tmpoutput1.mp4

  Here is the command I am using to encode my video :

  ffmpeg -i input.f4v -c:v libx264 -preset slow -g 60 -r 29.97 -crf 16 -c:a libfdk_aac -b:a 256k -cutoff 18000 tmpoutput2.mp4

  Here is the command I use to convert both of them to .ts to get ready for concat :

  ffmpeg -i tmpoutput1.mp4 -c copy -bsf:v h264_mp4toannexb -f mpegts tmpoutput1.ts

  And finally the concat (which is where I get crazy video corruption, everything along the way looks fine) :

  ffmpeg -i "concat:tmpoutput1.ts|tmpoutput2.ts" -c copy output.mp4

  Again, the issue is that I’m already transcoding everything once and I should be able to get it to transcode in a similar enough structure so that it can be concatenated without another transcode tacked onto the end.

  Has anyone successfully added a full-frame splash graphic to the front of a video with ffmpeg before ? I am using a brand new cross-compile of ffmpeg as I thought that might be the issue, but alas, the issue persists after the update.

  Thanks !