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• Extract Less Keyframes (ffmpeg)

  6 juillet 2019, par Barnee

  I’m trying to extract keyframes from a large video I have. The problem I’m seeing is that it is extracting far too many, leaving me with many very similar images.

  Below is what I am currently using (from terminal)

  ffmpeg -i video.mov -vf "select=eq(pict_type\,I)" -vsync vfr thumb%04d.png -hide_banner

  What would be great is if there was a way I can either make it only output 1 in 5 keyframes. Or what would be even better is if there is a way I can make it only output if the frame is over x% different from the previous one.

• How to link ffmpeg statically using mingw ?

  4 janvier 2017, par Iceman

  My application compiles success, but when run it can not find avcodec-57.dll, avdevice-57.dll and other ffmpeg libraries. I need a static app with no dependencies. Here is compiler’s log :

  cd 'D:\Projects\Test1'
  
  D:\Programms\MinGW\msys\1.0\bin\make.exe -f Makefile CONF=Release
  
  "/D/Programms/MinGW/msys/1.0/bin/make.exe" -f nbproject/Makefile-Release.mk QMAKE= SUBPROJECTS= .build-conf
  
  make.exe[1]: Entering directory `/d/Projects/Test1'
  
  "/D/Programms/MinGW/msys/1.0/bin/make.exe"  -f nbproject/Makefile-Release.mk dist/Release/MinGW-Windows/test1.exe
  
  make.exe[2]: Entering directory `/d/Projects/Test1'
  
  mkdir -p build/Release/MinGW-Windows
  
  rm -f "build/Release/MinGW-Windows/main.o.d"
  
  g++ -m32 -static -mwindows   -c -O2 -I/D/Programms/MinGW/ffmpeg/include -std=c++11 -MMD -MP -MF "build/Release/MinGW-Windows/main.o.d" -o build/Release/MinGW-Windows/main.o main.cpp
  
  mkdir -p dist/Release/MinGW-Windows
  
  g++ -m32 -static -mwindows    -o dist/Release/MinGW-Windows/test1 build/Release/MinGW-Windows/main.o -L/D/Programms/MinGW/ffmpeg/lib -lavdevice.dll -lavformat.dll -lavutil.dll
  
  make.exe[2]: Leaving directory `/d/Projects/Test1'
  
  make.exe[1]: Leaving directory `/d/Projects/Test1'
  
  
  
  BUILD SUCCESSFUL (time: 3s)

  (IDE : NetBeans ; Compiler : MinGW)

  Maybe I missed something ?

• automatically show blue screen in ffmpeg when live video source disconnects

  13 janvier 2015, par user1913115

  i’m capturing a live source using ffmpeg :

  ffmpeg -i rtsp://192.168.1.143/source -codec copy output.mp4

  which works great. the ip address is an address of an RTSP proxy server which takes in the camera itself as the source. i.e. my setup :

  camera ->> RTSP proxy ->> ffmpeg(output)

  if camera disconnects (accidentally or on purpose) the recording stops (obviously) and only continues when I re-connect the camera.

  Question : is there a way for ffmpeg to ’fill’ the down time with blue screen or green screen of some sort ?
  i know i can ’play’ a still image of a green screen using ffmpeg to record an mp4 out of it :

  ffmpeg -loop 1 -y -re -i green.jpg -r 30 -vcodec libx264 -an -f h264 greenvideo.mp4

  so i could set it up this way :

  ffmpeg(green) ->> ffmpeg(output)

  but I would need to run the command manually. is there a way for ffmpeg(output) to automatically detect the disconnect and use green.jpg as a ’video’ source ? or i can even create a 5-minute green.mp4 video of just green screen.

  put it another way, is it possible for ffmpeg to automatically switch input sources if one goes down ?