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• How to cheaply "undo" a mosaic (i.e. split an image into halves or quadrants) with ffmpeg ?

  5 mars 2020, par John Allard

  FFMPEG makes it easy to take multiple inputs and stack them into a mosaic video. I am looking for a way to do the opposite, specifically I would like take a video stream that is composed of four streams stacked into quadrants and split it into four separate videos consisting of the coordinates

  video1 = [0, 0.5*w, 0, 0.5*h]
  
  video2 = [0.5*w, w, 0, 0.5*h]
  
  video3 = [0, 0.5*w, 0.5*h, h]
  
  video4 = [0.5*w, w, 0.5*h, h]

  I know that I can do this with four separate ffmpeg calls using the crop filter but this seems to be unnecessarily expensive. Is there a way to do this in a single call ?

• Add .mailmap

  22 février 2020, par Josh de Kock

  Add .mailmap
  This allows for easy shortlog/log parsing, useful in determining
  
  eligible members of the general assembly for the new FFmpeg voting
  
  system.
  Signed-off-by : Josh de Kock <josh@itanimul.li>
  

  • [DH] .mailmap

• Error on building ffmpeg for android using NDK in ubuntu

  17 février 2015, par Alin

  ---

  An ffmpeg android for android 2.3+ which allows me to decompress/add watermark/recompress a video file. I need to have it working on all current CPUs.

  What I did so far

  I looked in a lot of sources for guidance. Most of the articles are obsolete or simply not work. Not to mention the whole struggle I went to from installing ubuntu on virtualBox, an OS which I never seen before. The whole java/sdk/ndk install was pretty easy but I had hard times in setting the PATH variables and most importantly WHERE to set them.

  So, here is my structure :
  The default folder path is /home/alin in which I have
  

  The PATH is set in etc/profile and I can confirm that it works. I know that it works because running java -version or ndk-build run just fine

  > ANDROID_SDK=/home/alin/android/sdk ANDROID_NDK=/home/alin/android/ndk
  
  > JAVA_HOME=/usr/local/java/jdk1.8.0_20
  
  > PATH=$PATH:$HOME/bin:$JAVA_HOME/bin:$ANDROID_SDK/platform-tools:$ANDROID_SDK/tools:$ANDROID_NDK
  
  > export JAVA_HOME export ANDROID_SDK export ANDROID_NDK export PATH

  I have downloaded the latest sources from ffmpeg.org and saved it in ndk/sources folder, in sources I have created an android_build.sh file as from (http://www.roman10.net/how-to-build-ffmpeg-with-ndk-r9/)

  

  #!/bin/bash
  
  
  
  NDK=/home/alin/android/ndk
  
  SYSROOT=$NDK/platforms/android-9/arch-arm/
  
  TOOLCHAIN=$NDK/toolchains/arm-linux-androideabi-4.8/prebuilt/linux-x86_64
  
  
  
  function build_one
  
  
  
  {
  
  
  
  ./configure \
  
      --prefix=$PREFIX \
  
      --enable-shared \
  
      --disable-static \
  
      --disable-doc \
  
      --disable-ffmpeg \
  
      --disable-ffplay \
  
      --disable-ffprobe \
  
      --disable-ffserver \
  
      --disable-avdevice \
  
      --disable-doc \
  
      --disable-symver \
  
      --cross-prefix=$TOOLCHAIN/bin/arm-linux-androideabi- \
  
      --target-os=linux \
  
      --arch=arm \
  
      --enable-cross-compile \
  
      --sysroot=$SYSROOT \
  
      --extra-cflags="-Os -fpic $ADDI_CFLAGS" \
  
      --extra-ldflags="$ADDI_LDFLAGS" \
  
      $ADDITIONAL_CONFIGURE_FLAG
  
  
  
  make clean
  
  make
  
  make install
  
  }
  
  
  
  CPU=arm
  
  
  
  PREFIX=$(pwd)/android/$CPU 
  
  
  
  ADDI_CFLAGS="-marm"
  
  
  
  build_one

  When running the .sh file I get this :
  

  Trying different build.sh sometimes I got different errors... so I have no idea what to do next.

  Please guide me to :

  • be able to build ffmpeg
  • make it compatible with as many devices as possible.

  Thank you.