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• Heroku ffmpeg buildpack

  20 octobre 2015, par Manuel Quintanilla

  Putting together the video upload section in my rails app and am having some issues with video play on mobile phones. Im using

  paperclip-av-transcoder, s3 and  Heroku

  On my laptop I can visit the page and see the video thumbnails and play the videos only because I have previously installed ffmpeg to my machine.

  Remotely on Heroku I’ve set the appropriate buildpacks for ffmpeg and have run push heroku master to install the buildpacks - Now when I visit the page on my mobile iPhone I don’t get a thumbnail but when I play the video it plays - on the other hand when I visit the page on my Android phone I don’t get a thumbnail and the video dose not play but I can upload mp4s on Android.

  Check out my set up here : Heroku ffmpeg buildpacks for video uploads

  It seems I don’t have the proper buildpack setup or some other heroku setting with ffmpeg.

  Any suggestions ? Thanks in advance !

• generate transparent video overlay or another way ?

  5 février 2016, par user2995705

  my src files are lots of pngs, and b.mp4

  What i want :
  overlay pngs (as anim) on b.mp4

  the way i have tried :
  the size of 200 pngs are almost 40M,could not put into the android phone..
  so I generate pngs to transparent video use this command :
  "ffmpeg -i %04d.png -vcodec png a.mov "

  then use
  "ffmpeg -i b.mp4 -i a.mov -vf overlay=0:0:0 out.mp4",
  it worked.
  but the problem I got is that the size of a.mov is too big (200 pngs,each file is 100k, a.mov is about 100M ),and i tried -vcodec copy,rawvideo,qtle,also got a very big file. are there any idea to resolve this problem ?

  then I tried to find another way:I generate pngs to mp4,use

  ffmpeg -i %04d.png -vcodec libx264 a.mp4

  and I know libx264 with yuv420p(libx264 not support yuva420p) could not keep the alpha channel ? but I still want to have a try.then I overlay a.mp4 on b.mov ;

  obviously,a black background under a.mp4 ....because it lost it’s alpha channel ?
  then I tried blend filter, I find blend=all_mode=lighten looks a bit same as what i want ?but it’s still not as same as the effect (overlay)

  any one who can help me ,thanks

• How to create a blank mp3 using ffmpeg ?

  11 mai 2017, par Vrushank Upadhyay

  I have built ffmpeg for android by using android NDK. I am using cocos game-engine to compile and run the project. I want to create a blank mp3 of lets say 20 seconds when a button is pressed. I have tried almost everything. The following command generates an output file but it is of 0 bytes.

  ffmpeg -f lavfi -i anullsrc=r=48000 -t 20 -codec copy /sdcard/output.mp3 

  My ffmpeg configuration is :

  > ./configure \
  
  >     --prefix=$PREFIX \
  
  >     --disable-network \
  
  >     --disable-doc \
  
  >     --disable-ffplay \
  
  >     --disable-ffprobe \
  
  >     --disable-ffserver \
  
  >     --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" \

  Any help would be appreciated. I am testing this on an android phone. I have built static libraries for ffmpeg and they are linked to the project.