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• node.js live streaming ffmpeg stdout to res

  24 mai 2014, par blasteye

  I want node.js to convert an extremly long audio file to mp3, and the second data is available on stdout, node.js should send it to the client for them to play.

  I’ve written the following, and while it works, the html5 audio/video tag waits until ffmpeg is 100% done transcoding, where-as I want to start playing the video while ffmpeg is doing its thing.

  var ffmpeg = childProcess.spawn('ffmpeg', [
  
     '-i', params.location, //location of the specified media file
  
     '-f', 'mp3',
  
     'pipe:1'
  
   ]);
  
   res.writeHead(200, {
  
     'Content-Type': 'audio/mp3'
  
   });
  
   ffmpeg.stdout.pipe(res);

  EDIT 1 : Not sure why, but if params.location points to a movie everything seems to work. But if its an audio file, ffmpeg doesn’t seem to be outputting to stdout until its 100% converted.

  EDIT 2 : Turns out that you can’t dump an mp4 file to stdout due to the fact that mp4 files are non Causal (http://en.wikipedia.org/wiki/Causal_system). THerefore if you use webm it works. Just make sure to compile ffmpeg with webm support (for homebrew users : brew install ffmpeg —with-vpx —with-vorbis ).

  I’ve uploaded a github gist showing two functions to send live mp3/webm transcodes : https://gist.github.com/cobookman/c1a9856a4588496b021a

• Skipping incompatible libmp3lame.a while searching mp3lame (FFMPEG)

  19 octobre 2014, par trololo

  I want to compile ffmpeg with libmp3lame for my Android app. I’m using Virtual Machine with OS Debian.
  While compiling I recieve with message in Console.log file :

  skipping incompatible /home/sla/ffmpeg_build/lib/libmp3lame.a while searching mp3lame
  ...

  That’s why compilations doesn’t work properly.

  I’ve installed lame for debian using this code install.sh :
  (https://trac.ffmpeg.org/wiki/CompilationGuide/Ubuntu)

  sudo apt-get install libmp3lame-dev
  
  mkdir /home/sla/ffmpeg_build
  
  mkdir /home/sla/ffmpeg_sources
  
  sudo apt-get install nasm
  
  cd /home/sla/ffmpeg_sources
  
  wget http://downloads.sourceforge.net/project/lame/lame/3.99/lame-3.99.5.tar.gz
  
  tar xzvf lame-3.99.5.tar.gz
  
  cd lame-3.99.5
  
  ./configure --prefix="/home/sla/ffmpeg_build" --enable-nasm --disable-shared
  
  make
  
  make install
  
  make distclean

  But it doesn’t work (lame compiles but ffmpeg - doesn’t).
  ffmpeg compiler says something strange.

  For ffmpeg I wrote flags :

  --export-cflags
  
  -I/home/sla/ffmpeg_build/include
  
  
  
  --export-ldflags
  
  -L/home/sla/ffmpeg_build/lib

  How to fix it ?

• How to modify this Windows script to do a match ?

  21 janvier 2016, par Andrei Clear

  ffmpeg can resize a video/image file .. first is input_file .. parameters .. output_file ..

  ffmpeg -i input.avi -vf scale=320:240 output.avi

  or

  ffmpeg -i 20140724_071746.mp4 -vf scale=640:-1 20140724_071746_LOW_640.mp4

  more info here : https://trac.ffmpeg.org/wiki/Scaling%20%28resizing%29%20with%20ffmpeg

  I want it to downscale all the videos on my microSD card to create space (I have originals backed-up)

  So I want it to go throw all the files in all the sub-directories overnight and resize all the files. Chances are that the script might stop or crash and I would need to run it again, or if I add new files I would want to run it again.

  So I would want it to skip processing all the files that have been processed AND their resized versions.

  In my case if a FILE_NAME.mp4 also has FILE_NAME_LOW_640.mp4 SKIP it
  AND
  if a FILE_NAME_LOW_640.mp4 has *640 SKIP it

  Here is my Windows batch script so far

  REM @echo off
  
  REM just save as "DOS"
  
  REM cd /d C:\s
  
  
  
  setlocal enabledelayedexpansion
  
  for %%j in (*.mp4) do (
  
  set filename=%%~nj
  
  echo %%j
  
  
  
  ffmpeg -i %%j -vf scale=640:-1 %%j_LOW_640.mp4
  
  
  
  REM but now I want to add the two checks to skip files that have been resized .. or if they are the resized version 
  
  
  
  REM if not "!filename!"=="%%j_LOW_640.mp4" AND IF FILE !COINTAIN *640* THEN ffmpeg -i %%j -vf scale=640:-1 %%j_LOW_640.mp4
  
  
  
  )
  
  
  
  pause
  
  REM AND I would also want it to process all the sub-directories  

  In other words my questions for help are :

  1. How can I do a check for a string if it contains a string match ?

  2. How can I have my script also process all the subdirectories ?