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• Convert MP3 bitrate from a stream into another stream with ffmpeg

  10 juillet 2013, par Léon Pelletier

  Using ffmpeg, I would like to know if it's possible to convert mp3 bitrate as data chunks are received ?

  That means I would send slowly chunks to ffmpeg so that it outputs a mp3 with another bitrate.

  So in very-pseudo-code, it looks like it :

  1. MP3 Request from user

  2. Send the default mp3 to ffmpeg with parameters to convert to the desired bitrate.

  3. As it's writing a new file, write what as been writen so far in the Response outputstream (I'm in ASP.Net)

  Is that feasable or I need to switch to another technology ?

  [EDIT]

  For now, I'm trying a solution like this : Convert wma stream to mp3 stream with C# and ffmpeg

  [EDIT 2]

  I answered my question, and it is feasible with an url as input and standard output as output. Using an url allows to process a file chunk by chunk, and using stdout, we can access data while it is processed.

• Bambuser ffmpeg - "arm-linux-androideabi-gcc is unable to create an executable file."

  14 avril 2014, par Chaitanya Chandurkar

  I know this may be possible duplicate of some questions. but answers for those threads are not helping me.

  I am trying to compile ffmpeg library for android using Bambuser's ffmpeg.
  I downloaded Archive for client versions 1.3.7 to 1.6.0. from bambuser.

  I followed instruction given in REAME.
  While running ./build.sh i came across following error

  arm-linux-androideabi-gcc is unable to create an executable file.
  
  C compiler test failed.
  
  
  
  If you think configure made a mistake, make sure you are using the latest
  
  version from SVN.  If the latest version fails, report the problem to the
  
  ffmpeg-user@mplayerhq.hu mailing list or IRC #ffmpeg on irc.freenode.net.
  
  Include the log file "config.log" produced by configure as this will help
  
  solving the problem.

  Here are last few lines of config.log of ffmpeg

  mktemp is /bin/mktemp
  
  check_ld
  
  check_cc
  
  BEGIN /tmp/ffconf.qflVj27Q.c
  
      1   int main(void){ return 0; }
  
  END /tmp/ffconf.qflVj27Q.c
  
  arm-linux-androideabi-gcc --sysroot=/home/chaitanya/android/android-ndk-r5b/platforms/android-8/arch-arm -c -o /tmp/ffconf.gc6um0Ki.o /tmp/ffconf.qflVj27Q.c
  
  arm-linux-androideabi-gcc: error trying to exec 'cc1': execvp: No such file or directory
  
  C compiler test failed.

  in tmp i do not find any relative folder or file as per config.log says "ffconf.qflVj27Q.c".

  I am doing this on
  1. Ubuntu 11.10
  2. OpenJDK 6
  3. android-ndk-r5b

  NOte :
  I only have API-10 Installed in eclipse. (if it matters :D)

  What could be the solution for this ?

• How to use ffmpeg / x264 2-Pass encoding for multiple bitrate output files

  2 décembre 2014, par Jonesy

  While performing a 2-Pass encode to multiple output files I was receiving the error

  ratecontrol_init: can't open stats file 1 ffmpeg2pass-2.log

  My setup is to do a single first pass and then multiple second pass encodes to output files with different target bitrates using the same first pass results.

  ffmpeg -y -i $INPUT_FILE -an -vcodec libx264 -pass 1 -b:v 700k -f rawvideo /dev/null
  
  
  
  ffmpeg -y -i $INPUT_FILE -i out-aud.mp4 \
  
  $AUDIO_OPTIONS_P2 -vcodec libx264 -pass 2 -b:v 250k -f mp4 out-250.mp4 \
  
  $AUDIO_OPTIONS_P2 -vcodec libx264 -pass 2 -b:v 500k -f mp4 out-500.mp4 \
  
  $AUDIO_OPTIONS_P2 -vcodec libx264 -pass 2 -b:v 700k -f mp4 out-700.mp4

  This sequence resulted in the error listed above. What I discovered thru code-inspection is that ffmpeg/x264 looks for a different set of first-pass files for each second-pass encoding path. The first encoding path uses the set of files originally created

  ffmpeg2pass-0.log
  
  ffmpeg2pass-0.log.mbtree

  The second encoding path requires first-pass files with the names

  ffmpeg2pass-2.log
  
  ffmpeg2pass-2.log.mbtree

  The third encoding path requires first-pass files with the names starting with ffmpeg2pass-4*, etc.

  My solution was to create soft-links to the originally created set of files with the new names that were required for each pass before running the second-pass command.

  ln -s ffmpeg2pass-0.log ffmpeg2pass-2.log
  
  ln -s ffmpeg2pass-0.log.mbtree ffmpeg2pass-2.log.mbtree
  
  ln -s ffmpeg2pass-0.log ffmpeg2pass-4.log
  
  ln -s ffmpeg2pass-0.log.mbtree ffmpeg2pass-4.log.mbtree

  This seems to work as it results in the output encodes that I needed. However, I don’t know if this method is legitimate. Am I getting sub-optimal encoding results by using a first-pass output for one bitrate (700k) as the input to second-pass encodings for other bitrates ?