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• SOLVED - Compiling FFMPEG on Windows with Cywin and NDK r5

  19 mai 2012, par protectedmember

  This isn't a question - it's an answer for alll of you who have been facing the same problems as I have. I've been trying to compile this thing for a while now and I know of the numerous posts floating around the internet offering help. I have read and tried most of the suggestions and wanted to colate my success into this single post for others to benefit from.

  Since I don't have a blog, I thought it wouldn't hurt to post on here instead.

  I have managed to compile FFMPEG 0.10.3 (Freedom) on Windows 7 (32 bit) using NDK r5 and Cygwin. The steps :

  1 - Download/install Cygwin in the root of your C drive. I'm not going to give instructions on this, it's simple enough and there are plenty of tutorials on this.

  2 - Download NDK r5 from here and extract to the root of your C drive.

  3 - Download FFMPEG 0.10.3 from here and extract to the root of your C drive.

  4 - Open the file 'configure' in the root of the FFMPEG directory in a text editor.

  5 - Comment out lines 2073, 2074 and 2075.

  6 - Below 2075, add the following line :

  TMPDIR=c :/cygwin/tmp

  7 - Download this script (thankyou roman10) and place it inside your FFMPEG root directory. Rename the file to

  build_android.sh

  8 - Open the script in a text editor and edit line 17 to read

  c :/android-ndk-r5

  9 - Click start > run and type "bash" (without the speech marks) and press enter.

  10 - Type the following and press enter :

  cd /cygdrive/c/ffmpeg-0.10.3

  11 - Type the following and press enter :

  ./build_android.sh

  12 - Sit back and wait... libffmpeg.so will soon appear in your "c :\ffmpeg-0.10.3\android\" directory (where is defined in the bottom of the script from roman10's blog). The default architecture is armv7-a.

  The script from roman10's blog will actually compile quite a large shared object (.so) file. The compiler flags can be adjusted to suit your needs in the script from roman10's blog.

  I hope this helps,

  P.

• How to set time_base when muxing AVI with libavformat ?

  18 mai 2012, par Anastasia

  In my application I receive from a remote server synchronized video
  (mpeg4) and audio (mp3) and mux them to avi file. The video comes
  frame-by-frame, and the audio comes in small chunks, say 200-250 ms.
  Both video frames and audio chunks have timestamps in milliseconds.

  My question is how to set audio time_base and pts correctly ?
  For video I set time_base.num = framerate, time_base.den = 1 ; and
  calculate pts as follows :

    AVRational time_base_1kHz; 
  
    time_base_1kHz.num = 1; 
  
    time_base_1kHz.den = 1000; 
  
    packet.pts = av_rescale_q(timeStamp - baseTimeStamp_, time_base_1kHz, videoStream_->time_base); 

  where baseTimeStamp_ is the 1st timestamp of the stream.

  But if I try do similar calculation for audio, I don't get playable
  avi. If I always set to audio AV_NOPTS_VALUE, then avi has playable
  video, but no audio.

  So what are the correct values for audio time_base and pts's ?
  Do I set time_base and pts's for video correctly ?

• ffmpeg vs mencoder

  2 février 2013, par Jonah Braun

  I'm doing a bunch of video encoding for a variety of devices and platforms. I've bounced back and forth a few times between mencoder and ffmpeg. Which do you recommend and why ?

  Side question : From googling it seems that mencoder uses ffmpeg. Does it do this all the time or only when it deems necessary ?