Recherche avancée

Sur d’autres sites (8386)

• pnacl-clang doesn't know where ffmpeg libraries are (but Eclipse does ?)

  10 août 2014, par lavsprat

  I’m trying to make my first "hello world"-like app using ffmpeg libraries. I already got NaCl SDK and downloaded & compiled the ffmpeg port.

  This is my code :

  main.c

  #include <libavformat></libavformat>avformat.h>
  
  
  
  int main()
  
  {
  
      av_register_all();
  
      return 0;
  
  }

  Building with $ (...)/pnacl-clang main.c -o main -lavformat in terminal.

  The output :

  main.c:2:10: fatal error: 'libavformat/avformat.h' file not found
  
  #include <libavformat></libavformat>avformat.h>
  
           ^

  Now, why am I not using -L(...)\lib and -I(...)\include in the build command ? Because it should work without it. In my workplace nacl-clang somehow knows where the libs are and compiles everything successfully. Why is that not working on my personal computer ? How can I permanently let pnacl-clang know where to look for them ?

• How to specify bit rate while using concatenating videos ?

  2 juillet 2018, par r.mirzojonov

  I’ve been trying to write ffmpeg command that would take 3 mp4 videos(intro, main, outro) and 1 image (logo) then it would resize intro and concatenate them while adding logo to main video.

  ffmpeg -i intro.mp4 -i main.mp4 -i outro.mp4 -i logo.png -filter_complex "[0:v]scale=1280:720,setsar=sar=1[scaled]; [1][3]overlay=5:5[main]; [scaled][0:a][main][1:a][2:v][2:a]concat=n=3:v=1:a=1 [v] [a]" -map "[v]" -map "[a]" -c:a aac output.mp4

  So far this works fine, but when I try to specify the bit rate of output file. Here it says that I need to use Two-pass method but I don’t know to correctly apply that method in my case, because the example shown there uses only 1 video while mine concatenates them.
  Should I even use two-pass method or is there any other way to specify bit rate ?

• Capture rtsp stream to MP4 file with wallclock timestamp preserve moov atom

  11 avril 2024, par Jax2171

  We are looking for the right ffmpeg options to capture the rtsp stream from an IP camera using the real time in epoch from the wall clock as a timestamps reference. Our current command is as follows :

  


  ffmpeg -use_wallclock_as_timestamps 1 -rtsp_transport tcp -i rtsp://admin:admin@192.168.5.21/h264/ch1/main/av_stream -c:v copy -c:a aac -copyts -f mp4 -y record.mp4


  


  The command works perfectly well except that, if for any reason the ffmpeg process were to stop abruptly, the output file "record.mp4" is unreadable with error :

  


  


  moov atom not found

  


  


  We simulated the abrupt termination with the pkill -9 ffmpeg command with the acquisition stream started.

  


  Adding the -movflags +faststart option didn't work. The video file cannot be played.

  


  Adding the -movflags frag_keyframe+empty_moov option keeps the video file executable but resets the timestamp to start from 0, thus not solving our goal.

  


  PS : The matroska container seems to be the solution, however we encountered strange frequent lag and duplicate frames with the same timestamp. For this reason it was not taken into consideration.

  


  Thanks in advance.