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• What's the most elegant way to get the language codes from an MKV file with multiple audio tracks ?

  30 janvier 2017, par WackGet

  I need a way to get the language codes from MKV files which have multiple audio tracks.

  ffmpeg produces output which I could then filter using regular expressions but it doesn’t seem very elegant :

  $ ffmpeg -i file.mkv 2>&1 | grep Audio
  
  Stream #0:1(eng): Audio: mp2, 48000 Hz, stereo, s16, 192 kb/s (default)
  
  Stream #0:2(nar): Audio: mp2, 48000 Hz, mono, s16, 64 kb/s (default)

  mediainfo has the ability to extract language information but in files with multiple tracks, it concatenates the codes into a single string :

  $ mediainfo file.mkv --inform="Audio;%Language%"  
  
  ennar

  Is there a tool or command which will return language codes for multiple tracks in a nicer way, or a tool which would let me specify a track number and return the language code for that track only ?

• Add several texts to ffmpeg slideshow video

  29 décembre 2016, par kostya572

  I have slideshow video created from images with :

  ffmpeg -r 60 -video_size 1280x720 \
  
  -loop 1 -t 5 -i ok/image-1.jpg \
  
  -loop 1 -t 2.5 -i ok/image-2.jpg \
  
  -loop 1 -t 2.5 -i ok/image-3.jpg \
  
  -loop 1 -t 2.5 -i ok/image-4.jpg \
  
  -loop 1 -t 2.5 -i ok/image-5.jpg \
  
  -filter_complex \
  
  "[1:v][0:v]blend=all_expr='A*(if(gte(T,0.5),1,T/0.5))+B*(1-(if(gte(T,0.5),1,T/0.5)))'[b1v]; \
  
   [2:v][1:v]blend=all_expr='A*(if(gte(T,0.5),1,T/0.5))+B*(1-(if(gte(T,0.5),1,T/0.5)))'[b2v]; \
  
   [3:v][2:v]blend=all_expr='A*(if(gte(T,0.5),1,T/0.5))+B*(1-(if(gte(T,0.5),1,T/0.5)))'[b3v]; \
  
   [4:v][3:v]blend=all_expr='A*(if(gte(T,0.5),1,T/0.5))+B*(1-(if(gte(T,0.5),1,T/0.5)))'[b4v]; \
  
  [0:v][b1v][1:v][b2v][2:v][b3v][3:v][b4v][4:v]concat=n=9:v=1:a=0,format=yuv420p[v];" -map "[v]" out.mp4

  I know that i can add text with drawtext=fontfile=OpenSans-Regular.ttf:text='Title of this Video':fontcolor=white:fontsize=24:x=(w-tw)/2:y=(h/PHI)+th; Also i know there is possibility to make text duration for example from first second to fifth second with drawtext=enable='between(t,1,5)'. How can i combine multiple texts with different durations with code provided below ?

• Coverting JPEG images or webcam stream to video using C language with ffmpeg wrapper or any othe way

  19 décembre 2016, par Chakri

  I’m writing a C program that access webcam using linux-v4l2 to record in a video file. I’m able to take jpeg pictures using v4l2 and libjpeg. Here is the part of code :

  int jpgfile; 
  
  if((jpgfile = open("/tmp/myimage.jpeg", O_WRONLY | O_CREAT, 0660)) < 0){
  
      perror("open");
  
      exit(1);
  
      }
  
  
  
  write(jpgfile, buffer, buf.length);
  
  close(jpgfile);

  I want to replace this peice of code to a ’equivalent video code’ or to convert that jpeg stream (or raw buffer stream) to a video file using libraries or through pipelining because writing to disk requires more cycles. I’ve come across ffmpeg wrappers like avcodec.h but they lack proper documentation.

  Please give me advice to convert to video file.