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• Segmentation fault in samplerate conversion function

  17 juin 2014, par user3749290

  playmp3() using libmpg123

  if (isPaused==0 && mpg123_read(mh, buffer, buffer_size, &done) == MPG123_OK)
  
  {
  
      char * resBuffer=&buffer[0]; //22100=0,5s
  
      buffer = resample(resBuffer,22100,22100);
  
      if((ao_play(dev, (char*)buffer, done)==0)){
  
          return 1;
  
  }

  resample() Using avcodec from ffmpeg

  #define LENGTH_MS 500       // how many milliseconds of speech to store
  
  #define RATE 44100      // the sampling rate (input)
  
  #define FORMAT PA_SAMPLE_S16NE  // sample size: 8 or 16 bits
  
  #define CHANNELS 2      // 1 = mono 2 = stereo
  
  
  
  struct AVResampleContext* audio_cntx = 0;
  
  
  
  char * resample(char in_buffer[(LENGTH_MS*RATE*16*CHANNELS)/8000],int out_rate,int nsamples)
  
  {
  
      char out_buffer[ sizeof( in_buffer ) * 4];
  
      audio_cntx = av_resample_init( out_rate, //out rate
  
          RATE, //in rate
  
          16, //filter length
  
          10, //phase count
  
          0, //linear FIR filter
  
          1.0 ); //cutoff frequency
  
      assert( audio_cntx && "Failed to create resampling context!");
  
      int samples_consumed;
  
      int samples_output = av_resample( audio_cntx, //resample context
  
          (short*)out_buffer, //buffout
  
          (short*)in_buffer,  //buffin
  
          &samples_consumed,  //&consumed
  
          nsamples,       //nb_samples
  
          sizeof(out_buffer)/2,//lenout
  
          0);//is_last
  
      assert( samples_output > 0 && "Error calling av_resample()!" );
  
      av_resample_close( audio_cntx );
  
      //*resample = malloc(sizeof(out_buffer));
  
      return &out_buffer[0];  
  
  }

  When i run this code i get 3393 Segmentation fault (core dump created). Why ?

  For example, the use of pointers is correct ?
  and 22100 are the samples that are contained in 0.5 seconds of the song ?

• ffmpeg add subtitle from a variable and not a file

  7 mai 2017, par Sulli

  I would like to add a subtitle to a short video clip but my subtitle is in a variable and not in a file.

  Is there a way to do that ? Something like :

  ffmpeg -i input.mp4 -vf "subtitles='$title':force_style='Fontsize=24,PrimaryColour=&H0000ff&'" -c:a copy output.mp4

  (which is not working of course as ffmpeg asks for a file)

  I also tried to use drawtext instead but my subtitle needs to be wrapped.

• ffmpeg - Remove slow motion from MOV

  16 juillet 2020, par KalemKutu

  I recorded a short movie with an iPhone.
No idea how I did, but a part of the video is in slow motion.

  


  I want to play but also store the video on my computer MAC in "normal" speed,
if possible without losing quality & without encoding.

  


  I tried following parameters in ffmpeg, which works.
But I have the feeling the outcome quality has reduced "little-bit".

  


  ffmpeg -i input.MOV -r 30  output.MOV


  


  Is there a better way ?

  


  Thanks, Kalem