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• samplerate conversion function fails to produce an audible sound but only small pieces of audio

  2 juillet 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,22050,22050); // I think the result is 1/2 of audio speed
  
      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 0,5s:x=1:44100 x=22050 sample 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;
  
  //(LENGTH_MS*RATE*16*CHANNELS)/8000
  
  
  
      void resample(char in_buffer[],int out_rate,int nsamples,char out_buffer[])
  
      {
  
          //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;
  
          //*out_buffer = malloc(sizeof(in_buffer));
  
          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 sizeof(out_buffer)/2
  
              0);//is_last
  
          assert( samples_output > 0 && "Error calling av_resample()!" );
  
          av_resample_close( audio_cntx );    
  
      }

  When I run this code, the application part, the problem is that I hear the sound jerky, why ?
  The size of the array I think is right, I calculated considering that in the second half should be 22050 samples from store.

• AviSynth script with subtitles errors

  29 avril 2017, par Corpuscular

  Win7

  FFmpeg version : 20170223-dcd3418 win32 shared

  AVISynth version : 2.6

  Calling ffmpeg in a Visual Studio 2015 C# Forms Application and using process.StartInfo.Arguments to pass arguments and read an avs script. Works fine.

  The avs script :

  LoadPlugin("C:\Program Files (x86)\AviSynth 2.5\plugins\VSFilter.dll")
  
  
  
  a=ImageSource("01.png").trim(1,24)
  
  b=ImageSource("02.png").trim(1,36)
  
  c=ImageSource("03.png").trim(1,40)
  
  d=ImageSource("04.png").trim(1,72)
  
  e=ImageSource("05.png").trim(1,36)
  
  f=ImageSource("06.png").trim(1,40)
  
  video =  a + b + c + d + e + f
  
  
  
  return video

  I’d like to add subtitles using the avs script but it is not working. Adding the subtitle argument immediately before the "return video" argument results in :

  subtitle("day 111", align=2, first_frame=0, halo_color=$00FF00FF, text_color=$0000FF00, size=36, last_frame=100)

  Result error : [avisynth @ 003cdf20] Script error : Invalid arguments to function "subtitle"

  Using video.subtitle results in :

  video.subtitle("day 111", align=2, first_frame=0, halo_color=$00FF00FF, text_color=$0000FF00, size=36, last_frame=100)

  No error, script completes but no subtitle on output video.

  Using subtitle(clip) results in :

  subtitle(video, "day 111", align=2, first_frame=0, halo_color=$00FF00FF, text_color=$0000FF00, size=36, last_frame=100)

  The script exits abnormally but there is no error message.

  Any guidance would be greatly appreciated. Please let me know if I can clarify anything.

• Audio extraction in xamarin from mp4 file [duplicate]

  17 mars 2020, par rom_totach

  I need to convert an mp4 (or any other video format) to mp3 or wav file. I am using C# Xamarin.Forms. Any library I used either doesn’t work for me, or isn’t compatible with android. I have tried using Xamarin.Android.FFMpeg and Xobe.FFMpeg. I repost this because it was marked as duplicate and I clearly stated that that solution isn’t working for me. This is the post that was flagged as duplicate : How can I extract the audio out of a video file ? (android) . Please, I tried it but it just gives me the "Downloading Video Converter" dialog with a progress bar when I try to run the code in the solution, Also, it doesn’t even extract the audio so after the user waits such a long time, it turned out as a waste of time. Thanks in advance ! :)

  EDIT 1 :

  This is the code I am using :

  private async Task<string> ExtractAudioAsync(string path, Action<string> logger = null,
  
          Action onProgress = null)
  
      {
  
          List<string> cmd = new List<string>();
  
          cmd.Add("-i");
  
          cmd.Add(path + ".mp4");
  
          cmd.Add("-vn");
  
          cmd.Add("-acodec");
  
          cmd.Add("copy");
  
          cmd.Add(path + ".mp3");
  
          string cmdParams = string.Join(' ', cmd);
  
          await FFMpeg.Xamarin.FFMpegLibrary.Run(Context, cmdParams);
  
  
  
          return path + ".mp3";
  
      }
  
  </string></string></string></string>

  There are no exceptions thrown. When the Run method is called it just shows on the application the following dialog :

  

  After that, it just closes the dialog and goes to the return line without even extracting the audio out of the video. Even if I run this code again it does the same thing, downloading it again.

  EDIT 2 :

  I tried adding the -report option but it just did the same thing and did not save any log file. Am I doing something wrong ?