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• How to make audio sound better ? (C + FFMpeg audio generation example)

  21 février 2017, par Rella

  So I found this great C FFMpeg official example which I simplified :

  #include 
  
  #include 
  
  #include 
  
  
  
  #ifdef HAVE_AV_CONFIG_H
  
  #undef HAVE_AV_CONFIG_H
  
  #endif
  
  
  
  #include "libavcodec/avcodec.h"
  
  #include "libavutil/mathematics.h"
  
  
  
  #define INBUF_SIZE 4096
  
  #define AUDIO_INBUF_SIZE 20480
  
  #define AUDIO_REFILL_THRESH 4096
  
  
  
  /*
  
   * Audio encoding example
  
   */
  
  static void audio_encode_example(const char *filename)
  
  {
  
      AVCodec *codec;
  
      AVCodecContext *c= NULL;
  
      int frame_size, i, j, out_size, outbuf_size;
  
      FILE *f;
  
      short *samples;
  
      float t, tincr;
  
      uint8_t *outbuf;
  
  
  
      printf("Audio encoding\n");
  
  
  
      /* find the MP2 encoder */
  
      codec = avcodec_find_encoder(CODEC_ID_MP2);
  
      if (!codec) {
  
          fprintf(stderr, "codec not found\n");
  
          exit(1);
  
      }
  
  
  
      c= avcodec_alloc_context();
  
  
  
      /* put sample parameters */
  
      c->bit_rate = 64000;
  
      c->sample_rate = 44100;
  
      c->channels = 2;
  
  
  
      /* open it */
  
      if (avcodec_open(c, codec) < 0) {
  
          fprintf(stderr, "could not open codec\n");
  
          exit(1);
  
      }
  
  
  
      /* the codec gives us the frame size, in samples */
  
      frame_size = c->frame_size;
  
      samples = malloc(frame_size * 2 * c->channels);
  
      outbuf_size = 10000;
  
      outbuf = malloc(outbuf_size);
  
  
  
      f = fopen(filename, "wb");
  
      if (!f) {
  
          fprintf(stderr, "could not open %s\n", filename);
  
          exit(1);
  
      }
  
  
  
      /* encode a single tone sound */
  
      t = 0;
  
      tincr = 2 * M_PI * 440.0 / c->sample_rate;
  
      for(i=0;i<200;i++) {
  
          for(j=0;j* encode the samples */
  
          out_size = avcodec_encode_audio(c, outbuf, outbuf_size, samples);
  
          fwrite(outbuf, 1, out_size, f);
  
      }
  
      fclose(f);
  
      free(outbuf);
  
      free(samples);
  
  
  
      avcodec_close(c);
  
      av_free(c);
  
  }
  
  
  
  int main(int argc, char **argv)
  
  {
  
  
  
      /* must be called before using avcodec lib */
  
      avcodec_init();
  
  
  
      /* register all the codecs */
  
      avcodec_register_all();
  
  
  
      audio_encode_example("test.mp2");
  
  
  
      return 0;
  
  }

  How should it sound like ? May be I don’t get something but it sounds awful =( how to make audio generation sound better/ more interesting/ melodical in a wary shourt way (no special functions just how to change this code to make it sound better) ?

• Discord Bot No Sound Using ffmpeg - C#

  20 mars 2017, par J.Clarke

  I cant seem to get any audio with my discord bot using ffmpeg in c#.

  Here is the relevant code, am i missing something ?

          commands.CreateCommand("play").Do(async (e) =>
  
          {
  
              await e.Channel.SendMessage("Playing");
  
              var server = e.Server;
  
              var voiceChannel = client.FindServers(server.Name).FirstOrDefault().VoiceChannels.FirstOrDefault();
  
              var _vClient = await client.GetService<audioservice>()
  
                  .Join(voiceChannel);
  
  
  
              var pathOrUrl = "a.mp3";
  
  
  
              var process = Process.Start(new ProcessStartInfo
  
  
  
                  FileName = "ffmpeg",
  
                  Arguments = $"-i {pathOrUrl} " +
  
                              "-f s16le -ar 48000 -ac 1 pipe:1",
  
                  UseShellExecute = false,
  
                  RedirectStandardOutput = true
  
              });
  
              Thread.Sleep(2000);
  
  
  
              int blockSize = 3840;
  
              byte[] buffer = new byte[blockSize];
  
              int byteCount;
  
  
  
              while (true)
  
              {
  
                  byteCount = process.StandardOutput.BaseStream
  
                          .Read(buffer, 0, blockSize);
  
  
  
                  if (byteCount == 0) {
  
                      Console.WriteLine("Finished");
  
                      break;
  
                      }
  
  
  
                  _vClient.Send(buffer, 0, byteCount);
  
              }
  
              _vClient.Wait();
  
          });
  
  </audioservice>

  I used the only valid source i could find (There really isnt much documentation on this at all) here http://rtd.discord.foxbot.me/en/legacy/features/voice.html

  Thanks for the help !

• Get the actual duration of a sound file in C++ (libavformat)

  1er avril 2017, par user3734670

  I want to get the duration of a sound file in my C++ application. I want to support a lot of sound codecs, so I decided to use libavformat.

  I get the duration, but I get also a notification that the duration can be inaccurate. In another Stackoverflow question (How to get the real, actual duration of an MP3 file (VBR or CBR) server-side) it was mentioned that you can decode the file completely to get the actual duration. How can I this archive with libavformat ?

  My code to get the inaccurate duration :

  av_register_all();
  
  AVFormatContext* pFormatCtx = avformat_alloc_context();
  
  avformat_open_input(&pFormatCtx, audio_file, NULL, NULL);
  
  avformat_find_stream_info(pFormatCtx, 0);
  
  av_dump_format(pFormatCtx, 0, audio_file, 0);
  
  int64_t duration = pFormatCtx->duration;
  
  std::cout << ceil((double) duration / AV_TIME_BASE) << std::endl;
  
  avformat_close_input(&pFormatCtx);
  
  avformat_free_context(pFormatCtx);