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• FFmpeg.swr_convert : audio to raw 16 bit pcm, to be used with xna SoundEffect. Audio cuts out when i convert

  21 mars 2019, par Robert Russell

  I want to resample mkv(vp8/ogg) and also raw 4 bit adpcm to raw 16bit pcm byte[] to be loaded into SoundEffect from xna library. So I can play it out while I’m using other code to display the frames (the video side is working).
  I can read a 16 bit wav file and play it. But when I goto resample something it doesn’t play 100%. One file is 3 mins and 15 secs. I only get 13 sec and 739 ms before it quits playing. I have been learning to do this by finding code samples in c++ and correcting it to work in c# using ffmpeg.autogen.

  the below is my best attempt at resampling.

              int nb_samples = Frame->nb_samples;
  
                      int output_nb_samples = nb_samples;
  
                      int nb_channels = ffmpeg.av_get_channel_layout_nb_channels(ffmpeg.AV_CH_LAYOUT_STEREO);
  
                      int bytes_per_sample = ffmpeg.av_get_bytes_per_sample(AVSampleFormat.AV_SAMPLE_FMT_S16) * nb_channels;
  
                      int bufsize = ffmpeg.av_samples_get_buffer_size(null, nb_channels, nb_samples,
  
                                                               AVSampleFormat.AV_SAMPLE_FMT_S16, 1);
  
  
  
                      byte*[] b = Frame->data;
  
                      fixed (byte** input = b)
  
                      {
  
                          byte* output = null;
  
                          ffmpeg.av_samples_alloc(&output, null,
  
                              nb_channels,
  
                              nb_samples,
  
                              (AVSampleFormat)Frame->format, 0);//
  
  
  
                          // Buffer input
  
  
  
                          Ret = ffmpeg.swr_convert(Swr, &output, output_nb_samples / 2, input, nb_samples);
  
                          CheckRet();
  
                          WritetoMs(output, 0, Ret * bytes_per_sample);
  
                          output_nb_samples -= Ret;
  
  
  
                          // Drain buffer
  
                          while ((Ret = ffmpeg.swr_convert(Swr, &output, output_nb_samples, null, 0)) > 0)
  
                          {
  
                              CheckRet();
  
                              WritetoMs(output, 0, Ret * bytes_per_sample);
  
                              output_nb_samples -= Ret;
  
                          }
  
                      }

  I changed that all to this but it cuts off sooner.

    Channels = ffmpeg.av_get_channel_layout_nb_channels(OutFrame->channel_layout);
  
                      int nb_channels = ffmpeg.av_get_channel_layout_nb_channels(ffmpeg.AV_CH_LAYOUT_STEREO);
  
                      int bytes_per_sample = ffmpeg.av_get_bytes_per_sample(AVSampleFormat.AV_SAMPLE_FMT_S16) * nb_channels;
  
  
  
                      if((Ret = ffmpeg.swr_convert_frame(Swr, OutFrame, Frame))>=0)
  
                          WritetoMs(*OutFrame->extended_data, 0, OutFrame->nb_samples * bytes_per_sample);
  
                      CheckRet();

  Both code use a function to set Swr it runs one time after the first frame is decoded.

          private void PrepareResampler()
  
      {
  
          ffmpeg.av_frame_copy_props(OutFrame, Frame);
  
          OutFrame->channel_layout = ffmpeg.AV_CH_LAYOUT_STEREO;
  
          OutFrame->format = (int)AVSampleFormat.AV_SAMPLE_FMT_S16;
  
          OutFrame->sample_rate = Frame->sample_rate;
  
          OutFrame->channels = 2;
  
          Swr = ffmpeg.swr_alloc();
  
          if (Swr == null)
  
              throw new Exception("SWR = Null");
  
          Ret = ffmpeg.swr_config_frame(Swr, OutFrame, Frame);
  
          CheckRet();
  
          Ret = ffmpeg.swr_init(Swr);
  
          CheckRet();
  
          Ret = ffmpeg.swr_is_initialized(Swr);
  
          CheckRet();
  
      }

  This is where I take the output and put it in the sound effect

  private void ReadAll()
  
      {
  
  
  
          using (Ms = new MemoryStream())
  
          {
  
              while (true)
  
              {
  
                  Ret = ffmpeg.av_read_frame(Format, Packet);
  
                  if (Ret == ffmpeg.AVERROR_EOF)
  
                      break;
  
                  CheckRet();
  
                  Decode();
  
              }
  
              if (Ms.Length > 0)
  
              {
  
                  se = new SoundEffect(Ms.ToArray(), 0, (int)Ms.Length, OutFrame->sample_rate, (AudioChannels)Channels, 0, 0);
  
                  //se.Duration; Stream->duration;
  
  
  
  
  
                  see = se.CreateInstance();
  
                  see.Play();
  
              } 
  
          }
  
      }

• Disable image resizing on the Basic Plus and AngularJS demo for Android and Opera.

  12 juin 2013, par blueimp

  Disable image resizing on the Basic Plus and AngularJS demo for Android and Opera.

• mpegaudiodec : cosmetics : basic pretty-printing

  27 septembre 2011, par Justin Ruggles

  mpegaudiodec : cosmetics : basic pretty-printing