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• Mix voiceover and background music with delay and volume

  6 août 2019, par oldman

  I don’t master ffmpeg but I really need to mix a voiceover with a background song.

  The voiceover must start 5 seconds after the song, and must end 5 seconds before the song ends.

  The music volume must be loud for the first 5 seconds and the last 5 seconds, but during the voiceover it should remain low.

  Searching the internet, the closest I could come to my goal was this :

  ffmpeg -i music.mp3 -i voiceover.mp3 -filter_complex "[0]asplit[a][b]; [a]atrim=duration=5,volume='1-max(0.25*(t-13),0)':eval=frame[pre]; [b]atrim=start=5,asetpts=PTS-STARTPTS[song]; [song][1]amix=inputs=2:duration=shortest:dropout_transition=0[post]; [pre][post]concat=n=2:v=0:a=1[mixed]" -map " "[mixed]" output.mp3

  Could someone help me complete this script ?

• How to silent the MP3 decoding process

  3 août 2019, par Golu

  I am learning ffmpeg and I made a MP3 decoder but when I am executing it , some kind of information is printing on my terminal but I don’t want it. So how to silent it ?

  Here is code (full code)

  /* FFmpeg Usage Example
  
   * Date : 28 July 2019
  
   */
  
  #include 
  
  #include <libavformat></libavformat>avformat.h>
  
  #include <libavcodec></libavcodec>avcodec.h>
  
  #include <libavutil></libavutil>avutil.h>
  
  #include 
  
  
  
  int decode_packet(AVCodecContext*, AVPacket*, AVFrame*);
  
  
  
  int main(void) {
  
          AVFormatContext *pFormatContext = avformat_alloc_context();
  
          AVCodecParameters *pCodecParameters = NULL;
  
          if(avformat_open_input(&amp;pFormatContext,"song.mp3",NULL,NULL)!=0) {
  
                  fprintf(stderr,"Could not open file\n");
  
                  return -1;
  
          }
  
          if(avformat_find_stream_info(pFormatContext,NULL)&lt;0) {
  
                  fprintf(stderr,"Could not find stream\n");
  
                  return -1;
  
          }
  
  
  
          size_t stream_index = 0;
  
          for(;stream_indexnb_streams;stream_index++) {
  
                  if(pFormatContext->streams[stream_index]->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
  
                          pCodecParameters = pFormatContext->streams[stream_index]->codecpar;
  
                  }
  
                          break;
  
          }
  
  
  
          if(stream_index == -1) {
  
                  fprintf(stderr,"could not retrive stream info from file\n");
  
                  return -1;
  
          }
  
          AVStream *stream = pFormatContext->streams[stream_index];
  
          pCodecParameters = stream->codecpar;
  
          AVCodec *cdc = avcodec_find_decoder(pCodecParameters->codec_id);
  
          AVCodecContext *cdc_ctx = avcodec_alloc_context3(cdc);
  
          assert(pCodecParameters);
  
  
  
          if(avcodec_parameters_to_context(cdc_ctx,pCodecParameters) &lt; 0) {
  
                  fprintf(stderr,"Can't copy params to codec context\n");
  
                  return -1;
  
          }
  
  
  
          if(avcodec_open2(cdc_ctx,cdc,NULL) &lt; 0) {
  
                  fprintf(stderr,"Failed to open decoder for stream\n");
  
                  return -1;
  
          }
  
  
  
          AVFrame *frame = av_frame_alloc();
  
          if(!frame) {
  
                  fprintf(stderr,"could not allocate memory for frame\n");
  
                  return -1;
  
          }
  
  
  
          AVPacket *packet = av_packet_alloc();
  
  //      av_init_packet(&amp;packet);
  
          if(!packet) {
  
                  fprintf(stderr,"could not allocate memory for packet");
  
                  return -1;
  
          }
  
  
  
          packet->data=NULL;
  
          packet->size=0;
  
          // lets read the packets
  
          while(av_read_frame(pFormatContext,packet) >= 0) {
  
                  if(packet->stream_index==stream_index) {
  
                          int response = 0 ;
  
              response = decode_packet(cdc_ctx,packet,frame);
  
  
  
                          if(response &lt; 0)
  
                                  continue;
  
                  }
  
          av_packet_unref(packet);
  
          }
  
  
  
          return 0;
  
  }
  
  
  
  int decode_packet(AVCodecContext *cdc_ctx , AVPacket *pkt, AVFrame *frm) {
  
      int response = avcodec_send_packet(cdc_ctx,pkt);
  
      if(response &lt; 0)
  
          return response;
  
      while(response >= 0) {
  
          response = avcodec_receive_frame(cdc_ctx,frm);
  
          if(response == AVERROR(EAGAIN) || response == AVERROR_EOF)
  
              return -1;
  
          else if(response &lt; 0)
  
              return response;
  
      }
  
      return 0;
  
  }

  Expected behaviour : nothing should be printed on screen

  Actual behaviour : some kind of logs are printing automatically

  Here is output logs ( some of them )

  [mp3float @ 0x75172e7400] overread, skip -6 enddists: -5 -5         
  
  [mp3float @ 0x75172e7400] overread, skip -7 enddists: -6 -6
  
  [mp3float @ 0x75172e7400] overread, skip -6 enddists: -5 -5
  
  [mp3float @ 0x75172e7400] overread, skip -6 enddists: -4 -4

• How to pass a youtube video's audio url as ffmpeg source

  8 janvier 2020, par CrystallVR

  Im trying to get my discord bot to play the audio from any youtube videos using the video’s url from youtube-dl (the audio url) as the ffmpeg path/source. I got it to work kind of but, while testing, the ffmpeg throws an error in the middle of the audio and the process ends. Here is the error :
  https://i.imgur.com/uCy8SfK.png

  I’ve tried to play the same exact song by downloading it and using the file’s path as ffmpeg source path and it worked fine.

  Here is how i start the ffmpeg process :

              return Process.Start(new ProcessStartInfo
  
              {
  
                  FileName = "ffmpeg.exe",
  
                  Arguments = $"-xerror -i \"{path}\" -ac 2 -f s16le -ar 48000 pipe:1",
  
                  UseShellExecute = false,
  
                  RedirectStandardOutput = true
  
              });

  path is the audio url from youtube-dl process. (can also see the url in the error screenshot)

  And here is how i get the link from youtube-dl :

  Process youtubedl;
  
  
  
  
  
                  ProcessStartInfo youtubedlGetTitle = new ProcessStartInfo()
  
                  {
  
                      FileName = "youtube-dl",
  
                      Arguments = $"--get-title --get-duration --get-url {url}",
  
                      CreateNoWindow = true,
  
                      RedirectStandardOutput = true,
  
                      UseShellExecute = false
  
                  };
  
                  youtubedl = Process.Start(youtubedlGetTitle);
  
                  youtubedl.WaitForExit();

  url is a normal youtube video link.

  I just started working with ffmpeg and youtube-dl so there probably are some stupid rookie mistakes that i’m not aware of. I would appreciate any guidance and/or explanation of what I did wrong.