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• FFmpeg for beginners

  14 août 2017, par Rick

  I use Linuxmint and was referred to FFmpeg. After searching the web for various tutorials and help, I tried to rip a DVD to .avi and just didn’t have the skills/knowledge of FFmpeg to make it a successful operation. What I need is a GOOD tutorial, step-by-step commands on how to rip a DVD. I’m able to get a good (I think) listing of the various command (pastebin.com/NQ5pbGr2) yet don’t know how to "write" them together to make a "proper" command. Yup, in need of some good help !!!
  THANX :
  Rick

• C++ ffmpeg extract audio to mp3 (demuxing)

  29 juin 2014, par Unknown

  I am trying to write a C++ program that allows me to extract the audio from a video file to an mp3 file. I searched the internet and stackoverflow, but couldn’t get it to work.

  The library I chose is ffmpeg and I have to do it in C/C++. This is what I have so far.

  // Step 1 - Register all formats and codecs
  
  avcodec_register_all();
  
  av_register_all();
  
  
  
  AVFormatContext* fmtCtx = avformat_alloc_context();
  
  
  
  // Step 2 - Open input file, and allocate format context
  
  if(avformat_open_input(&fmtCtx, filePath.toLocal8Bit().data(), NULL, NULL) < 0)
  
      qDebug() << "Error while opening " << filePath;
  
  
  
  // Step 3 - Retrieve stream information
  
  if(avformat_find_stream_info(fmtCtx, NULL) < 0)
  
      qDebug() << "Error while finding stream info";
  
  
  
  // Step 4 - Find the audiostream
  
  audioStreamIdx = -1;
  
  for(uint i=0; inb_streams; i++) {
  
      if(fmtCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_AUDIO) {
  
          audioStreamIdx = i;
  
          break;
  
      }
  
  }
  
  
  
  if(audioStreamIdx != -1) {
  
      // Step 5
  
      AVCodec *aCodec = avcodec_find_decoder(AV_CODEC_ID_MP3);
  
      AVCodecContext *audioDecCtx = avcodec_alloc_context3(aCodec);
  
  
  
      avcodec_open2(audioDecCtx, aCodec, NULL);
  
  
  
      // Step 6
  
      AVPacket pkt;
  
      AVFrame *frame = av_frame_alloc();
  
  
  
      av_init_packet(&pkt);
  
  
  
      pkt.data = NULL;
  
      pkt.size = 0;
  
  
  
      int got_packet = 0;
  
  
  
      while(av_read_frame(fmtCtx, &pkt) == 0) {
  
          int got_frame = 0;
  
  
  
          int ret = avcodec_decode_audio4(audioDecCtx, frame, &got_frame, &pkt);
  
  
  
          if(got_frame) {
  
              qDebug() << "got frame";
  
          }
  
      }
  
  
  
      av_free_packet(&pkt);
  
  }
  
  
  
  avformat_close_input(&fmtCtx);

  But the error I get when executing avcodec_decode_audio4() is "[mp3 @ 825fc30] Header missing".

  Thanks in advance !

  [EDIT]
  I found out that the audio of the video was not MP3 but AAC. So I changed Step 5 to the following lines of code

      // Step 5
  
      AVCodecContext *audioDecCtx = fmtCtx->streams[audioStreamIdx]->codec;
  
      AVCodec *aCodec = avcodec_find_decoder(audioDecCtx->codec_id);
  
  
  
      avcodec_open2(audioDecCtx, aCodec, NULL);

  Now it outputs "got frame" and the avcodec_decode_audio4() returns the number of bytes it decoded.

  Now I have to write the audio to a file, preferably to an MP3 file. I found out that I have to do it with the function avcodec_encode_audio2(). But some extra help on how to use it is more then welcome !

• FFMPEG integration for TVOS

  24 avril 2016, par gav

  I’m use to using MOBILEVLCKit or even TVVLCKit (but won’t compile ATM) so I have looked into raw FFMPEG though this FFMPEG build script for iOS & TVOS which compiled great but how do I go from a dir fill of lib*.a files to integrating them into a TVOS app and pulling a working player from the libs.
  If anyone could provide a step by step that would be so helpful.
  Thanks