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• Build ffmpeg binary for android

  26 juillet 2014, par Abdul Qadir

  I’ve gone through various tutorials on the Internet. I need to execute simple ffmpeg commands in my android application. I found the guardianproject’s android library perfect for it but I needed to enable libmp3lame in the configuration file and re-build the binary so i can work with mp3 files. But I couldn’t re-built it successfully. I got following errors :

  config.mk:25: builds/unix/unix-def.mk: No such file or directory
  
  config.mk:26: builds/unix/unix-cc.mk: No such file or directory
  
  make: *** No rule to make target builds/unix/unix-cc.mk.  Stop.
  
  Makefile:2: config.mak: No such file or directory
  
  Makefile:47: /common.mak: No such file or directory
  
  Makefile:88: /libavutil/Makefile: No such file or directory
  
  Makefile:88: /library.mak: No such file or directory
  
  Makefile:168: /doc/Makefile: No such file or directory
  
  Makefile:169: /tests/Makefile: No such file or directory
  
  make: *** No rule to make target /tests/Makefile.  Stop.
  
  Makefile:2: config.mak: No such file or directory
  
  Makefile:47: /common.mak: No such file or directory
  
  Makefile:88: /libavutil/Makefile: No such file or directory
  
  Makefile:88: /library.mak: No such file or directory
  
  Makefile:168: /doc/Makefile: No such file or directory
  
  Makefile:169: /tests/Makefile: No such file or directory
  
  make: *** No rule to make target /tests/Makefile.  Stop.
  
  ./configure_sox.sh: line 12: autoreconf: command not found
  
  ./configure_sox.sh: line 15: ./configure: No such file or directory
  
  make: *** No targets specified and no makefile found.  Stop.
  
  make: *** No rule to make target 'install-strip'.  Stop.

  I also tried this tutorial to build a binary but failed. The errors I encounter are following :

  /home/aq/Downloads/android-ndk-r8e/toolchains/arm-linux-androideabi-4.7/prebuilt/linux-x86_64/bin/arm-linux-androideabi-ld: ,noexecstack: unknown -z option
  
  /home/aq/Downloads/android-ndk-r8e/toolchains/arm-linux-androideabi-4.7/prebuilt/linux-x86_64/bin/arm-linux-androideabi-ld: use the --help option for usage information

  I was successful in building various .so files through this tutorial though :

  But i don’t know how to use those .so files. I guess these are the libraries. Is there any way I can execute ffmpeg commands through these .so files ? Any help would be appreciated !!

• it's hang when using av_interleaved_write_frame

  19 avril 2018, par Eric Nguyen

  I use the ffmpeg to stream the encoded video.
  when it is streaming, it plug out the internet cable, it means connection to the serve is lost.
  the video is hangs, i can not handle after that. i see the reason that it is hang at av_interleaved_write_frame(), the function doesn’t return result or any error, it hangs forever at there.

  Anyone see that issue, and Can you help me to fix that bug.
  Thanks.

• 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 !