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• Can somebody say why that doesn't work

  6 août 2018, par atif sesu

  I want to convert webm to mp4.

  private String ffmpegApp;
  
  
  
  public FLVConverter(String ffmpegApp) {
  
      this.ffmpegApp = ffmpegApp;
  
  }
  
  
  
  public void convert(String filenameIn, String filenameOut, int width, int height) throws IOException, InterruptedException {
  
      convert(filenameIn, filenameOut, width, height, -1);
  
  }
  
  
  
  public int convert(String filenameIn, String filenameOut, int width, int height, int quality)
  
          throws IOException, InterruptedException {
  
      ProcessBuilder processBuilder;
  
      if (quality > -1) {
  
          processBuilder = new ProcessBuilder(ffmpegApp, "-i", filenameIn, "-ar", "44100",
  
                  "-s", width + "*" + height, "-qscale", quality + "", filenameOut);
  
      } else {
  
          processBuilder = new ProcessBuilder(ffmpegApp, "-i", filenameIn, "-ar", "44100",
  
                  "-s", width + "*" + height, filenameOut);
  
      }
  
  
  
      Process process = processBuilder.start();
  
  
  
      InputStream stderr = process.getErrorStream();
  
      InputStreamReader isr = new InputStreamReader(stderr);
  
      BufferedReader br = new BufferedReader(isr);
  
      String line;
  
      while ((line = br.readLine()) != null) ;
  
  
  
      {
  
      }
  
  
  
      return process.waitFor();
  
  }
  
  
  
  public static void main(String[] args) throws Exception {
  
      FLVConverter FLVConverter = new FLVConverter("C:\\Users\\Casper\\Desktop\\ffmpeg\\bin\\ffmpeg.exe");
  
      FLVConverter.convert("C:\\Users\\Casper\\Desktop\\videoplayback.webm",
  
              "C:\\Users\\Casper\\Desktop\\a.mp4", 300, 200, 5);
  
  }

• Mavericks OpenCV 2.4.9 videoWriter doesn't work

  29 septembre 2014, par Maggick

  I’m having issues writing out video files using OpenCV on Mac.

  I’m running Mavericks and have OpenCV 2.4.9 and FFMPEG 2.4.1 installed, and the newest x264 from videolan.

  But when I run even the example code from opencv website I still am not able to produce a video. http://docs.opencv.org/doc/tutorials/highgui/video-write/video-write.html

  When I run the example code I get a blank video file.

  So my code doesn’t seem to be the problem. And I don’t get any errors so I am assuming the problem is with the codec not working. But I don’t understand what I am missing.

  Has anyone else had a similar problem ? Since I’m using a Mac I cannot use the -1 flag to pick a codec.

• How does FFMPEG copy work ?

  24 novembre 2017, par Tyler Brooks

  How can I implement the equivalent of this command :

  ffmpeg -i test.h264 -vcodec copy -hls_time 5 -hls_list_size 0 foo.m3u8

  My understanding is that you do something like this (pseudo code for clarity) :

  avformat_open_input(&ctx_in, "test.h264", NULL, NULL);
  
  avformat_find_stream_info(ctx_in, NULL);
  
  
  
  avformat_alloc_output_context2(&ctx_out, NULL, "hls", "foo.m3u8");
  
  strm_out = avformat_new_stream(ctx_out, NULL);
  
  strm_out->time_base = (AVRational){1000000, FRAMERATE};
  
  
  
  strm_out->codecpar->codec_id = AV_CODEC_ID_H264;
  
  strm_out->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
  
  strm_out->codecpar->width = width;
  
  strm_out->codecpar->height = height;
  
  strm_out->codecpar->bit_rate = bitrate;
  
  strm_out->codecpar->codec_tag = 0;
  
  
  
  avcodec_parameters_copy(ctx_out->streams[0]->codecpar,
  
    ctx_in->streams[0]->codecpar);
  
  
  
  avformat_write_header(ctx_out, NULL);
  
  
  
  while(1) {
  
    AVPacket pkt;
  
  
  
    ret = av_read_frame(ctx_in, &pkt);
  
    if (ret < 0)
  
      break;
  
  
  
    pkt.pos = -1;
  
    pkt.stream_index = 0;
  
    pkt.dts = AV_NOPTS_VALUE;
  
    pkt.pts = AV_NOPTS_VALUE;
  
    pkt.pts = SOME_DURATION;
  
  
  
    av_write_frame(ctx_out, &pkt);
  
    av_packet_unref(&pkt);
  
  }
  
  avformat_close_input(&ctx_in);
  
  av_write_trailer(ctx_out);
  
  avformat_free_context(ctx_out);

  I crash on the avformat_find_stream_info() call. I think this is the case because an H264 elemental stream is not really a container (which avformat wants).

  What is the proper way to implement the FFMPEG ’copy’ command of an elemental stream ?