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• ffmpeg transpose corrupts video [on hold]

  15 décembre 2016, par Victor.dMdB

  I’m trying to set up a transcoding pipeline with ffmpeg C lib, but if I transpose it, the video is corrupted as shown below.

  If I don’t transpose, the video is fine, ie the rest of the pipeline is correctly set up.

  I’m not actually sure what is actually the issue, is it a problem with the pxiel format ? Why is the transpose corrupting the video stream ? Is there something wrong with my code (added below) ?

  

  The constructor (code was taken from here)

  MyFilter::MyFilter(const std::string filter_desc, AVCodecContext *data_ctx){
  
    avfilter_register_all();
  
    buffersrc_ctx = NULL;
  
    buffersink_ctx = NULL;
  
  
  
      filter_graph = avfilter_graph_alloc();
  
  
  
    AVFilter *buffersink = avfilter_get_by_name("buffersink");
  
    if (!buffersink) {
  
      throw error("filtering sink element not found\n");
  
    }
  
  
  
    if (avfilter_graph_create_filter(&buffersink_ctx, buffersink, "out", NULL, NULL, filter_graph) < 0) {
  
      throw error("Cannot create buffer sink\n");
  
    }
  
  
  
  
  
  filterInputs  = avfilter_inout_alloc();
  
    filterInputs->name       = av_strdup("out");
  
    filterInputs->filter_ctx = buffersink_ctx;
  
    filterInputs->pad_idx    = 0;
  
    filterInputs->next       = NULL;
  
  
  
      AVFilter *buffersrc  = avfilter_get_by_name("buffer");
  
      if (!buffersrc) {
  
          throw error("filtering source element not found\n");
  
      }
  
  
  
      char args[512];
  
      snprintf(args, sizeof(args), "video_size=%dx%d:pix_fmt=%d:time_base=%d/%d:pixel_aspect=%d/%d",
  
                      data_ctx->width, data_ctx->height, data_ctx->pix_fmt,
  
                      data_ctx->time_base.num, data_ctx->time_base.den,
  
                      data_ctx->sample_aspect_ratio.num, data_ctx->sample_aspect_ratio.den);
  
  
  
      log(Info, "Setting filter input with %s", args);
  
  
  
  
  
      if (avfilter_graph_create_filter(&buffersrc_ctx, buffersrc, "in", args, NULL, filter_graph) < 0) {
  
           throw error("Cannot create buffer source\n");
  
      }
  
  
  
      filterOutputs = avfilter_inout_alloc();
  
      filterOutputs->name       = av_strdup("in");
  
      filterOutputs->filter_ctx = buffersrc_ctx;
  
      filterOutputs->pad_idx    = 0;
  
      filterOutputs->next       = NULL;
  
  
  
      if ((avfilter_graph_parse(filter_graph, filter_desc.c_str(), filterInputs, filterOutputs, NULL)) < 0)
  
              log(Warning,"Could not parse input filters");
  
  
  
      if ((avfilter_graph_config(filter_graph, NULL)) < 0)
  
          log(Warning,"Could not configure filter graph");
  
  
  
  }

  And the process

  AVFrame * MyFilter::process(AVFrame *inFrame){
  
  
  
      if (av_buffersrc_add_frame_flags(buffersrc_ctx, inFrame->get(), AV_BUFFERSRC_FLAG_PUSH | AV_BUFFERSRC_FLAG_KEEP_REF ) < 0) {
  
           throw error("Error while feeding the filtergraph\n");
  
       }
  
  
  
      int i = 0;
  
      AVFrame* outFrame =  av_frame_alloc();
  
      if( av_buffersink_get_frame(buffersink_ctx, outFrame) < 0 ){
  
       throw error("Couldnt find a frame\n");
  
      }
  
    return outFrame;
  
  }

  And the filter I’m using is :

   std::string filter_desc = "transpose=cclock"

  As an extra note, it seems like the top bar(visible in the screen capture above) is actually composed of properly rotated pixels, and this works for the whole video. It just degrades for the remaining 99% of pixels.

  EDIT :

  Using this works std::string filter_desc = "rotate=1.58", but then the resolution is not properly shifted.

• Problems with ffmpeg build in Xcode

  16 décembre 2016, par jon

  Hi I have a problem with getting ffmpeg libraries to build in my Xcode project. It is in C++ . I have installed it using homebrew and have checked that all the correct libraries have installed via terminal. I have tried with and without extern C as I know it is a c library.

  #include <iostream>
  
  #include <opencv2></opencv2>opencv.hpp>
  
  
  
  #include <libavformat>
  
  
  
  //extern "C" {
  
  //    #include <libavformat>
  
  //}
  
  </libavformat></libavformat></iostream>

  The linker flags have been set by using (e.g. pkg-config —libs libavcodec) in terminal and these flags do not throw up an error when building. The header files are also found with no problems as the autocomplete flags them top while typing.

  Please see attached pictures for Xcode build settings. Really stuck pease help

  

• opencv2 can't load video on mac

  28 novembre 2016, par bogun

  I can’t use cv2.VideoCapture(’test.avi’) to load my local video.
  I had installed ffmpeg using brew install ffmpeg
  When i try to run the code cv2.VideoCapture(test.avi), the python process will crash, here is the error log :

  '2016-11-28 18:18:47.768 Python[20241:277423] *** Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[__NSArrayM objectAtIndex:]: index 0 beyond bounds for empty array

  *** First throw call stack :
  (
  0 CoreFoundation 0x00007fffa44b148b __exceptionPreprocess + 171
  1 libobjc.A.dylib 0x00007fffb8c13cad objc_exception_throw + 48
  2 CoreFoundation 0x00007fffa43cad8c -[__NSArrayM objectAtIndex :] + 204
  3 libopencv_highgui.2.4.dylib 0x0000000109be9270 _ZN13CvCaptureFileC2EPKc + 350
  4 libopencv_highgui.2.4.dylib 0x0000000109be7ce2 _Z32cvCreateFileCapture_AVFoundationPKc + 34
  5 libopencv_highgui.2.4.dylib 0x0000000109bdb7de cvCreateFileCapture + 14
  6 libopencv_highgui.2.4.dylib 0x0000000109bdba8e _ZN2cv12VideoCapture4openERKNSt3__112basic_stringIcNS1_11char_traitsIcEENS1_9allocatorIcEEEE + 64
  7 libopencv_highgui.2.4.dylib 0x0000000109bdb8ee _ZN2cv12VideoCaptureC2ERKNSt3__112basic_stringIcNS1_11char_traitsIcEENS1_9allocatorIcEEEE + 42
  8 cv2.so 0x0000000109387bce _ZL34pyopencv_VideoCapture_VideoCaptureP7_objectS0_S0_ + 275
  9 Python 0x0000000109052534 PyEval_EvalFrameEx + 14624
  10 Python 0x000000010904ea1e PyEval_EvalCodeEx + 1617
  11 Python 0x000000010904e3c7 PyEval_EvalCode + 48
  12 Python 0x000000010906e63d PyParser_ASTFromFile + 297
  13 Python 0x000000010906e46b PyRun_InteractiveOneFlags + 377
  14 Python 0x000000010906df5f PyRun_InteractiveLoopFlags + 192
  15 Python 0x000000010906de09 PyRun_AnyFileExFlags + 60
  16 Python 0x000000010907fbca Py_Main + 3094
  17 libdyld.dylib 0x00007fffb94f2255 start + 1
  18 ??? 0x0000000000000001 0x0 + 1
  )
  libc++abi.dylib : terminating with uncaught exception of type NSException
  Abort trap : 6

  I guess the video’s codec could be wrong, but i don’t know how to fix it.