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• open h.264 encoded stream and write the encoded AVPackets into mp4-file

  29 novembre 2013, par Olgen2013

  I want to read/open a h264 encoded video-file (.mp4) or live stream (rtp, tcp) and save this video or a part of this video into a h264 encoded mp4-file. I don't want to decode the input stream. So I want to read the AVPackets from the input stream and save them into a new container (output file (mp4)).

  So far I am able to read a video-file or live stream. For some test cases I implemented a method which decodes the input stream and stores each frame as image. This works fine, too.

  For the output part, which should write the input AVPackers into a mp4-file, I followed this example : http://libav.org/doxygen/release/0.8/libavformat_2output-example_8c-example.html.
  I adjusted the example for my case, without the encoding part of raw data.

  And I think there is my problem : while creating the AVCodecContex, which is also required to create the encoding parameters in the header of the output file.

  But my main problem is that I don't know which parameters of AVCodecContex are required for h264/mp4 and which values I need for each parameter. I tried to use the AVCodecContex from the input file/stream but partial there occur errors for some parameters. And like I said I don't know which parameters are really necessary for h264/mp4.

  I work with these versions :

  • libavutil 51. 22. 1 / 51. 22. 1
  • libavcodec 53. 35. 0 / 53. 35. 0
  • libavformat 53. 21. 1 / 53. 21. 1
  • libavdevice 53. 2. 0 / 53. 2. 0
  • libavfilter 2. 15. 0 / 2. 15. 0
  • libswscale 2. 1. 0 / 2. 1. 0
  • libpostproc 52. 0. 0 / 52. 0. 0

  What do you think ? Is my approach completely wrong or what could be the issue ?

  If you need further information just send me a message !

  Thanks for your help !
  Olgen

• Using FFMPEG and Open CV and encoding webcam stream to h264 in VC 2010

  22 novembre 2013, par Osaid

  I am trying to capture video stream and at the same time willing to encode it to h264 and save it to a file. I am using OpenCV to capture stream but am having problem converting them to h264 via FFMPEG. OS is WINDOWS XP and VC 2010 is the environment.

  I referred the encoding_decoding (refer video encoding section) provided by the FFMPEG. FFMPEG uses AVFrame i.e.

  AVFrame *frame;

  structure in which there is image data at frame->data but in OpenCV I am capturing frames in

  Mat WebCamFrame;
  
  cap >> WebCamFrame;   //Captures frame from webcam and puts it to WebCamFrame

  For encoding I have to get this captured WebCamFrame to frame->data then encode it using the

  avcodec_encode_video2(c, &pkt, frame, &got_output);

  in the encoding_decoding example a dummy image is created as

  /* prepare a dummy image */
  
  /* Y */
  
  for(y=0;yheight;y++) 
  
  {
  
      for(x=0;xwidth;x++)
  
      {
  
          frame->data[0][y * frame->linesize[0] + x] = x + y + i * 3;
  
      }
  
  }
  
  
  
  /* Cb and Cr */
  
  for(y=0;yheight/2;y++)
  
  {
  
      for(x=0;xwidth/2;x++) 
  
      {
  
          frame->data[1][y * frame->linesize[1] + x] = 128 + y + i * 2;
  
          frame->data[2][y * frame->linesize[2] + x] = 64 + x + i * 5;
  
      }
  
  }

  I do not want to use this dummy image rather the frame captured from webcam to encode it to h264. One more thing, the data type of WebCamFrame is MAT and that of frame is AVFrame. I would really appreciate a hint to proceed further. In a nutshell I want to process Mat frames (webCam video Stream) of OpenCV in FFMPEG avcodec_encode_video2() and write the video to a file.

• can't open video files with opencv in windows

  13 novembre 2018, par Barracuda

  I’m trying to open a video file in my program written in C++ using Visual Studio. I’ve tried adding the path to the environment using the answers to this question. But it still doesn’t work. What else do I have to do ?

  I’ve installed the opencv using this link. I have also downloaded the static ffmpeg using this link.