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• How to edit a frame's content using ffmpeg and opencv ?

  15 août 2017, par md612

  I am going to edit the content of one frame from a mp4 file using OpenCV and ffmpeg 3.3. However, I encountered some problems such as the width and the height of video are zero, some functions are deprecated. I have changed the old function to updated function, but still cannot extract a correct frame. Please help.

  Can anyone show an example of extracting a frame from a mp4 file using ffmpeg 3.3 ?

  #include "stdafx.h"
  
  #include <iostream>
  
  #include <vector>
  
  #include <opencv2></opencv2>core/core.hpp>
  
  #include <opencv2></opencv2>highgui/highgui.hpp>
  
  #include <opencv2></opencv2>imgproc/imgproc.hpp>
  
  // FFmpeg
  
  extern "C" {
  
  #include <libavformat></libavformat>avformat.h>
  
  #include <libavcodec></libavcodec>avcodec.h>
  
  #include <libavutil></libavutil>avutil.h>
  
  #include <libavutil></libavutil>pixdesc.h>
  
  #include <libswscale></libswscale>swscale.h>
  
  #include <libavutil></libavutil>imgutils.h>
  
  
  
  }
  
  #define CODEC_TYPE_VIDEO      AVMEDIA_TYPE_VIDEO
  
  
  
  int main(int argc, char* argv[])
  
  {   
  
      // initialize FFmpeg library
  
      av_register_all();
  
      //  av_log_set_level(AV_LOG_DEBUG);
  
      int ret;
  
  
  
      // open input file context
  
      AVFormatContext* inctx = nullptr;
  
      //ret = avformat_open_input(&amp;inctx, infile, nullptr, nullptr);
  
      ret = avformat_open_input(&amp;inctx, "C:\\car.mp4", nullptr, nullptr);
  
      // retrive input stream information
  
  
  
  
  
      ret = avformat_find_stream_info(inctx, nullptr);
  
      if (ret &lt; 0) {
  
      std::cerr &lt;&lt; "fail to avformat_find_stream_info: ret=" &lt;&lt; ret;
  
      return 2;
  
      }
  
  
  
      // find primary video stream
  
  
  
  
  
      AVCodec* vcodec = nullptr;
  
      vcodec = avcodec_find_decoder(AV_CODEC_ID_MPEG4);
  
      if (!vcodec) {
  
          fprintf(stderr, "Codec not found\n");
  
          exit(1);
  
      }
  
  
  
      const int vstrm_idx = ret;
  
      AVStream* vstrm = inctx->streams[vstrm_idx];
  
  
  
      // open video decoder context
  
      AVCodecContext *c = NULL;
  
      c = avcodec_alloc_context3(vcodec);
  
      if (!c) {
  
          fprintf(stderr, "Could not allocate video codec context\n");
  
          exit(1);
  
      }
  
  
  
      if (avcodec_open2(c, vcodec, NULL) &lt; 0) {
  
          fprintf(stderr, "Could not open codec\n");
  
          exit(1);
  
      }
  
  
  
      // print input video stream informataion
  
      // initialize sample scaler
  
  
  
      c->pix_fmt = AV_PIX_FMT_YUV420P;
  
      c->width = 1280;
  
      c->height = 720;
  
      if (vcodec->capabilities &amp; CODEC_CAP_TRUNCATED)
  
          c->flags |= CODEC_FLAG_TRUNCATED;
  
  
  
      c->flags2 |= CODEC_FLAG2_FAST;
  
      int width = 1280;
  
      int height = 720;
  
      SwsContext* swsctx = sws_getCachedContext(nullptr, width,
  
          height, AV_PIX_FMT_YUV420P, width, height, AV_PIX_FMT_RGB32,
  
          SWS_FAST_BILINEAR, NULL, NULL, NULL);
  
  }
  
  </vector></iostream>

• I use ffmpeg dinamically to edit a local hosted video to be streamed on iPhone over 3G [on hold]

  3 octobre 2014, par Luchian Chivoiu

  I use ffmpeg dinamically to edit a local hosted video to be streamed on iPhone over 3G .

  I use this line :
  "ffmpeg -i C :\file1.mp4 -s 640x480 -r 30000/1001 -b:a 56k -bt 40k -b:v 50k -maxrate 10M -bufsize 10M -coder 0 -bf 0 -refs 1 -ar 48000 -ab 52k C :\file2.mp4" and it doesn’t work to open on iPhone the transformed file called "file2.mp4".
  I use Web Api and C# to call the ffmpeg locally and the resulted file opens on the browser but still doesn’t want to stream to an iPhone over 3G only if it’s over WiFi.

  Here Apple explains the process but I still didn’t get it work .

  https://developer.apple.com/library/safari/documentation/AppleApplications/Reference/SafariWebContent/CreatingVideoforSafarioniPhone/CreatingVideoforSafarioniPhone.html

  One example that can’t be played on IPhone is this one : http://www.starlety.com/Videos/8ada5277-424a-e411-b2e5-00ff91d7f3dd.mp4

• ffmpeg is reading SDP from RTSP stream but unable to save a screenshot. is it network or utility issue ?

  8 juillet 2017, par Paul Serikov

  My task is to get a screenshot from IP camera rtsp stream via ffmpeg.
  I got following error when I’m trying to do that on DigitalOcean droplet :

  root@docker-512mb-fra1-01:~# ffmpeg -hide_banner -loglevel debug -i rtsp://10.132.193.9//ch0.h264 -f image2 latest.jpg
  
  Splitting the commandline.
  
  Reading option '-hide_banner' ... matched as option 'hide_banner' (do not show program banner) with argument '1'.
  
  Reading option '-loglevel' ... matched as option 'loglevel' (set logging level) with argument 'debug'.
  
  Reading option '-i' ... matched as input url with argument 'rtsp://10.132.193.9//ch0.h264'.
  
  Reading option '-f' ... matched as option 'f' (force format) with argument 'image2'.
  
  Reading option 'latest.jpg' ... matched as output url.
  
  Finished splitting the commandline.
  
  Parsing a group of options: global .
  
  Applying option hide_banner (do not show program banner) with argument 1.
  
  Applying option loglevel (set logging level) with argument debug.
  
  Successfully parsed a group of options.
  
  Parsing a group of options: input url rtsp://10.132.193.9//ch0.h264.
  
  Successfully parsed a group of options.
  
  Opening an input file: rtsp://10.132.193.9//ch0.h264.
  
  [rtsp @ 0x1298440] SDP:
  
  v=0
  
  o=- 1499314217993040 1 IN IP4 192.168.1.128
  
  s=H.264 Program Stream, streamed by the LIVE555 Media Server
  
  i=ch0.h264
  
  t=0 0
  
  a=DevVer:pusher2
  
  a=GroupName:IPCAM
  
  a=NickName:CIF
  
  a=CfgSection:PROG_CHN0
  
  a=tool:LIVE555 Streaming Media v2011.08.13
  
  a=type:broadcast
  
  a=control:*
  
  a=range:npt=0-
  
  a=x-qt-text-nam:H.264 Program Stream, streamed by the LIVE555 Media Server
  
  a=x-qt-text-inf:ch0.h264
  
  m=video 0 RTP/AVP 96
  
  c=IN IP4 0.0.0.0
  
  b=AS:4000
  
  a=rtpmap:96 H264/90000
  
  a=control:trackID=1
  
  a=fmtp:96 packetization-mode=1;profile-level-id=64001F;sprop-parameter-sets=Z2QAH6wrUCgC3IA=,aO48MA==
  
  a=framesize:96 1280-720
  
  a=cliprect:0,0,1280,720
  
  m=audio 0 RTP/AVP 97
  
  a=rtpmap:97 mpeg4-generic/8000/2
  
  a=fmtp:97 streamtype=5;profile-level-id=1;cpresent=0;mode=AAC-hbr;sizelength=13;indexlength=3;indexdeltalength=3;config=1590
  
  a=control:trackID=2
  
  
  
  Failed to parse interval end specification ''
  
  [rtsp @ 0x1298440] video codec set to: h264
  
  [rtsp @ 0x1298440] RTP Packetization Mode: 1
  
  [rtsp @ 0x1298440] RTP Profile IDC: 64 Profile IOP: 0 Level: 1f
  
  [rtsp @ 0x1298440] Extradata set to 0x1298a20 (size: 23)
  
  [rtsp @ 0x1298440] audio codec set to: aac
  
  [rtsp @ 0x1298440] audio samplerate set to: 8000
  
  [rtsp @ 0x1298440] audio channels set to: 2
  
  [udp @ 0x129e7e0] end receive buffer size reported is 131072
  
  [udp @ 0x129e680] end receive buffer size reported is 131072
  
  [udp @ 0x12bf380] end receive buffer size reported is 131072
  
  [udp @ 0x12bf1c0] end receive buffer size reported is 131072
  
  [rtsp @ 0x1298440] hello state=0
  
  [rtsp @ 0x1298440] UDP timeout, retrying with TCP
  
  [rtsp @ 0x1298440] hello state=0
  
  [rtsp @ 0x1298440] Could not find codec parameters for stream 0 (Video: h264, 1 reference frame, none(left), 1280x720, 1/180000): unspecified pixel format
  
  Consider increasing the value for the 'analyzeduration' and 'probesize' options
  
  Input #0, rtsp, from 'rtsp://10.132.193.9//ch0.h264':
  
    Metadata:
  
      title           : H.264 Program Stream, streamed by the LIVE555 Media Server
  
      comment         : ch0.h264
  
    Duration: N/A, start: 0.000000, bitrate: N/A
  
      Stream #0:0, 0, 1/90000: Video: h264, 1 reference frame, none(left), 1280x720, 1/180000, 90k tbr, 90k tbn, 180k tbc
  
      Stream #0:1, 0, 1/8000: Audio: aac, 8000 Hz, stereo, fltp
  
  Successfully opened the file.
  
  Parsing a group of options: output url latest.jpg.
  
  Applying option f (force format) with argument image2.
  
  Successfully parsed a group of options.
  
  Opening an output file: latest.jpg.
  
  Successfully opened the file.
  
  detected 1 logical cores
  
  [graph 0 input from stream 0:0 @ 0x1298280] Setting 'video_size' to value '1280x720'
  
  [graph 0 input from stream 0:0 @ 0x1298280] Setting 'pix_fmt' to value '-1'
  
  [buffer @ 0x12f9680] Unable to parse option value "-1" as pixel format
  
  [graph 0 input from stream 0:0 @ 0x1298280] Setting 'time_base' to value '1/90000'
  
  [graph 0 input from stream 0:0 @ 0x1298280] Setting 'pixel_aspect' to value '0/1'
  
  [graph 0 input from stream 0:0 @ 0x1298280] Setting 'sws_param' to value 'flags=2'
  
  [graph 0 input from stream 0:0 @ 0x1298280] Setting 'frame_rate' to value '180000/2'
  
  [buffer @ 0x12f9680] Unable to parse option value "-1" as pixel format
  
  [buffer @ 0x12f9680] Error setting option pix_fmt to value -1.
  
  [graph 0 input from stream 0:0 @ 0x1298280] Error applying options to the filter.
  
  Error opening filters!
  
  Exiting normally, received signal 2.

  As you see, ffmpeg is able to read SDP metadata, but for some reason is unable to save a screenshot

  Also same command works fine on my laptop with same VPN configuration !

  Just in case, IP camera doesn’t have a public IP address and accessible via VPN.

  What could be wrong and how to debug ?

  I tried to increase -analyzeduration and -probesize options from default 5s to 30s, but it doesn’t work.