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• RTP/UDP or RTSP for accessing stream and passing frame to OpenCV ?

  15 janvier 2020, par xor31four

  Apologies for my inexperience in this domain..I am trying to implement an algorithm that detects the occurrence of a particular event in real-time. The particular event is a consecutive growth of motion across 5 consecutive frames.. almost analogous to a growing sphere or beach ball.

  I am able to detect the event on pre-recorded video that is in .avi format (mjpeg frames) with EmguCV (C# wrapper for OpenCV). The method I use is based on background subtraction.. outlined here https://www.pyimagesearch.com/2015/05/25/basic-motion-detection-and-tracking-with-python-and-opencv/

  The problem is that the live video transport stream is usually in the format rtsp ://XXX.XXX.X.XX/stream1.sdp

  EmguCV on windows can’t decode this h.264 stream for some reason that I am still trying to figure out ... I tried the same url using Python and OpenCV and received a non-matching transport in server reply message similar to this one "Nonmatching transport in server reply" when cv2.VideoCapture rtsp onvif camera, how to fix ? - the answer didn’t work for me.

  I can open the rtsp URL using VLCPlayer and its corresponding C# library - from my understanding it is using ffmpeg, although I may be wrong. FFmpeg on the command line can access the stream.

  EmguCV also uses ffmpeg as a backend which is why I am very confused as to why it can’t open the rtsp URL.

  Here is an image of the module tree when VLCPlayer opens the rtsp stream : .

  From my understanding, EmguCV doesn’t use live555 or avcodec..

  I’ve noticed that if I change the streamer configuration to use UDP or RTP rather than RTSP, EmguCV can access the h.264 URL, although the URL is now in the format rtp/udp ://XXX.XXX.X.XX:XXXXX - no .sdp extension.

  I would highly appreciate if someone with more experience can give me some pointers.
  I have a great deal to learn even though I have spent a lot of time researching this topic. In regards to the detections remaining successful would it be recommended to process H.264 frames with possible distortion or MJPEG frames ?

  I can’t afford a delay longer than 1-2 seconds, and would ideally like to continue with the current method used to detect the event.

  From my current understanding, here are the routes I can take :

  1) Use RTP/UDP and process h.264 video using EmguCV - there is some distortion in the video when there is a large amount of movement.. I also receive several h264 error messages during the stream

  [h264 @ 00000124f13a5080] SPS unavailable in decode_picture_timing
  
  [h264 @ 00000124f13a5080] non-existing PPS 0 referenced
  
  [h264 @ 00000124f13a5080] decode_slice_header error
  
  [h264 @ 00000124f13a5080] no frame!
  
  [h264 @ 00000124f135eac0] Missing reference picture, default is 0
  
  [h264 @ 00000124f135eac0] decode_slice_header error
  
  [h264 @ 00000124f13a5080] cbp too large (6929) at 11 20
  
  [h264 @ 00000124f13a5080] error while decoding MB 11 20
  
  [h264 @ 00000124f135eac0] top block unavailable for requested intra mode -1
  
  [h264 @ 00000124f135eac0] error while decoding MB 3 0
  
  [h264 @ 00000124f124e580] cbp too large (96) at 33 0
  
  [h264 @ 00000124f124e580] error while decoding MB 33 0
  
  [h264 @ 00000124f19940c0] top block unavailable for requested intra mode
  
  [h264 @ 00000124f19940c0] error while decoding MB 1 1

  

  2) Keep RTSP protocol, use libav to decode the frames and pass to EmguCV.. following this answer https://www.raspberrypi.org/forums/viewtopic.php?t=83127 .. I’m not sure if this will introduce a huge delay

  3) Keep RTSP protocol, use ffmpeg to convert h.264 stream to MJPEG and access this URL instead ?
  Again I’m not sure if this will be a feasible solution if it will introduce a great delay.

  4) Use a Linux machine rather than windows and configure a gstreamer backend - not ideal

  Thank you for taking the time to read this post.

• FFMPEG on ubuntu wont start. Process is just killed [on hold]

  8 novembre 2018, par AK47

  I am trying to run a command on ffmpeg. When I run on my local computer it works fine but when running on my ubuntu server it won’t start. It just keeps giving an error saying the process is killed when it trys to start. Is this something related to memory or a different issue ?

  Killed   14 fps=0.0 q=0.0 size=       0kB time=00:00:00.00 bitrate=N/A dup=2 drop=0 speed=   0x

  Any help would be greatly appreciated

  Below are logs that are thrown.

  root@kickpush:/var/www/kick-push.co.uk/public_html/allblacks# ffmpeg -loop 1 -i q.png -r 30 -t 10 -i a.png -r 30 -t 5 image2.mp4
  
  ffmpeg version 3.3.3 Copyright (c) 2000-2017 the FFmpeg developers
  
    built with gcc 4.8 (Ubuntu 4.8.4-2ubuntu1~14.04.3)
  
    configuration: --extra-libs=-ldl --prefix=/opt/ffmpeg --mandir=/usr/share/man --enable-avresample --disable-debug --enable-nonfree --enable-gpl --enable-version3 --enable-libopencore-amrnb --enable-libopencore-amrwb --disable-decoder=amrnb --disable-decoder=amrwb --enable-libpulse --enable-libfreetype --enable-gnutls --disable-ffserver--enable-libx264 --enable-libx265 --enable-libfdk-aac --enable-libvorbis --enable-libtheora --enable-libmp3lame --enable-libopus --enable-libvpx --enable-libspeex --enable-libass --enable-avisynth --enable-libsoxr --enable-libxvid --enable-libvidstab --enable-libwavpack --enable-nvenc --enable-libzimg
  
    libavutil      55. 58.100 / 55. 58.100
  
    libavcodec     57. 89.100 / 57. 89.100
  
    libavformat    57. 71.100 / 57. 71.100
  
    libavdevice    57.  6.100 / 57.  6.100
  
    libavfilter     6. 82.100 /  6. 82.100
  
    libavresample   3.  5.  0 /  3.  5.  0
  
    libswscale      4.  6.100 /  4.  6.100
  
    libswresample   2.  7.100 /  2.  7.100
  
    libpostproc    54.  5.100 / 54.  5.100
  
  Input #0, png_pipe, from 'q.png':
  
    Duration: N/A, bitrate: N/A
  
      Stream #0:0: Video: png, rgba(pc), 1080x1920, 25 fps, 25 tbr, 25 tbn, 25 tbc
  
  Input #1, png_pipe, from 'a.png':
  
    Duration: N/A, bitrate: N/A
  
      Stream #1:0: Video: png, rgba(pc), 1080x1920, 25 tbr, 25 tbn, 25 tbc
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (png (native) -> h264 (libx264))
  
  Press [q] to stop, [?] for help
  
  No pixel format specified, yuv444p for H.264 encoding chosen.
  
  Use -pix_fmt yuv420p for compatibility with outdated media players.
  
  [libx264 @ 0x31a4a40] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 AVX2 LZCNT BMI2
  
  [libx264 @ 0x31a4a40] profile High 4:4:4 Predictive, level 4.0, 4:4:4 8-bit
  
  [libx264 @ 0x31a4a40] 264 - core 148 r2643 5c65704 - H.264/MPEG-4 AVC codec - Copyleft 2003-2015 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=4 threads=1 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
  
  Output #0, mp4, to 'image2.mp4':
  
    Metadata:
  
      encoder         : Lavf57.71.100
  
      Stream #0:0: Video: h264 (libx264) ([33][0][0][0] / 0x0021), yuv444p, 1080x1920, q=-1--1, 30 fps, 15360 tbn, 30 tbc
  
      Metadata:
  
        encoder         : Lavc57.89.100 libx264
  
      Side data:
  
        cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: -1
  
  Killed   14 fps=0.0 q=0.0 size=       0kB time=00:00:00.00 bitrate=N/A dup=2 drop=0 speed=   0x

• FFMpeg(Android) av_read_frame or avcodec_decode_video2 returning same colour

  5 décembre 2012, par Cehm

  I've been experimenting FFMpeg for the past 2 weeks and I'm having a bit of trouble...
  First I've been working with a Galaxy S3, which worked super fine, gave me the best pictures ever but I recently switched to a Galaxy NEXUS which gave me a bunch of problems...

  What I'm doing : I just extract frame from a video

  How I'm doing :

  while(av_read_frame(gFormatCtx, &packet)>=0)
  
          {
  
              // Is this a packet from the video stream?
  
              if(packet.stream_index==videoStream)
  
              {
  
                  // Decode video frame
  
                  avcodec_decode_video2(gVideoCodecCtx, pFrame, &frameFinished, &packet);
  
                  // Did we get a video frame?
  
                  if(frameFinished)
  
                  {//and so on... But our problem is already here...

  Ok, now pFrame is holding a YUV representation of my frame... So, in order to check what I'm getting from the avcodec_decode_video2(...) function I'm just writing pFrame to a file so I can see it with any YUV reader on the web.

  char yuvFileName[100];
  
  sprintf(yuvFileName,"/storage/sdcard0/yuv%d.yuv",index);
  
  FILE* fp = fopen(yuvFileName, "wb");
  
  int y;
  
  // Write pixel data
  
  for(y=0; yheight; y++)
  
  {
  
      fwrite(pFrame->data[0]+y*pFrame->linesize[0], 1, gVideoCodecCtx->width, fp);    
  
  }
  
  for(y=0; yheight/2; y++)
  
  {
  
      fwrite(pFrame->data[1]+y*pFrame->linesize[1], 1, gVideoCodecCtx->width/2, fp);
  
  }
  
  for(y=0; yheight/2; y++)
  
  {
  
      fwrite(pFrame->data[2]+y*pFrame->linesize[2], 1, gVideoCodecCtx->width/2, fp);
  
  }
  
  fclose(fp);

  Ok so Here I now have my result on a file store @ /storage/sdcard0/blabla.YUV on my Galaxy Nexus root memory.

  But If I open the file with (for example XnView, which is meant to display YUV type properly) I only see Dark green on the picture.

  What bothers me is that everything worked properly on Galaxy S3 but something failed on GNexus...

  So here's my question : Why doesn't it work on Galaxy Nexus ?

  Compatibility problem between Gnexus and armeabiv7 ?

  I don't know !

  Regards,
  Cehm