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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.

• fastest ffmpeg without caring about quality

  31 mai 2019, par RedDeath

  I would like to convert any video into .mp4 as fast as possible without caring about quality loss. I have used the next commands with which I have been able to finish the process in 37 seconds for a 10 second video.

  -vcodec h264
  
  -crf 32
  
  -preset ultrafast

  However 37 seconds is still too long for a 10 seconds video. Is there any improvements that I can do to the command in order to reduce the execution time ?

  ---

  Edit (Extra info) :

  I’m using FFmpeg Android (implementation 'com.writingminds:FFmpegAndroid:0.3.2') even though commands usually work for any FFmpeg (with a few variants depending on the FFmpeg version).

  The command used in my case which gave me the fastest result so far is :

      mFfmpeg.execute(
  
          arrayOf(
  
              "-i" , videoCopy?.path,
  
              "-vcodec", "h264",
  
              "-crf", "32",
  
              "-preset", "ultrafast",
  
              "-y", uploadFile?.path), 
  
          object : ExecuteBinaryResponseHandler() { ... }

  Which for regular FFmpeg command would be

  "-ffmpeg -i {video?.path} -vcodec h264 -crf 32 -preset ultrafast -y {uploadFile?.path}"

  Where video is my original video File and uploadFile is the File where I want to save the result into.

  In a Samsung J3 (SM-J320M, you can find its specifications online) such command takes the aforementioned 37 seconds.

  After executing such command the first onProgress message returned by FFmpeg prints :

  ffmpeg version n3.0.1 Copyright (c) 2000-2016 the FFmpeg developers  built with gcc 4.8 (GCC)  
  
  configuration: 
  
      --target-os=linux 
  
      --cross-prefix=/home/vagrant/SourceCode/ffmpeg-android/toolchain-android/bin/arm-linux-androideabi- 
  
      --arch=arm 
  
      --cpu=cortex-a8 
  
      --enable-runtime-cpudetect 
  
      --sysroot=/home/vagrant/SourceCode/ffmpeg-android/toolchain-android/sysroot 
  
      --enable-pic 
  
      --enable-libx264 
  
      --enable-libass 
  
      --enable-libfreetype 
  
      --enable-libfribidi 
  
      --enable-libmp3lame 
  
      --enable-fontconfig 
  
      --enable-pthreads 
  
      --disable-debug 
  
      --disable-ffserver 
  
      --enable-version3 
  
      --enable-hardcoded-tables 
  
      --disable-ffplay 
  
      --disable-ffprobe 
  
      --enable-gpl 
  
      --enable-yasm 
  
      --disable-doc 
  
      --disable-shared 
  
      --enable-static 
  
      --pkg-config=/home/vagrant/SourceCode/ffmpeg-android/ffmpeg-pkg-config 
  
      --prefix=/home/vagrant/SourceCode/ffmpeg-android/build/armeabi-v7a 
  
      --extra-cflags='-I/home/vagrant/SourceCode/ffmpeg-android/toolchain-android/include -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -fno-strict-overflow -fstack-protector-all' 
  
      --extra-ldflags='-L/home/vagrant/SourceCode/ffmpeg-android/toolchain-android/lib -Wl,-z,relro -Wl,-z,now -pie' 
  
      --extra-libs='-lpng -lexpat -lm' 
  
      --extra-cxxflags=  
  
          libavutil    55. 17.103 / 55. 17.103  
  
          libavcodec    57. 24.102 / 57. 24.102
  
          libavformat    57. 25.100 / 57. 25.100  
  
          libavdevice    57.  0.101 / 57.  0.101  
  
          libavfilter    6. 31.100 /  6. 31.100  
  
          libswscale      4.  0.100 /  4.  0.100  
  
          libswresample   2.  0.101 /  2.  0.101  
  
          libpostproc    54.  0.100 / 54.  0.100
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/storage/emulated/0/DCIM/Yakatak/656.mp4':  Metadata:    major_brand     : mp42    minor_version   : 0    compatible_brands: isommp42    creation_time   : 2019-05-29 11:27:56    location        : +51.5202-000.1435/    location-eng    : +51.5202-000.1435/  Duration: 00:00:09.47, start: 0.000000, bitrate: 12147 kb/s    Stream #0:0(eng): Video: h264 (Constrained Baseline) (avc1 / 0x31637661), yuv420p, 1280x720, 11899 kb/s, 30.02 fps, 30 tbr, 90k tbn, 180k tbc (default)    Metadata:      rotate          : 90      creation_time   : 2019-05-29 11:27:56      handler_name    : VideoHandle    Side data:      displaymatrix: rotation of -90.00 degrees    Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 256 kb/s (default)    Metadata:      creation_time   : 2019-05-29 11:27:56      handler_name    : SoundHandle[libx264 @ 0xb5428800] using cpu capabilities: none![libx264 @ 0xb5428800] profile Constrained Baseline, level 3.1[libx264 @ 0xb5428800] 264 - core 148 - H.264/MPEG-4 AVC codec - Copyleft 2003-2015 - http://www.videolan.org/x264.html - options: cabac=0 ref=1 deblock=0:0:0 analyse=0:0 me=dia subme=0 psy=1 psy_rd=1.00:0.00 mixed_ref=0 me_range=16 chroma_me=1 trellis=0 8x8dct=0 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=0 threads=6 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=0 weightp=0 keyint=250 keyint_min=25 scenecut=0 intra_refresh=0 rc=crf mbtree=0 crf=32.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=0
  
  
  
  Output #0, mp4, to '/storage/emulated/0/DCIM/Yakatak/uploadFile.mp4':  Metadata:    major_brand     : mp42    minor_version   : 0    compatible_brands: isommp42    location-eng    : +51.5202-000.1435/    location        : +51.5202-000.1435/    encoder         : Lavf57.25.100    Stream #0:0(eng): Video: h264 (libx264) ([33][0][0][0] / 0x0021), yuv420p, 720x1280, q=-1--1, 30 fps, 15360 tbn, 30 tbc (default)    Metadata:      handler_name    : VideoHandle      creation_time   : 2019-05-29 11:27:56      encoder         : Lavc57.24.102 libx264    Side data:      unknown side data type 10 (24 bytes)    Stream #0:1(eng): Audio: aac (LC) ([64][0][0][0] / 0x0040), 48000 Hz, stereo, fltp, 128 kb/s (default)    Metadata:      creation_time   : 2019-05-29 11:27:56      handler_name    : SoundHandle      encoder         : Lavc57.24.102 aacStream mapping:  Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264))  Stream #0:1 -> #0:1 (aac (native) -> aac (native))Press [q] to stop, [?] for helpframe=    0 fps=0.0

• How to plot an animated graph

  2 août 2019, par Mukonza Sabastian Simbarashe

  Following along How to Create Animated Graphs in Python when constructing an animated plot then on writing the ffmpeg I get the following error :

  'Requested MovieWriter ({}) not available'.format(name))
  
  RuntimeError: Requested MovieWriter (ffmpeg) not available

  After getting this error, I initially tried to install ffmpeg using pip by the following method :

  python -m install ffmpeg

  and it seems to have successfully installed ffmpeg, but going back to my code I still get the same error

  Find below my code :

  import numpy as np
  
  import pandas as pd
  
  import seaborn as sns
  
  import matplotlib
  
  import matplotlib.pyplot as plt
  
  import matplotlib.animation as animation
  
  
  
  overdoses = pd.read_excel(r'C:\Users\ACER\Desktop\overdose_data_1999-2015.xls',sheet_name='Online',skiprows =6)
  
  
  
  def get_data(table,rownum,title):
  
      data = pd.DataFrame(table.loc[rownum][2:]).astype(float)
  
      data.columns = {title}
  
      return data
  
  
  
  title = 'Heroin Overdoses'
  
  d = get_data(overdoses,18,title)
  
  x = np.array(d.index)
  
  y = np.array(d['Heroin Overdoses'])
  
  overdose = pd.DataFrame(y,x)
  
  overdose.columns = {title}
  
  Writer = animation.writers['ffmpeg']

  Here is the stack trace :

  Traceback (most recent call last):
  
    File "C:\Python\Python36\lib\site-packages\matplotlib\animation.py", line 161, in __getitem__
  
      return self.avail[name]
  
  KeyError: 'ffmpeg'
  
  
  
  During handling of the above exception, another exception occurred:
  
  
  
  Traceback (most recent call last):
  
    File "", line 1, in <module>
  
      Writer = animation.writers['ffmpeg']
  
    File "C:\Python\Python36\lib\site-packages\matplotlib\animation.py", line 164, in __getitem__
  
      'Requested MovieWriter ({}) not available'.format(name))
  
  RuntimeError: Requested MovieWriter (ffmpeg) not available
  
  </module>