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• Extremely slow ffmpeg/sws_scale() - only on heavy duty

  28 septembre 2020, par user2328447

  I am writing a video player using ffmpeg (Windows only, Visual Studio 2015, 64 bit compile).
With common videos (up to 4K @ 30FPS), it works pretty good. But with my maximum target - 4K @ 60FPS, it fails. Decoding still is fast enough, but when it comes to YUV/BGRA conversion it is simply not fast enough, even though it's done in 16 threads (one thread per frame on a 16/32 core machine).

  



  So as a first countermeasure I skipped the conversion of some frames and got a stable frame rate of 40 that way. Comparing the two versions in Concurrency Visualizer, I found a strange issue I don't know the reason of.

  



  .

  



  Here's an image of the frameskip version :

You see that the conversion is pretty quick (average roughly 35ms)
Thus, as multiple threads are used, it also should be quick enough for 60FPS, but it isn't !

  



  .

  



  The image of the non-frameskip version shows why :

The conversion of a single frame has become ten times slower than before (average roughly 350ms). Now a heavy workload on many cores would of course cause a minor slowdown per core due to reduced turbo - let's say 10 or 20%. But never an extreme slowdown of 1000%.

  



  .

  



  Interesting detail is, that the stack trace of the non-frameskip version shows some system activity I don't really understand - beginning with ntoskrnl.exe!KiPageFault+0x373. There are no exceptions, other error messages or such - it just becomes extremely slow.

  



  Edit : A colleague just told me that this looks like a memory problem with paged-out memory at first glance - but my memory utilization is low (below 1GB, and more than 20GB free)

  



  Can anyone tell me what could be causing this ?

  


• Open CV Codec FFMPEG Error fallback to use tag 0x7634706d/'mp4v'

  22 mai 2019, par Cohen

  Doing a filter recording and all is fine. The code is running, but at the end the video is not saved as MP4. I have this error :

  OpenCV: FFMPEG: tag 0x44495658/'XVID' is not supported with codec id 12 and format 'mp4 / MP4 (MPEG-4 Part 14)'
  
  OpenCV: FFMPEG: fallback to use tag 0x7634706d/'mp4v'

  Using a MAC and the code is running correctly, but is not saving. I tried to find more details about this error, but wasn’t so fortunate. I use as editor Sublime. The code run on Atom tough but is giving this error :

  OpenCV: FFMPEG: tag 0x44495658/'XVID' is not supported with codec id 12 and format 'mp4 / MP4 (MPEG-4 Part 14)'
  
  OpenCV: FFMPEG: fallback to use tag 0x7634706d/'mp4v'
  
  2018-05-28 15:04:25.274 Python[17483:2224774] AVF: AVAssetWriter status: Cannot create file

  ....

  import numpy as np
  
  import cv2
  
  import random
  
  from utils import CFEVideoConf, image_resize
  
  import glob
  
  import math
  
  
  
  
  
  cap = cv2.VideoCapture(0)
  
  
  
  frames_per_seconds = 24
  
  save_path='saved-media/filter.mp4'
  
  config = CFEVideoConf(cap, filepath=save_path, res='360p')
  
  out = cv2.VideoWriter(save_path, config.video_type, frames_per_seconds, config.dims)
  
  
  
  
  
  def verify_alpha_channel(frame):
  
      try:
  
          frame.shape[3] # looking for the alpha channel
  
      except IndexError:
  
          frame = cv2.cvtColor(frame, cv2.COLOR_BGR2BGRA)
  
      return frame
  
  
  
  
  
  def apply_hue_saturation(frame, alpha, beta):
  
      hsv_image = cv2.cvtColor(frame, cv2.COLOR_BGR2HSV)
  
      h, s, v = cv2.split(hsv_image)
  
      s.fill(199)
  
      v.fill(255)
  
      hsv_image = cv2.merge([h, s, v])
  
  
  
      out = cv2.cvtColor(hsv_image, cv2.COLOR_HSV2BGR)
  
      frame = verify_alpha_channel(frame)
  
      out = verify_alpha_channel(out)
  
      cv2.addWeighted(out, 0.25, frame, 1.0, .23, frame)
  
      return frame
  
  
  
  
  
  def apply_color_overlay(frame, intensity=0.5, blue=0, green=0, red=0):
  
      frame = verify_alpha_channel(frame)
  
      frame_h, frame_w, frame_c = frame.shape
  
      sepia_bgra = (blue, green, red, 1)
  
      overlay = np.full((frame_h, frame_w, 4), sepia_bgra, dtype='uint8')
  
      cv2.addWeighted(overlay, intensity, frame, 1.0, 0, frame)
  
      return frame
  
  
  
  
  
  def apply_sepia(frame, intensity=0.5):
  
      frame = verify_alpha_channel(frame)
  
      frame_h, frame_w, frame_c = frame.shape
  
      sepia_bgra = (20, 66, 112, 1)
  
      overlay = np.full((frame_h, frame_w, 4), sepia_bgra, dtype='uint8')
  
      cv2.addWeighted(overlay, intensity, frame, 1.0, 0, frame)
  
      return frame
  
  
  
  
  
  def alpha_blend(frame_1, frame_2, mask):
  
      alpha = mask/255.0 
  
      blended = cv2.convertScaleAbs(frame_1*(1-alpha) + frame_2*alpha)
  
      return blended
  
  
  
  
  
  def apply_circle_focus_blur(frame, intensity=0.2):
  
      frame = verify_alpha_channel(frame)
  
      frame_h, frame_w, frame_c = frame.shape
  
      y = int(frame_h/2)
  
      x = int(frame_w/2)
  
  
  
      mask = np.zeros((frame_h, frame_w, 4), dtype='uint8')
  
      cv2.circle(mask, (x, y), int(y/2), (255,255,255), -1, cv2.LINE_AA)
  
      mask = cv2.GaussianBlur(mask, (21,21),11 )
  
  
  
      blured = cv2.GaussianBlur(frame, (21,21), 11)
  
      blended = alpha_blend(frame, blured, 255-mask)
  
      frame = cv2.cvtColor(blended, cv2.COLOR_BGRA2BGR)
  
      return frame
  
  
  
  
  
  def portrait_mode(frame):
  
      cv2.imshow('frame', frame)
  
      gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
  
      _, mask = cv2.threshold(gray, 120,255,cv2.THRESH_BINARY)
  
  
  
      mask = cv2.cvtColor(mask, cv2.COLOR_GRAY2BGRA)
  
      blured = cv2.GaussianBlur(frame, (21,21), 11)
  
      blended = alpha_blend(frame, blured, mask)
  
      frame = cv2.cvtColor(blended, cv2.COLOR_BGRA2BGR)
  
      return frame
  
  
  
  
  
  def apply_invert(frame):
  
      return cv2.bitwise_not(frame)
  
  
  
  while(True):
  
      # Capture frame-by-frame
  
      ret, frame = cap.read()
  
      frame = cv2.cvtColor(frame, cv2.COLOR_BGR2BGRA) 
  
      #cv2.imshow('frame',frame)
  
  
  
  
  
      hue_sat = apply_hue_saturation(frame.copy(), alpha=3, beta=3)
  
      cv2.imshow('hue_sat', hue_sat)
  
  
  
      sepia = apply_sepia(frame.copy(), intensity=.8)
  
      cv2.imshow('sepia',sepia)
  
  
  
      color_overlay = apply_color_overlay(frame.copy(), intensity=.8, red=123, green=231)
  
      cv2.imshow('color_overlay',color_overlay)
  
  
  
      invert = apply_invert(frame.copy())
  
      cv2.imshow('invert', invert)
  
  
  
      blur_mask = apply_circle_focus_blur(frame.copy())
  
      cv2.imshow('blur_mask', blur_mask)
  
  
  
      portrait = portrait_mode(frame.copy())
  
      cv2.imshow('portrait',portrait)
  
  
  
      if cv2.waitKey(20) & 0xFF == ord('q'):
  
          break
  
  
  
  # When everything done, release the capture
  
  cap.release()
  
  cv2.destroyAllWindows()

• Trouble getting video stream from Bebop 2 (python, open cv and ffmpeg)

  20 décembre 2018, par Seb A

  I’m currently working with the Bebop 2 drone from parrot and I would like to get the video stream from the bebop and to use the frame I get. To control the bebop I’m using this library : https://github.com/amymcgovern/pyparrot.

  First I’ve tried to use opencv by opening the sdp file used by the bebop to stream the video with this code :

  capture = cv2.VideoCapture('./bebop.sdp')
  
  
  
      while True :
  
          rt,img = capture.read()
  
          cv2.imshow("cam",img)
  
          cv2.waitKey(10)

  here is the content of the sdp file :

  c=IN IP4 192.168.42.1
  
  m=video 55004 RTP/AVP 96
  
  a=rtpmap:96 H264/90000

  but I got this error

  [rtp @ 0000020b890b3300] Protocol 'rtp' not on whitelist 'file,crypto'!
  
  warning: Error opening file (/build/opencv/modules/videoio/src/cap_ffmpeg_impl.hpp:808)
  
  warning: ./bebop.sdp (/build/opencv/modules/videoio/src/cap_ffmpeg_impl.hpp:809)
  
  False
  
  OpenCV Error: Assertion failed (size.width>0 && size.height>0) in cv::imshow, file C:\projects\opencv-python\opencv\modules\highgui\src\window.cpp, line 331
  
  Traceback (most recent call last):
  
   File "pilotage.py", line 109, in <module>
  
     _main_(args)
  
   File "pilotage.py", line 56, in main
  
     cv2.imshow('drone view',im)
  
  cv2.error: C:\projects\opencv-python\opencv\modules\highgui\src\window.cpp:331: error: (-215) size.width>0 &amp;&amp; size.height>0 in function cv::imshow
  
  </module>

  I’ve seen that this is due to the ffmpeg command used by opencv that does not include the option -protocol_whitelist
  So I tried to get the image directly with ffmpeg by using this command

  "ffmpeg -protocol_whitelist \"file,rtp,udp\"  -i  ./bebop.sdp -r 30 -b:v 800k image_%03d.png &"

  But the images I got were awful and useless.
  Like this one :
  

  So I tried different options to improve the quality but I can’t get it to work.
  Thanks for your help.

  I’m on windows 10 and using latest python version