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• I created a Python code to capture live video using FFmpeg, but the output screen only shows noise

  16 octobre 2024, par chun3 hyun

  The code below is Python code that made my computer screen video capture in real time via ffmpeg.

  


  When I run the code below, it goes well until a new window named 'Captured Frame' is created. But this 'Captured Frame' window doesn't show the full screen of my computer, and the gray screen is generating a lot of noise.

  


  import cv2
import numpy as np
import subprocess

def frame_capture():
    # Set FFmpeg command (capture desired window or area)
    ffmpeg_command = [
        'ffmpeg',
        '-f', 'gdigrab',  # Windows screen capture (using gdigrab)
        '-framerate', '30',  # Setting the Frame Speed
        '-i', 'desktop',  # What to capture (for example, full screen)
        '-pix_fmt', 'bgr0',
        '-vcodec', 'rawvideo',  # Video codec settings
        '-tune', 'zerolatency',
        '-an',  # Disable audio
        '-sn',  # Disable Caption
        '-f', 'rawvideo', '-'
    ]

    # Running the FFmpeg process
    process = subprocess.Popen(ffmpeg_command, stdout=subprocess.PIPE, bufsize=10**8)

    while True:
        # Read Frame from FFmpeg (Resolution Example: 1920x1080)
        raw_frame = process.stdout.read(1920 * 1080 * 3)  # 1920x1080 resolution, BGR format
        if not raw_frame:
            break  # Shut down the loop when you can no longer receive frames

        # Converting frame data to a numpy array
        frame = np.frombuffer(raw_frame, np.uint8).reshape((1080, 1920, 3))

        # Add frame processing code here
        # Example: Showing a frame on the screen
        cv2.imshow('Captured Frame', frame)

        # Press the 'q' key to end
        if cv2.waitKey(1) & 0xFF == ord('q'):
            break

    # End of process and release of resources
    process.stdout.close()
    process.wait()
    cv2.destroyAllWindows()
frame_capture()


  


  What could I have done wrong ? When I directly input the FFmpeg command in the Windows command prompt(knows as 'cmd') as shown below to save the video (in .mp4 format), I can see that the screen is output normally in the saved file. It seems that FFmpeg itself is installed correctly, but I don't know what the cause is.

  


  hwnd=132554 -pix_fmt yuv420p -vf "scale=iw-mod(iw\,2):ih-mod(ih\,2)" -draw_mouse 1 -t 10 output.mp4


  


  The handle number written above was the handle of the active Chrome window on my computer.

  


  My ffmpeg version is 2024-10-10-git-0f5592cfc7-full_build-www.gyan.dev My Python version is 3.12.4
My Windows version and build are as specified below.
:Windows 11 Home, 10.0.22631

  


  Capturing the computer screen with FFmpeg. I tried it, but the output screen shows only noise.

  


• libavcodec.so.58 not found when running software compiled with opencv

  22 avril, par Abinaya

  I am using ubuntu 22.04. Now every time I try to run software compiled with Opencv, I get the following error :

  


  `libavcodec.so.58 => not found
 libavformat.so.58 => not found
 libavutil.so.56 => not found
 libswscale.so.5 => not found
`


  


  Looking around /lib/x86_64-linux-gnu/, I can find libavcodec.so.59, but not libavcodec.so.58.

  


  When trying to run sudo apt-get install libavcodec58, I get :

  


  Package 'libavcodec58' has no installation candidate

  


  I've scoured the internet in search of an answer, but could not find anything at this point. Any help with solving this problem will be very much appreciated.

  


  I have tried to recreate symbolic link with
'ls -l libavcodec.so.59'
1 root root 23 Aug 10 2024 libavcodec.so.59 ->libavcodec.so.59.37.100`

  


  'dconfig -vl libavcodec.so.59.37.100'
libavcodec.so.59 -> libavcodec.so.59.37.100`

  


  But I am still struck

  


• avutil : Fix linking x86 asm constants with Clang in MSVC mode

  12 juin, par Martin Storsjö

  avutil : Fix linking x86 asm constants with Clang in MSVC mode
  This fixes building with Clang in MSVC mode, for x86, which was
  
  broken in 6e49b8699657b808b7dc80033f2c3f2d0e029fa3 (in Nov 2024) ;
  
  previously it failed with undefined symbols for the constants
  
  defined with DECLARE_ASM_CONST, accessed via inline assembly.
  Before 57861911a34e1c33796be97f2b2f44e05fffd647, there was an
  
      #elif defined(__GNUC__) || defined(__clang__)
  
  case before the
  
      #elif defined(_MSC_VER)
  
  case for defining DECLARE_ASM_CONST, which included av_used.
  
  (This case included the explicit "defined(__clang__)" since
  
  f637046d3134a331e4b5a7243ac3dfb92735b8a5.)
  After 57861911a34e1c33796be97f2b2f44e05fffd647, it used the
  
  generic definition of DECLARE_ASM_CONST that also included
  
  av_used - which also worked for Clang in MSVC mode. But after
  
  6e49b8699657b808b7dc80033f2c3f2d0e029fa3, Clang in MSVC mode
  
  ended up using the MSVC specific variant which lacked the
  
  av_used declaration, causing linker errors due to undefined
  
  symbols.
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DH] libavutil/mem_internal.h