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• lavr : only save/restore the mixing matrix if mixing is being done

  30 novembre 2012, par Justin Ruggles

  lavr : only save/restore the mixing matrix if mixing is being done

• Opencv VideoCapture not streaming RTSP link and returns "no frame !"

  6 septembre 2023, par Asadullah Naeem

  I am trying to stream my HikVision IP camera throough python. I am using cv2.VideoCapture("rtsp_link") which works fine on my Laptop but when I try to run the same python script with same Opencv and FFmpeg version it gives me following error :

  


  Error :

  


  [h264 @ 000002124c7f9a40] missing picture in access unit with size 47
[h264 @ 000002124c7f9a40] no frame!


  


  I have so far tried to run this script on 5 computer devices but it gives the same error. I am using the following python script and my Opencv version is 4.6.0.66 and ffmpeg version 2022-06-20-git-56419428a8-essentials_build-www.gyan.dev :

  


  Python Script :

  


  import cv2

# RTSP stream URL
rtsp_url = "rtsp://username:password@ip_address:port/Streaming/Channels/501"

# Open the RTSP stream
cap = cv2.VideoCapture(rtsp_url)

# Check if the stream was successfully opened
if not cap.isOpened():
    print("Failed to open RTSP stream.")
    exit()

# Read and display frames from the stream
while True:
    # Read a frame from the stream
    ret, frame = cap.read()

    # Check if the frame was successfully read
    if not ret:
        print("Failed to read frame from RTSP stream.")
        break

    # Display the frame
    cv2.imshow("RTSP Stream", frame)

    # Exit if 'q' is pressed
    if cv2.waitKey(1) & 0xFF == ord('q'):
        break

# Release the resources
cap.release()
cv2.destroyAllWindows()



  


  Update :

  


  Code runs on a laptop on both wifi and mobile internet (4G) but on other devices rtsp link is accessible only with mobile internet (4G).

  


• ffmpeg configure always returns "not found" when using sysroot and cross-prefix options - how to use them correctly ?

  5 août 2014, par user2212461

  I try to build ffmpeg with a cross-compiler. When setting the configure flags I am getting the following errors :

  WARNING: Compiler does not indicate floating-point ABI, guessing soft.
  
  build_it.sh: 29: build_it.sh: --sysroot=/home/android/android-ndk-r9/platforms/
  
      android-9/arch-arm/: not found
  
  build_it.sh: 32: build_it.sh.sh: --cross-prefix=/home/android/android-ndk-r9/
  
      toolchains/arm-linux-androideabi-4.8/prebuilt/linux-x86/bin/arm-linux-and
  
      roideabi-: not found

  The error message "not found" sounds like the paths dont exist but they are all correct and existing. How can I resolve this error ?

  build_it.sh :

  NDK=/home/android/android-ndk-r9
  
  SYSROOT=$NDK/platforms/android-9/arch-arm/
  
  TOOLCHAIN=$NDK/toolchains/arm-linux-androideabi-4.8/prebuilt/linux-x86
  
  CPU=arm
  
  PREFIX=test
  
  ADDI_CFLAGS="-marm"
  
  platform="android-9"
  
  
  
  ./configure \
  
      --disable-asm \
  
      --enable-shared \
  
      --target-os=linux \
  
      --arch=arm \
  
      --enable-cross-compile \
  
      --disable-static \
  
      --sysroot=$SYSROOT \
  
      --extra-cflags="-Os -fpic $ADDI_CFLAGS" \
  
      --extra-ldflags="$ADDI_LDFLAGS"
  
      --cross-prefix=$TOOLCHAIN/bin/arm-linux-androideabi- \
  
      --prefix=$PREFIX \
  
  
  
  ##configure fails here
  
  ...