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• Stream RAW8 video from camera using openCV and Python [Windows]

  14 novembre 2022, par awin

  We have a camera that streams RAW8 video at 1920x1080. The GUID used is GREY. We are able to stream video from this camera using ffmpeg on Windows with the below command :

  


  ffmpeg -f dshow -pix_fmt gray -video_size 1920x1080 -i video="CAM0" -f nut - | ffplay -


  


  We are now trying to grab images from this camera using OpenCV using the below code snippet, but its unable to grab any frame (frame_grabbed is always false)

  


  import cv2
import numpy as np

# reading the video from CAM0
source = cv2.VideoCapture(1)

height = 1920
width = 1080

source.set(cv2.CAP_PROP_FRAME_WIDTH, width)
source.set(cv2.CAP_PROP_FRAME_HEIGHT, height)


image = np.zeros([height, width, 3], np.uint8)

while True:
    # Extracting the frames
    frame_grabbed , image = source.read()

    if (frame_grabbed ):
        colour1 = cv2.cvtColor(image, cv2.COLOR_BayerRG2BGR)
        cv2.imshow("Demosaiced image", colour1)
    else:
        print("No images grabbed")

#Exit on q
    key = cv2.waitKey(1)
    if key == ord("q"):
       break

# closing the window
cv2.destroyAllWindows()
source.release()



  


  Are we missing something here ?

  


  We then came across this post to pipe ffmpeg output to python (link). However, when we are passing the command as below :

  


  command = [ 'ffmpeg.exe',
            '-f', 'dshow',
            '-i', 'video="CAM0"',
            '-pix_fmt', 'gray',
            '-video_size','1920x1080'
            '-f', 'nut', '-']


  


  its throwing

  


  


  Could not find video device with name ["CAM0"] among source devices
of type video. video="CAM0" : I/O error

  


  


  I have verified that the camera is present using the below command :

  


  command = [ 'ffmpeg.exe',
            '-list_devices', 'true',
            '-f', 'dshow',
            '-i', 'dummy']


  


  This detects CAM0 as shown below :

  


  ffmpeg version 5.0.1-full_build-www.gyan.dev Copyright (c) 2000-2022 the FFmpeg developers
  built with gcc 11.2.0 (Rev7, Built by MSYS2 project)
  configuration: --enable-gpl --enable-version3 --enable-static --disable-w32threads --disable-autodetect --enable-fontconfig --enable-iconv --enable-gnutls --enable-libxml2 --enable-gmp --enable-bzlib --enable-lzma --enable-libsnappy --enable-zlib --enable-librist --enable-libsrt --enable-libssh --enable-libzmq --enable-avisynth --enable-libbluray --enable-libcaca --enable-sdl2 --enable-libdav1d --enable-libdavs2 --enable-libuavs3d --enable-libzvbi --enable-librav1e --enable-libsvtav1 --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs2 --enable-libxvid --enable-libaom --enable-libopenjpeg --enable-libvpx --enable-mediafoundation --enable-libass --enable-frei0r --enable-libfreetype --enable-libfribidi --enable-liblensfun --enable-libvidstab 
--enable-libvmaf --enable-libzimg --enable-amf --enable-cuda-llvm --enable-cuvid --enable-ffnvcodec --enable-nvdec --enable-nvenc --enable-d3d11va --enable-dxva2 --enable-libmfx --enable-libshaderc --enable-vulkan --enable-libplacebo --enable-opencl --enable-libcdio --enable-libgme --enable-libmodplug --enable-libopenmpt --enable-libopencore-amrwb --enable-libmp3lame --enable-libshine --enable-libtheora --enable-libtwolame --enable-libvo-amrwbenc --enable-libilbc --enable-libgsm --enable-libopencore-amrnb --enable-libopus --enable-libspeex --enable-libvorbis --enable-ladspa --enable-libbs2b --enable-libflite --enable-libmysofa --enable-librubberband --enable-libsoxr --enable-chromaprint
  libavutil      57. 17.100 / 57. 17.100
  libavcodec     59. 18.100 / 59. 18.100
  libavformat    59. 16.100 / 59. 16.100
  libavdevice    59.  4.100 / 59.  4.100
  libavfilter     8. 24.100 /  8. 24.100
  libswscale      6.  4.100 /  6.  4.100
  libswresample   4.  3.100 /  4.  3.100
  libpostproc    56.  3.100 / 56.  3.100
[dshow @ 000001ea39e40600] "HP HD Camera" (video)
[dshow @ 000001ea39e40600]   Alternative name "@device_pnp_\\?\usb#vid_04f2&pid_b6bf&mi_00#6&1737142c&0&0000#{65e8773d-8f56-11d0-a3b9-00a0c9223196}\global"
[dshow @ 000001ea39e40600] "CAM0" (video)
[dshow @ 000001ea39e40600]   Alternative name "@device_pnp_\\?\usb#vid_0400&pid_0011&mi_00#7&1affbd5b&0&0000#{65e8773d-8f56-11d0-a3b9-00a0c9223196}\global"


  


  In short, we are able to capture video using ffmpeg commandline, but unable to grab any frame using OpenCV videocapture or ffmpeg in opencv. Any pointers ?

  


  Thanks !

  


• Combining png and mp3, why using -loop 1 on image and -shortest tag doesn't cut the output length when audio ends ?

  9 novembre 2022, par Alexander

  I have several image and audio files and I want to combine each of the set to a separate video file where image is stretched to audio file length. For example a lion image should be displayed as long as the lion voice is being played. The output file should end when lion audio ends.

  


  I also try to normalize output clips resolution since image files doesn't have same width/height.

  


  Here is the command I'm currently running. Command is on one line but I made some line breaks here for your convenience.

  


  -loop 1 
-i "C:\Temp\screenshot\clip_1.png"
-i "C:\Temp\audio\clip_1.mp3" 
-shortest 
-filter_complex "[0:v]scale=3000:-2:force_original_aspect_ratio=decrease" 
-c:v h264_nvenc 
-c:a aac 
-b:a 192k 
-y 
C:\Temp\clips\clip_1.mp4


  


  To my understanding the -loop 1 before image input should make it to loop infinite and -shortest should end the video when shortest input (audio in this case) ends. In following example, the audio file is 6 seconds long but the output is always 20 seconds.

  


  Here is the full output of ffmpeg :

  


  ffmpeg version 2022-11-03-git-5ccd4d3060-full_build-www.gyan.dev Copyright (c) 2000-2022 the FFmpeg developers
  built with gcc 12.1.0 (Rev2, Built by MSYS2 project)
  configuration: --enable-gpl --enable-version3 --enable-static --disable-w32threads --disable-autodetect --enable-fontconfig --enable-iconv --enable-gnutls --enable-libxml2 --enable-gmp --enable-bzlib --enable-lzma --enable-libsnappy --enable-zlib --enable-librist --enable-libsrt --enable-libssh --enable-libzmq --enable-avisynth --enable-libbluray --enable-libcaca --enable-sdl2 --enable-libaribb24 --enable-libdav1d --enable-libdavs2 --enabl
e-libuavs3d --enable-libzvbi --enable-librav1e --enable-libsvtav1 --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs2 --enable-libxvid --enable-libaom --enable-libjxl --enable-libopenjpeg --enable-libvpx --enable-mediafoundation --enable-libass --enable-frei0r --enable-libfreetype --enable-libfribidi --enable-liblensfun --enable-libvidstab --enable-libvmaf --enable-libzimg --enable-amf --enable-cuda-llvm --enable-cuvid --ena
ble-ffnvcodec --enable-nvdec --enable-nvenc --enable-d3d11va --enable-dxva2 --enable-libvpl --enable-libshaderc --enable-vulkan --enable-libplacebo --enable-opencl --enable-libcdio --enable-libgme --enable-libmodplug --enable-libopenmpt --enable-libopencore-amrwb --enable-libmp3lame --enable-libshine --enable-libtheora --enable-libtwolame --enable-libvo-amrwbenc --enable-libilbc --enable-libgsm --enable-libopencore-amrnb --enable-libopus --e
nable-libspeex --enable-libvorbis --enable-ladspa --enable-libbs2b --enable-libflite --enable-libmysofa --enable-librubberband --enable-libsoxr --enable-chromaprint
  libavutil      57. 40.100 / 57. 40.100
  libavcodec     59. 51.101 / 59. 51.101
  libavformat    59. 34.101 / 59. 34.101
  libavdevice    59.  8.101 / 59.  8.101
  libavfilter     8. 49.101 /  8. 49.101
  libswscale      6.  8.112 /  6.  8.112
  libswresample   4.  9.100 /  4.  9.100
  libpostproc    56.  7.100 / 56.  7.100
Input #0, png_pipe, from 'C:\Temp\screenshot\clip_1.png':
  Duration: N/A, bitrate: N/A
  Stream #0:0: Video: png, rgba(pc), 640x148, 25 fps, 25 tbr, 25 tbn
[mp3 @ 0000016c26784a80] Estimating duration from bitrate, this may be inaccurate
Input #1, mp3, from 'C:\Temp\audio\clip_1.mp3':
  Duration: 00:00:06.10, start: 0.000000, bitrate: 32 kb/s
  Stream #1:0: Audio: mp3, 24000 Hz, mono, fltp, 32 kb/s
Stream mapping:
  Stream #0:0 (png) -> scale:default (graph 0)
  scale:default (graph 0) -> Stream #0:0 (h264_nvenc)
  Stream #1:0 -> #0:1 (mp3 (mp3float) -> aac (native))
Press [q] to stop, [?] for help
[aac @ 0000016c267ab180] Too many bits 8192.000000 > 6144 per frame requested, clamping to max
Output #0, mp4, to 'C:\Temp\clips\clip_1.mp4':
  Metadata:
    encoder         : Lavf59.34.101
  Stream #0:0: Video: h264 (Main) (avc1 / 0x31637661), rgba(pc, gbr/unknown/unknown, progressive), 3000x694, q=2-31, 2000 kb/s, 25 fps, 12800 tbn
    Metadata:
      encoder         : Lavc59.51.101 h264_nvenc
    Side data:
      cpb: bitrate max/min/avg: 0/0/2000000 buffer size: 4000000 vbv_delay: N/A
  Stream #0:1: Audio: aac (LC) (mp4a / 0x6134706D), 24000 Hz, mono, fltp, 144 kb/s
    Metadata:
      encoder         : Lavc59.51.101 aac
frame=  504 fps=149 q=11.0 Lsize=     925kB time=00:00:20.00 bitrate= 378.8kbits/s speed=5.91x
video:852kB audio:67kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.645776%
[aac @ 0000016c267ab180] Qavg: 65496.695


  


• ffmpeg connection timeout for rtsp streams

  24 décembre 2022, par Bods1994

  i tried to recoreds rtsp streams using ffmpeg with this command :
ffmpeg -hide_banner -loglevel error -y -rtsp_transport tcp -i rtsp://192.168.0.147:554/live/ch0 -t 600 -acodec copy -vcodec copy -metadata title="CAM1" -timeout 3 -f segment -reset_timestamps 1 -segment_time 60 -segment_atclocktime 1 -segment_format mkv -strftime 1 C:\temp\%Y%m%d_%H%M%S.mkv

  


  If the connection is lost during recording, ffmpeg will exit within severals milliseconds.
But if the camera ist not available when connecting, it will hang forever.

  


  I read severals posts to use "-stimeout Unrecognized option 'stimeout'. Error splitting the argument list : Option not found

  


  For my tests i used the windows version downloaded from the two mirrors listed at https://ffmpeg.org/download.html#build-windows.
Each buils ist from 2022-12-22.

  


  Has someone an idea how to detect conection problems and to a retry after some seconds ?