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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 !

  


• How to convert mkv to mp4 in ffmpeg losslessly

  16 novembre 2022, par crsswrdz

  I'm trying to losslessly convert an .mkv to .mp4.
(For use in Premiere Pro for film analysis and teaching).

  


  When I do so, I get a noticeable drop in file size (11gb to 2gb) and image quality.
The 5.1 streams are maintained but lose their mapping (everything seems displaced i.e. center channel now in the right channel) and the subtitles are lost.

  


  Is it possible to losslessly remux this .mkv to .mp4 ?
I don't want to re-encode it.

  


  E:\>ffmpeg -i Dune.mkv Dune.mp4
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 --enable-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 --enable-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 --enable-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, matroska,webm, from 'Dune.mkv':
  Metadata:
    title           : Dune
    encoder         : libebml v1.4.2 + libmatroska v1.6.4
    creation_time   : 2021-10-17T11:10:41.000000Z
  Duration: 02:28:56.16, start: 0.000000, bitrate: 10192 kb/s
  Stream #0:0(eng): Video: h264 (High), yuv420p(tv, bt709, progressive), 1920x776, SAR 1:1 DAR 240:97, 25 fps, 25 tbr, 1k tbn (default)
    Metadata:
      BPS             : 9806853
      DURATION        : 02:28:56.160000000
      NUMBER_OF_FRAMES: 223404
      NUMBER_OF_BYTES : 10954451639
      _STATISTICS_WRITING_APP: mkvmerge v62.0.0.1 ('Apollo') 64-bit
      _STATISTICS_WRITING_DATE_UTC: 2021-10-17 11:10:41
      _STATISTICS_TAGS: BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES
  Stream #0:1(eng): Audio: ac3, 48000 Hz, 5.1(side), fltp, 384 kb/s (default)
    Metadata:
      BPS             : 384000
      DURATION        : 02:28:56.128000000
      NUMBER_OF_FRAMES: 279254
      NUMBER_OF_BYTES : 428934144
      _STATISTICS_WRITING_APP: mkvmerge v62.0.0.1 ('Apollo') 64-bit
      _STATISTICS_WRITING_DATE_UTC: 2021-10-17 11:10:41
      _STATISTICS_TAGS: BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES
  Stream #0:2(eng): Subtitle: subrip (forced)
    Metadata:
      title           : FORCED
      BPS             : 1
      DURATION        : 01:49:04.860000000
      NUMBER_OF_FRAMES: 43
      NUMBER_OF_BYTES : 1104
      _STATISTICS_WRITING_APP: mkvmerge v62.0.0.1 ('Apollo') 64-bit
      _STATISTICS_WRITING_DATE_UTC: 2021-10-17 11:10:41
      _STATISTICS_TAGS: BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES
  Stream #0:3(eng): Subtitle: subrip (default)
    Metadata:
      BPS             : 34
      DURATION        : 02:20:49.064000000
      NUMBER_OF_FRAMES: 998
      NUMBER_OF_BYTES : 36676
      _STATISTICS_WRITING_APP: mkvmerge v62.0.0.1 ('Apollo') 64-bit
      _STATISTICS_WRITING_DATE_UTC: 2021-10-17 11:10:41
      _STATISTICS_TAGS: BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES
Stream mapping:
  Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264))
  Stream #0:1 -> #0:1 (ac3 (native) -> aac (native))
Press [q] to stop, [?] for help
[aac @ 0000016e39c4a7c0] Using a PCE to encode channel layout "5.1(side)"
[libx264 @ 0000016e396ded40] using SAR=1/1
[libx264 @ 0000016e396ded40] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2
[libx264 @ 0000016e396ded40] profile High, level 4.0, 4:2:0, 8-bit
[libx264 @ 0000016e396ded40] 264 - core 164 r3101 b093bbe - H.264/MPEG-4 AVC codec - Copyleft 2003-2022 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=24 lookahead_threads=4 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
Output #0, mp4, to 'Dune.mp4':
  Metadata:
    title           : Dune
    encoder         : Lavf59.34.101
  Stream #0:0(eng): Video: h264 (avc1 / 0x31637661), yuv420p(tv, bt709, progressive), 1920x776 [SAR 1:1 DAR 240:97], q=2-31, 25 fps, 12800 tbn (default)
    Metadata:
      BPS             : 9806853
      DURATION        : 02:28:56.160000000
      NUMBER_OF_FRAMES: 223404
      NUMBER_OF_BYTES : 10954451639
      _STATISTICS_WRITING_APP: mkvmerge v62.0.0.1 ('Apollo') 64-bit
      _STATISTICS_WRITING_DATE_UTC: 2021-10-17 11:10:41
      _STATISTICS_TAGS: BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES
      encoder         : Lavc59.51.101 libx264
    Side data:
      cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: N/A
  Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, 5.1(side), fltp, 394 kb/s (default)
    Metadata:
      BPS             : 384000
      DURATION        : 02:28:56.128000000
      NUMBER_OF_FRAMES: 279254
      NUMBER_OF_BYTES : 428934144
      _STATISTICS_WRITING_APP: mkvmerge v62.0.0.1 ('Apollo') 64-bit
      _STATISTICS_WRITING_DATE_UTC: 2021-10-17 11:10:41
      _STATISTICS_TAGS: BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES
      encoder         : Lavc59.51.101 aac
frame=115222 fps=216 q=28.0 00000000000000000000000004009000size= 1180416kB time=01:16:52.41 bitrate=2096.5kbits/s speed=8.65x



  


• How to overlay sequence of frames on video using ffmpeg-python ?

  19 novembre 2022, par Yogesh Yadav

  I tried below but it is only showing the background video.

  


  background_video = ffmpeg.input( "input.mp4")
overlay_video = ffmpeg.input(f'{frames_folder}*.png', pattern_type='glob', framerate=25)
subprocess = ffmpeg.overlay(
                          background_video,
                          overlay_video,
                        ).filter("setsar", sar=1)


  


  I also tried to assemble sequence of frames into .webm/.mov video but transparency is lost. video is taking black as background.

  


  P.s - frame size is same as background video size. So no scaling needed.

  


  Edit

  


  I tried @Rotem suggestions

  


  


  Try using single PNG image first

  


  


  overlay_video =  ffmpeg.input('test-frame.png')


  


  It's not working for frames generated by OpenCV but working for any other png image. This is weird, when I'm manually viewing these frames folder it's showing blank images(Link to my frames folder).
But If I convert these frames into the video(see below) it is showing correctly what I draw on each frame.

  


  output_options = {
                    'crf': 20,
                    'preset': 'slower',
                    'movflags': 'faststart',
                    'pix_fmt': 'yuv420p'
                }
ffmpeg.input(f'{frames_folder}*.png', pattern_type='glob', framerate=25 , reinit_filter=0).output(
                    'movie.avi',
                    **output_options
                ).global_args('-report').run()


  


  


  try creating a video from all the PNG images without overlay

  


  


  It's working as expected only issue is transparency. Is there is way to create a transparent background video ? I tried .webm/.mov/.avi but no luck.

  


  


  Add .global_args('-report') and check the log file

  


  


  Report written to "ffmpeg-20221119-110731.log"
Log level: 48
ffmpeg version 5.1 Copyright (c) 2000-2022 the FFmpeg developers
  built with Apple clang version 13.1.6 (clang-1316.0.21.2.5)
  configuration: --prefix=/opt/homebrew/Cellar/ffmpeg/5.1 --enable-shared --enable-pthreads --enable-version3 --cc=clang --host-cflags= --host-ldflags= --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libbluray --enable-libdav1d --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librist --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libspeex --enable-libsoxr --enable-libzmq --enable-libzimg --disable-libjack --disable-indev=jack --enable-videotoolbox --enable-neon
  libavutil      57. 28.100 / 57. 28.100
  libavcodec     59. 37.100 / 59. 37.100
  libavformat    59. 27.100 / 59. 27.100
  libavdevice    59.  7.100 / 59.  7.100
  libavfilter     8. 44.100 /  8. 44.100
  libswscale      6.  7.100 /  6.  7.100
  libswresample   4.  7.100 /  4.  7.100
  libpostproc    56.  6.100 / 56.  6.100
Input #0, image2, from './frames/*.png':
  Duration: 00:00:05.00, start: 0.000000, bitrate: N/A
  Stream #0:0: Video: png, rgba(pc), 1920x1080, 25 fps, 25 tbr, 25 tbn
Codec AVOption crf (Select the quality for constant quality mode) specified for output file #0 (movie.avi) has not been used for any stream. The most likely reason is either wrong type (e.g. a video option with no video streams) or that it is a private option of some encoder which was not actually used for any stream.
Codec AVOption preset (Configuration preset) specified for output file #0 (movie.avi) has not been used for any stream. The most likely reason is either wrong type (e.g. a video option with no video streams) or that it is a private option of some encoder which was not actually used for any stream.
Stream mapping:
  Stream #0:0 -> #0:0 (png (native) -> mpeg4 (native))
Press [q] to stop, [?] for help
Output #0, avi, to 'movie.avi':
  Metadata:
    ISFT            : Lavf59.27.100
  Stream #0:0: Video: mpeg4 (FMP4 / 0x34504D46), yuv420p(tv, progressive), 1920x1080, q=2-31, 200 kb/s, 25 fps, 25 tbn
    Metadata:
      encoder         : Lavc59.37.100 mpeg4
    Side data:
      cpb: bitrate max/min/avg: 0/0/200000 buffer size: 0 vbv_delay: N/A
frame=  125 fps= 85 q=31.0 Lsize=     491kB time=00:00:05.00 bitrate= 804.3kbits/s speed=3.39x    
video:482kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 1.772174%


  


  To draw frame I used below.

  


  for i in range(num_frames):
            transparent_img = np.zeros((height, width, 4),  dtype=np.uint8)
            cv2.line(transparent_img, (x1,y1), (x2,y2) ,(255, 255, 255), thickness=1, lineType=cv2.LINE_AA)
            self.frames.append(transparent_img)


## To Save each frame of the video in the given folder
for i, f in enumerate(frames):
    cv2.imwrite("{}/{:0{n}d}.png".format(path_to_frames, i, n=num_digits), f)