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• Using FFMPEG in OpenCV for reading frames from rtsp camera

  19 janvier 2023, par Paloma Jimeno

  I am writing a small script in python3.8 to read frames from a rtsp camera. The code is as follows :

  


  import cv2 
gst_out =  "rtsp://admin:psw@IP:88/videoMain"
cap = cv2.VideoCapture(gst_out, cv2.CAP_FFMPEG)

while(cap.isOpened()):
    ret, frame = cap.read()
    print("New Frame")
    cv2.imshow('frame', frame)
    if cv2.waitKey(20) & 0xFF == ord('q'):
        break
cap.release()
cv2.destroyAllWindows()


  


  However, cap is never opened and i do not understand why. I am using opencv 4.5.2 in ubuntu 20.04. This is what i get when i call cv2.getBuildInformation() :

  


   Video I/O:
    DC1394:                      NO
    FFMPEG:                      YES
      avcodec:                   YES (58.54.100)
      avformat:                  YES (58.29.100)
      avutil:                    YES (56.31.100)
      swscale:                   YES (5.5.100)
      avresample:                NO
    GStreamer:                   YES (1.16.2)
    v4l/v4l2:                    YES (linux/videodev2.h)



  


  So as you can see FFMPEG is available. In fact, when i execute ffmpeg in terminal, i get the following :

  


  ffmpeg version 4.2.7-0ubuntu0.1 Copyright (c) 2000-2022 the FFmpeg developers
  built with gcc 9 (Ubuntu 9.4.0-1ubuntu1~20.04.1)
  configuration: --prefix=/usr --extra-version=0ubuntu0.1 --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --arch=amd64 --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-nvenc --enable-chromaprint --enable-frei0r --enable-libx264 --enable-shared
  libavutil      56. 31.100 / 56. 31.100
  libavcodec     58. 54.100 / 58. 54.100
  libavformat    58. 29.100 / 58. 29.100
  libavdevice    58.  8.100 / 58.  8.100
  libavfilter     7. 57.100 /  7. 57.100
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  5.100 /  5.  5.100
  libswresample   3.  5.100 /  3.  5.100
  libpostproc    55.  5.100 / 55.  5.100
Hyper fast Audio and Video encoder
usage: ffmpeg [options] [[infile options] -i infile]... {[outfile options] outfile}...



  


  Could you tell me what could be wrong ? I have tested the IP in the browser and everything is working properly.

  


  Thank you

  


• Parsing SCTE-35 Data stream with FFMPEG

  7 avril 2023, par Alex Dube

  I'm trying to parse a data stream containing SCTE-35 info (or so I hope) coming from a .ts file obtained from a master .m3u8 playlist using FFMPEG.

  


  I'm using the following command to try and parse map the specific data stream to an outfile :

  


  ffmpeg -i https://stream-url/master/ts_file.ts -y -map 0:2 -c copy -copy_unknown -f data scte35data.bin


  


  My full error log as follows :

  


  ffmpeg version 5.1.2 Copyright (c) 2000-2022 the FFmpeg developers
  built with Apple clang version 14.0.0 (clang-1400.0.29.202)
  configuration: --prefix=/opt/homebrew/Cellar/ffmpeg/5.1.2_3 --enable-shared --enable-pthreads --enable-version3 --cc=clang --host-cflags= --host-ldflags= --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libaribb24 --enable-libbluray --enable-libdav1d --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librist --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libsvtav1 --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
[mpegts @ 0x155f04080] start time for stream 2 is not set in estimate_timings_from_pts
Input #0, mpegts, from 'https://rcavlive.akamaized.net/hls/live/704025/xcanrdi/20230320T065736/master_2000/00012/master_2000_01207.ts':
  Duration: 00:00:08.00, start: 10442.033333, bitrate: 2282 kb/s
  Program 1 
  Stream #0:0[0x1e1]: Video: h264 (High) ([27][0][0][0] / 0x001B), yuv420p(progressive), 852x480 [SAR 1:1 DAR 71:40], Closed Captions, 30 fps, 30 tbr, 90k tbn
  Stream #0:1[0x1e2](fre): Audio: aac (LC) ([15][0][0][0] / 0x000F), 48000 Hz, stereo, fltp, 127 kb/s
  Stream #0:2[0x1f4]: Data: scte_35
  Stream #0:3[0x1f6]: Data: timed_id3 (ID3  / 0x20334449)
Output #0, data, to 'RecordingScripts/Tests/1.bin':
  Metadata:
    encoder         : Lavf59.27.100
  Stream #0:0: Data: scte_35
Stream mapping:
  Stream #0:2 -> #0:0 (copy)
Press [q] to stop, [?] for help
size=       0kB time=00:00:00.00 bitrate=N/A speed=   0x    
video:0kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown
Output file is empty, nothing was encoded (check -ss / -t / -frames parameters if used)


  


• Checking if a video has a sound even if it has an audio codec ?

  19 janvier 2023, par Sreenivasan

  I am new to intermediate python and I am trying to find if a downloaded video has sound, every video I download has an audio codec but I want to get the decibel of sound that audio has in that particular video.

  


  For example, this 'FFmpeg' command line script allows me to get the full info :

  


  ffmpeg -hide_banner -i testvideo.mp4 -af volumedetect -vn -f null - 2>&1


  


  this yields the below result in my command prompt(windows user here with win 11)

  


  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'testvideo.mp4':

Metadata:

major_brand : mp42

minor_version : 0

compatible_brands: mp42mp41isomavc1

creation_time : 2022-04-12T23:21:45.000000Z

Duration: 00:00:40.58, start: 0.000000, bitrate: 4104 kb/s

Stream #0:0[0x1](und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709, progressive), 1920x1080, 3846 kb/s, 29.97 fps, 29.97 tbr, 30k tbn (default)

Metadata:

creation_time : 2022-04-12T23:21:45.000000Z

handler_name : L-SMASH Video Handler

vendor_id : [0][0][0][0]

encoder : AVC Coding

Stream #0:1[0x2](und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 253 kb/s (default)

Metadata:

creation_time : 2022-04-12T23:21:45.000000Z

handler_name : L-SMASH Audio Handler

vendor_id : [0][0][0][0]

Stream mapping:

Stream #0:1 -> #0:0 (aac (native) -> pcm_s16le (native))

Press [q] to stop, [?] for help

Output #0, null, to 'pipe:':

Metadata:

major_brand : mp42

minor_version : 0

compatible_brands: mp42mp41isomavc1

encoder : Lavf59.35.100

Stream #0:0(und): Audio: pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s (default)

Metadata:

creation_time : 2022-04-12T23:21:45.000000Z

handler_name : L-SMASH Audio Handler

vendor_id : [0][0][0][0]

encoder : Lavc59.56.100 pcm_s16le

size=N/A time=00:00:40.55 bitrate=N/A speed=1.22e+03x

video:0kB audio:7608kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown

[Parsed_volumedetect_0 @ 0000026609be08c0] n_samples: 3895296

[Parsed_volumedetect_0 @ 0000026609be08c0] mean_volume: -91.0 dB

[Parsed_volumedetect_0 @ 0000026609be08c0] max_volume: -91.0 dB

[Parsed_volumedetect_0 @ 0000026609be08c0] histogram_91db: 3895296


  


  As you can see there are 'parsed_volumedetect' values with dB which has a mean value of -91 dB which means the audio has no sound, i.e., the video has audio but there is no sound.

  


  Now I am trying to do the same in python and I want to get just the mean volume value to be stored in a variable so that I can check if the video has any sound in it.

  


  I have seen the subprocess codes so far but when I try to run my code in VS-Code - python 3.11 :

  


  import subprocess    
result = subprocess.run(["ffmpeg", "-hide_banner", "-af", "volumedetect", "-vn", "-f", "null", "testvideo1.mp4"],
    stdout=subprocess.PIPE,
    stderr=subprocess.STDOUT,
    shell=True)
    print(result.stdout)


  


  It says that :

  


  PS C:\Users\balaj\OneDrive\Documents\Programming language\python files> c:; cd 'c:\Users\balaj\OneDrive\Documents\Programming language\python files'; & 'C:\Python311\python.exe' 'c:\Users\balaj\.vscode\extensions\ms-python.python-2022.20.2\pythonFiles\lib\python\debugpy\adapter/../..\debugpy\launcher' '51760' '--' 'c:\Users\balaj\OneDrive\Documents\Programming language\python files\devproject\sample.py'

b"Output #0, null, to 'testvideo1.mp4':\r\nOutput file #0 does not contain any stream\r\n"


  


  Any help is much appreciated. Sorry for the long post... TIA !!!

  


  Just a quick update :
The result is the same for video files that have sound(I tested in VLC) and don't have sound.

  


  Another update :
I have changed the subprocess.runcode to the exact same as I called in the cmd windows :

  


  result = subprocess.run(["ffmpeg", "-hide_banner","-i","testvideo-sound.mp4", "-af", "volumedetect", "-vn", "-f", "null", "-2>&1"]


  


  Now the result is this :

  


  b'The handle could not be duplicated\r\nduring redirection of handle 1.\r\n'