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Video

Requirements#

Requires the image-dataset-converter-video library.

Plugins#

Extract frames from video file#

The following extracts a total of 100 frames from ./input/video.mp4, using every 20th frame and stores the images in the ./output directory: 

idc-convert \
  -l INFO \
  from-video-file \
    -l INFO \
    -i ./input/video.mp4 \
    -t od \
    -n 20 \
    -m 100 \
  to-data \
    -l INFO \
    -o ./output/

Though the data type is object detection (-t od), this is not really relevant in this example. If there were other filters, e.g., for applying object detection Redis models, then it would be necessary to specify the correct type.

Capture frames from a webcam (individual JPG files)#

The following captures a total of 10 images from a webcam (using every 20th frame) and stores them as individual JPG files in the ./output directory:

idc-convert \
  -l INFO \
  from-webcam \
    -l INFO \
    -i 0 \
    -t od \
    -n 20 \
    -m 10 \
  to-data \
    -l INFO \
    -o ./output

Capture frames from a webcam (store as MJPEG file)#

The following captures a total of 100 images from a webcam (using every 10th frame) and generates a MJPEG file, which can be viewed with, e.g., ffplay:

idc-convert \
  -l INFO \
  from-webcam \
    -l INFO \
    -i 0 \
    -t od \
    -n 10 \
    -m 100 \
  to-video-file \
    -l INFO \
    -o ./output/webcam.mjpeg

Calculating differences between frames#

Depending on the scene, frames may not differ much between each other, making it hard to extract frames by using specific intervals. The calc-frame-changes writer computes differences between frames and output a histogram of these differences. Using the min/max of the bins of the histogram, it is possible to find a suitable change threshold. This threshold can be utilized by the skip-similar-frames filter to discard too similar frames, whittling down the number of extracted frames automatically. The histogram can be output in textual form, CSV or JSON; either on stdout or stored in a file.

idc-convert \
  -l INFO \
  from-video-file \
    -l INFO \
    -i ./input/video.mp4 \
    -t od \
    -n 10 \
    -m 2000 \
  calc-frame-changes \
    -f text

Skipping similar frames#

The following command keeps frames that differ enough from each other and discards all others, using the skip-similar-frames filter. The threshold applied by the filter was previously determined by the calc-frame-changes filter.

idc-convert \
  -l INFO \
  from-video-file \
    -l INFO \
    -i ./input/video.mp4 \
    -t od \
  skip-similar-frames \
    -t 0.005 \
  to-data \
    -l INFO \
    -o ./output

Youtube video#

The from-youtube reader allows you to grab frames from a Youtube video:

idc-convert \
  -l INFO \
  from-youtube \
    -l INFO \
    -i "https://www.youtube.com/watch?v=CFdZWgiAj8I" \
    -p the_cloud-kitty_flanagan- \
    -t od \
    -n 20 \
    -m 10 \
  to-data \
    -l INFO \
    -o ./output

NB: Please make sure not to infringe on any copyright.

Youtube live stream#

The from-youtube-live reader allows you to grab frames from a Youtube live stream, e.g., wildlife cameras:

idc-convert \
  -l INFO \
  from-youtube-live \
    -l INFO \
    -i "https://www.youtube.com/watch?v=2swy9gysvOY" \
    -p african_river_wildlife_camera- \
    -t od \
    -n 20 \
    -m 10 \
  to-data \
    -l INFO \
    -o ./output

NB: Please make sure not to infringe on any copyright.