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• How to record a 5 second video on Raspberry Pi 3 with USB webcam ?

  16 mars 2023, par Feengineer

  Hi i tried to record a video whit a USB-webcam on my RaspberryPi.
When i type ffplay /dev/video0 I do see a live video, but when i try to record it with ffmpeg the video output is like a black screen with like the traffic cone in my VLC media player. I tried saving the video as a .mkv and .mp4 file. Anyone know how to fix this ?

  


  The code i used to record a video is : ffmpeg -f v4l2 -t 5 -framerate 25 -video_size 640x480 -i /dev/video0 output.mkv and ffmpeg -f v4l2 -t 5 -framerate 25 -video_size 640x480 -i /dev/video0 output.mp4
The video did show up in the folder, but it doesn't show video when opening.

  


  edit : I fixed it now by changing the file type to .avi, but if anyone can still explain how to get .mkv or .mp4, let me know :)

  


• Feeding a series of images to ffmpeg as each image is created [closed]

  5 février 2013, par Mark Schneider

  I'm trying to use ffmpeg to build a 1280x720 slide-show from a sequence of pictures and videos, but I have concerns about potential disk I/O bottleneck.

  I expect a typical slide-show to have about 50 pictures and 2-3 videos (10-15 seconds each at 30 fps). I would like to show each picture for 3-4 seconds (possibly with a
  Ken Burns effect) with a smooth 2 second crossfade between each set of pictures (or for pictures adjacent to videos - between the picture and the first/last frame of the video).

  Given about 50 pictures, the crossfades alone would amount to about 3,000 images (50 transitions x 2 secs/transition x 30 fps). And I suppose if I implement a Ken Burns effect during each picture's 3-4 second showing, I'd have to provide ffmpeg with individual images for each of those frames. (I'm writing a script in Ruby that will pull a list of images from a database and in turn call ImageMagick to create the individual images for each frame. As I understand it, the RMagick library interfaces with ImageMagick such that the output images come back as in-memory objects without needing to write to disk. FWIW, I'm developing in Windows 8 and will deploy to Heroku.)

  All of the slideshow examples I've found online feed ffmpeg a set of images which have already been created. However, in an effort to avoid waiting on considerable disk I/O, I'd like to feed each image to ffmpeg as the image is created rather than create them all in advance.

  Is there a way to send each image file to ffmpeg on the fly as the file is created in memory ?

• how to put image files from one folder to make a video in python

  23 septembre 2015, par Gaurav16

  I have written a code to collect all image files from one folder, so that I can make a video out of it.

  But while compiling I getting an error saying "Error creating movie, return code: 4 Try running with --verbose-debug"

    #import numpy as np
  
  import matplotlib.pyplot as plt
  
  import matplotlib.animation as animation
  
  import glob, os
  
  from PIL import Image
  
  fig = plt.figure()
  
  #size = 128, 128
  
  ims=[]
  
  #print(len(ims))
  
  #im=Image.open(ims[5])
  
  #im.show()
  
  for infile in glob.glob("*.png"):
  
      file, ext = os.path.splitext(infile)
  
      im = Image.open(infile)
  
      im1=plt.imshow(im)
  
      ims.append([im1])
  
  print(len(ims))    
  
  ani = animation.ArtistAnimation(fig, ims)
  
  ani.save('MovWave.mpeg', writer="ffmpeg")
  
  plt.show()