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• Matplotlib animation error : Requested MovieWriter (ffmpeg) not available, while ffmpeg is installed

  3 juillet 2020, par Vivien Bonnot

  I'm trying to animate colormapping representations of parametric complex fonctions using Python.
I gradually put some things together, and checked that they worked properly. But I can't get the animation to be saved.

  


  I encountered this error :

  


  Requested MovieWriter (ffmpeg) not available

  


  However, ffmpeg is indeed installed on my system,
on Windows console ffmpeg -version returns all sorts of informations about ffmpeg. Additionnaly, I also installed ffmpeg in Python scripts directory using pip pip install ffmpeg, which was successfull. I also set up ffmepg path in my code : plt.rcParams['animation.ffmpeg_path'] = "C:\FFmpeg\bin\ffmpeg.exe"

  


  I'm runing out of ideas.

  


  Here is my code.
Thank you for reading.

  


  import numpy as np
import math
import matplotlib
import matplotlib.pyplot as plt
import matplotlib.animation as animation
pi=math.pi
plt.rcParams['animation.ffmpeg_path'] = "C:\FFmpeg\bin\ffmpeg.exe"
fig = plt.figure()

def complex_array_to_rgb(X, theme='dark', rmax=None):
  absmax = rmax or np.abs(X).max()
  Y = np.zeros(X.shape + (3,), dtype='float')
  Y[..., 0] = np.angle(X) / (2 * pi) % 1
  if theme == 'light':
    Y[..., 1] = np.clip(np.abs(X) / absmax, 0, 1)
    Y[..., 2] = 1
  elif theme == 'dark':
    Y[..., 1] = 1
    Y[..., 2] = np.clip(np.abs(X) / absmax, 0, 1)
  Y = matplotlib.colors.hsv_to_rgb(Y)
  return Y

# Set up formatting for the movie files
Writer = animation.writers['ffmpeg']
writer = Writer(fps=15, metadata=dict(artist='Me'), bitrate=1800)

fps = 10
nSeconds = 1
snapshots = [ complex_array_to_rgb(np.array([[3*(x + 1j*y)**(2.9+p/300) + 1/(x + 1j*y)**2 for x in np.arange(-1,1,0.05)] for y in np.arange(-1,1,0.05)])) for p in range( nSeconds * fps ) ]

fig = plt.figure( figsize=(3,3) )

Z2=snapshots[0]
im=plt.imshow(Z2, extent=(-1,1,-1,1))

def animate_func(i):
    if i % fps == 0:
        print( '.')

    im.set_array(snapshots[i])
    return [im]
    
anim = animation.FuncAnimation(
                               fig, 
                               animate_func, 
                               frames = nSeconds * fps,
                               interval = 1000 / fps, # in ms
                               )

anim.save('test_anim.mp4', writer=writer)


  


• FFMPEG Creates blurry video

  15 juillet 2020, par Nina

  With this library https://github.com/tanersener/mobile-ffmpeg, I am using FFMPEG on iOS. I am trying to create a video from audio, with its relevant waveform, background and a logo image added.

  


  let command = "-i \(audioPath) -i \(imagePath) -filter_complex \"[0:a]showwaves=s=hd720:mode=line: colors=0x666666|0x555555[v];[1:v]scale=hd720[bg];[bg][v]overlay=shortest=0:main_h-overlay_h-35[outv]\" -shortest -map '[outv]' -map 'a' -c:a aac -f mp4 \(videoPath)"


  


  With the above command, I am creating a video that has the audio, waveform and a background image.

  


  let artworkCommand = "-y -i \(videoPath) -i \(artworkPath) -filter_complex \"[1:v][0:v]scale2ref=200:200[logo1][base];[base][logo1]overlay=20:20[v]\" -map \"[v]\" -map 0:a -y -codec:a copy \(artVideoPath)"


  


  With the second command, I am adding a logo image on top-left corner.

  


  When I execute these commands directly on terminal, the output video is of high quality and has no issues. But when I try the same commands on iOS device, after the first second of the video, it becomes blurry.

  


  It looks like it is becoming blurry this way when I execute the first command itself. Can anyone point some light on why this is happening ? TIA.

  


  Update 1
Log - https://www.dropbox.com/s/ev8gw8bvfe1m7ur/Logs_FFMPEG.rtf?dl=0

  


  Update 2
I modified both the commands to include the bitrate, as suggested. It has improved the video, but still now and then it blurs out.

  


  let command = "-i \(audioPath) -i \(imagePath) -filter_complex \"[0:a]showwaves=s=hd720:mode=line: colors=0x666666|0x555555[v];[1:v]scale=hd720[bg];[bg][v]overlay=shortest=0:main_h-overlay_h-35[outv]\" -shortest -map '[outv]' -map 'a' -c:a aac -b:v 2M \(videoPath)"
let artworkCommand = "-y -i \(videoPath) -i \(artworkPath) -filter_complex \"[1:v][0:v]scale2ref=200:200[logo1][base];[base][logo1]overlay=20:20[v]\" -map \"[v]\" -map 'a' -c:a aac -b:v 2M \(artVideoPath)"


  


  Demo for both commands executed on iOS device - https://www.dropbox.com/s/6ux4obufb0eiax6/video1x1_art.MP4?dl=0

  


  Logs - https://www.dropbox.com/s/cjm259oehd048xb/Logs2.rtf?dl=0

  


• How to have the camera 'desynchronized' with Illumination changes ?

  30 juillet 2020, par vasudha

  For my current project, I have to record a video stream from a USB camera connected to Raspberry-Pi. While recording the videos if there are any illumination changes the camera should not synchronize it's preview/recording to the light change. Instead it should only record what it sees without any changes from camera input(for ex : exposure, contrast or brightness).

  


  


  1. I tried making changes in FFMPEG config and reinstalled it but it doesn't seem to work.

     


  


  2. I turned off auto_exposure with opencv but that wasn't useful either.

     


  


  


  I am using OpenCV for recording the videos later from which face recognition and skin-type classification will be done. So it is important that the Face color is not altered by the camera automatically with external illumination change. Can someone please help me with this ? Thanks.