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• OpenCV Encoding to H264 changing original RGB pixel values for gray images

  13 janvier 2020, par CristoJV

  I have the following issue :
  I’m creating a uniform gray color video (for testing) using OpenCV VideoWriter. The output video will reproduce a constant image where all the pixels must have the same value x (25, 51, 76,... and so on).
  When I generate the video using MJPG Encoder :

  vw = cv2.VideoWriter('./videos/input/gray1.mp4',
  
          cv2.VideoWriter_fourcc(*'MJPG'),
  
          fps,(resolution[1],resolution[0]))

  and read the output using the VideoCapture class, everything just works fine. I got a frame array with all pixel values set to (25,51,76 and so on).
  However when I generate the video using HEV1 (H.265) or also H264 :

  vw = cv2.VideoWriter('./videos/input/gray1.mp4',
  
          cv2.VideoWriter_fourcc(*'HEV1'),
  
          fps,(resolution[1],resolution[0]))

  I run into the following issue. The frame I got in BGR format follows the next configuration :

  • The blue channel value is the expected value (x) minus 4 (25-4=21, 51-4=47, 76-4=72, and so on).
  • The green channel is the expected value (x) minus 1 (25-1=24, 51-1=50, 76-1=75).
  • The red channel is the expected value (x) minus 3 (25-3=22, 51-3=48, 76-3=73).

  Notice that the value is reduced with a constant value of 4,1,3, independently of the pixel value (so there is a constant effect).
  What I could explain is a pixel value dependable feature, instead of a fixed one.
  What is worse is that if I choose to generate a video with frames consisting in every color (pixel values [255 0 0],[0 255 0] and [0 0 255]) I get the corresponding outputs values ([251 0 0],[0 254 0] and [0 0 252])
  I though that this relation was related to the grayscale Y value, where :

  Y = 76/256 * RED + 150/256 * GREEN + 29/256 * BLUE

  But this coefficients are not related with the output obtained. Maybe the problem is the reading with VideoCapture ?

  EDIT :
  In case that I want to have the same output value for the pixels (Ej : [10,10,10] experimentally I have to create a img where the red and blue channel has the green channel value plus 2 :

  value = 10
  
  img = np.zeros((resolution[0],resolution[1],3),dtype=np.uint8)+value
  
      img[:,:,2]=img[:,:,2]+2
  
      img[:,:,1]=img[:,:,1]+0
  
      img[:,:,0]=img[:,:,0]+2

  Anyone has experience this issue ? It is related to the encoding process or just that OpenCV treats the image differently, prior encoding, depending on the fourcc parameter value ?

• Python UnicodeEncodeError : 'charmap' codec can't encode when using GEOPY

  23 février 2021, par Tony Roczz

  I have been fiddling with python geopy and I tried the basic commands given in the documentation. But I am getting the UnicodeEncodeError when trying the raw command(to geolocate a query to an address and coordinates)

  



  print(location.raw)


  



  Error UnicodeEncodeError: &#x27;charmap&#x27; codec can&#x27;t encode character &#x27;\xa9&#x27; in position 83: character maps to <undefined></undefined>

  



  Then I tried the other way around (To find the address corresponding to a set of coordinates)

  



  print(location.address)    


  



  I am getting the same error UnicodeEncodeError: &#x27;charmap&#x27; codec can&#x27;t encode character &#x27;\u0101&#x27; in position 10: character maps to <undefined></undefined>

  



  I tried print((location.address).encode("utf-8")) , now am not getting any error but the output printed is like this b'NH39, Mirz\xc4\x81pur

  



  and when using print((location.raw).encode("utf-8")) I am getting error

  



  AttributeError: 'dict' object has no attribute 'encode'


  



  Can anyone tell me what is going on here and what I should do to get a proper output ?

  



  Edit :(After being marked as duplicate)

  



  Based on the solution given in this problem I am reporting on how it does not solve my problem

  



  What I wanted to know is why do I get the UnicodeEncodeError when trying out the basic sample codings given in the documentation and it did answer for that.

  



  If I want to use it an application how do I solve the error and I cannot have the application running on separate IDE or send the output to a external file since my application will function based on the output from geopy, I want the application to run in the terminal as my other applications do.

  


• Python UnicodeEncodeError : 'charmap' codec can't encode when using GEOPY

  9 août 2015, par Tony Roczz

  I have been fiddling with python geopy and I tried the basic commands given in the documentation. But I am getting the UnicodeEncodeError when trying the raw command(to geolocate a query to an address and coordinates)

  print(location.raw)

  Error UnicodeEncodeError: 'charmap' codec can't encode character '\xa9' in position 83: character maps to <undefined></undefined>

  Then I tried the other way around (To find the address corresponding to a set of coordinates)

  print(location.address)    

  I am getting the same error UnicodeEncodeError: 'charmap' codec can't encode character '\u0101' in position 10: character maps to <undefined></undefined>

  I tried print((location.address).encode("utf-8")) , now am not getting any error but the output printed is like this b'NH39, Mirz\xc4\x81pur

  and when using print((location.raw).encode("utf-8")) I am getting error

  AttributeError: 'dict' object has no attribute 'encode'

  Can anyone tell me what is going on here and what I should do to get a proper output ?

  Edit :(After being marked as duplicate)

  Based on the solution given in this problem I am reporting on how it does not solve my problem

  What I wanted to know is why do I get the UnicodeEncodeError when trying out the basic sample codings given in the documentation and it did answer for that.

  If I want to use it an application how do I solve the error and I cannot have the application running on separate IDE or send the output to a external file since my application will function based on the output from geopy, I want the application to run in the terminal as my other applications do.