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• Python cv2 script that scans a giant image to a video. Raises error : Unknown C++ exception from OpenCV code

  26 avril 2022, par Nolrenea

  I wrote a script that scans a giant image to make a video. Normally I just post my scripts straight to my Code Review account, but this script is ugly, needs to be refactored, implements only horizontal scrolling and contains a bug that I can't get rid of.

  


  It is working but not perfect, I can't get the last line at the bottom of the image, with height of image_height % 1080. If I ignore it, the code is working fine, if I try to fix it, it throws exceptions.

  


  Example :

  


  Original image (Google Drive)

  


  Video Output (Google Drive)

  


  As you can see from the video, everything is working properly except the fact that I can't get the bottom line.

  


  Full working code

  


  ---

  


  import cv2
import numpy as np
import random
import rpack
from fractions import Fraction
from math import prod

def resize_guide(image_size, target_area):
    aspect_ratio = Fraction(*image_size).limit_denominator()
    horizontal = aspect_ratio.numerator
    vertical = aspect_ratio.denominator
    unit_length = (target_area/(horizontal*vertical))**.5
    return (int(horizontal*unit_length), int(vertical*unit_length))

fourcc = cv2.VideoWriter_fourcc(*'h264')
FRAME = np.zeros((1080, 1920, 3), dtype=np.uint8)

def new_frame():
    return np.ndarray.copy(FRAME)

def center(image):
    frame = new_frame()
    h, w = image.shape[:2]
    yoff = round((1080-h)/2)
    xoff = round((1920-w)/2)
    frame[yoff:yoff+h, xoff:xoff+w] = image
    return frame

def image_scanning(file, fps=60, pan_increment=64, horizontal_increment=8, fast_decrement=256):
    image = cv2.imread(file)
    height, width = image.shape[:2]
    assert width*height >= 1920*1080
    video_writer = cv2.VideoWriter(file+'.mp4', fourcc, fps, (1920, 1080))
    fit_height = True
    if height < 1080:
        width = width*1080/height
        image = cv2.resize(image, (width, 1080), interpolation = cv2.INTER_AREA)
    aspect_ratio = width / height
    zooming_needed = False
    if 4/9 <= aspect_ratio <= 16/9:
        new_width = round(width*1080/height)
        fit = cv2.resize(image, (new_width, 1080), interpolation = cv2.INTER_AREA)
        zooming_needed = True
    
    elif 16/9 < aspect_ratio <= 32/9:
        new_height = round(height*1920/width)
        fit = cv2.resize(image, (1920, new_height), interpolation = cv2.INTER_AREA)
        fit_height = False
        zooming_needed = True
    
    centered = center(fit)
    for i in range(fps):
        video_writer.write(centered)
    if fit_height:
        xoff = round((1920 - new_width)/2)
        while xoff:
            if xoff - pan_increment >= 0:
                xoff -= pan_increment
            else:
                xoff = 0
            frame = new_frame()
            frame[0:1080, xoff:xoff+new_width] = fit
            video_writer.write(frame)
    else:
        yoff = round((1080 - new_height)/2)
        while yoff:
            if yoff - pan_increment >= 0:
                yoff -= pan_increment
            else:
                yoff = 0
            frame = new_frame()
            frame[yoff:yoff+new_height, 0:1920] = fit
            video_writer.write(frame)
    
    if zooming_needed:
        if fit_height:
            width_1, height_1 = new_width, 1080
        else:
            width_1, height_1 = 1920, new_height
        new_area = width_1 * height_1
        original_area = width * height
        area_diff = original_area - new_area
        unit_diff = area_diff / fps
        for i in range(1, fps+1):
            zoomed = cv2.resize(image, resize_guide((width_1, height_1), new_area+unit_diff*i), interpolation=cv2.INTER_AREA)
            zheight, zwidth = zoomed.shape[:2]
            zheight = min(zheight, 1080)
            zwidth = min(zwidth, 1920)
            frame = new_frame()
            frame[0:zheight, 0:zwidth] = zoomed[0:zheight, 0:zwidth]
            video_writer.write(frame)
    y, x = 0, 0
    completed = False
    while y != height - 1080:
        x = 0
        while x != width - 1920:
            if x + horizontal_increment + 1920 <= width:
                x += horizontal_increment
                frame = image[y:y+1080, x:x+1920]
                video_writer.write(frame)
            else:
                x = width - 1920
                frame = image[y:y+1080, x:x+1920]
                for i in range(round(fps/3)):
                    video_writer.write(frame)
                if y == height - 1080:
                    completed = True
        while x != 0:
            if x - fast_decrement - 1920 >= 0:
                x -= fast_decrement
            else:
                x = 0
            frame = image[y:y+1080, x:x+1920]
            video_writer.write(frame)
        if y + 2160 <= height:
            y += 1080
        else:
            y = height - 1080
    cv2.destroyAllWindows()
    video_writer.release()
    del video_writer


  


  The above the the code needed to produce the example video. It is working but the bottom line is missing.

  


  Now if I change the last few lines to this :

  


          if y + 2160 <= height:
            y += 1080
        else:
            y = height - 1080
            x = 0
            while x != width - 1920:
                if x + horizontal_increment + 1920 <= width:
                    x += horizontal_increment
                    frame = image[y:y+1080, x:x+1920]
                    video_writer.write(frame)
    cv2.destroyAllWindows()
    video_writer.release()
    del video_writer


  


  I expect it to include the bottom line, but it just throws exceptions instead :

  


  OpenCV: FFMPEG: tag 0x34363268/&#x27;h264&#x27; is not supported with codec id 27 and format &#x27;mp4 / MP4 (MPEG-4 Part 14)&#x27;&#xA;OpenCV: FFMPEG: fallback to use tag 0x31637661/&#x27;avc1&#x27;&#xA;---------------------------------------------------------------------------&#xA;error                                     Traceback (most recent call last)&#xA; in <module>&#xA;----> 1 image_scanning("D:/collages/91f53ebcea2a.png")&#xA;&#xA; in image_scanning(file, fps, pan_increment, horizontal_increment, fast_decrement)&#xA;    122                     x &#x2B;= horizontal_increment&#xA;    123                     frame = image[y:y&#x2B;1080, x:x&#x2B;1920]&#xA;--> 124                     video_writer.write(frame)&#xA;    125     cv2.destroyAllWindows()&#xA;    126     video_writer.release()&#xA;&#xA;error: Unknown C&#x2B;&#x2B; exception from OpenCV code&#xA;</module>

  


  (If you can't get the example code working I can't help you, but I am using Python 3.9.10 x64 on Windows 10, and I have this file : "C :\Windows\System32\openh264-1.8.0-win64.dll", the '.avi' format generates video files with Gibibytes (binary unit, not SI Gigabyte) of size)

  


  How to get rid of the exception ?

  


• docker service create : How to deal with custom or unknown parameter needed by linuxserver/ffmpeg image ?

  24 mai 2022, par Mike

  I am new to docker and docker swarm and started dockerizing several services and am trying to get them running as docker swarm services. I ran into a road block with the linuxserver/ffmpeg image :

  


  

  1. it uses a —device parameter which is not implemented in create service

  


  2. it expects several custom parameters to pass them to the ffmpeg encoder

  


  


  From my research up to now I assume that passing parameters is not implemented in docker create service, but maybe you can think of a workaround ? (unfortunately the image does not process environment variables, or at least they are not documented)

  


  This is how I start dockerized ffmpeg (working fine in standalone mode) :

  


  docker run -d /
  
—network="host" /
  
—device=/dev/video0 :/dev/video0 / ### error : unknow flag
  
—name ffmpeg_streamer /
  
—restart always -it /
  
-v $(pwd)/video :/video /
  
linuxserver/ffmpeg / ### custom parameters below here
  
-stream_loop /
  
-1 -re -nostdin /
  
-i "/video/test.avi" /
  
-f pulse /
  
-vcodec libx264 /
  
-preset:v veryfast /
  
-b:v 400k /
  
-f flv rtmp ://localhost:1935/live/streamkey

  


  Many thanks for looking into this !

  


• ffmpeg -vcodec is not working , unknown encoder [closed]

  24 mai 2022, par Younghwan Kim

  i want to use ffmpeg to encode ,
but i guess it's not working '-vcodec' option,

  


  command :

  


   ffmpeg -i test.mp4 -vcodec videocodec -acodec audiocodec test.flv 2>&1


  


  output :

  


    libswresample   4.  3.100 /  4.  3.100
  libpostproc    56.  3.100 / 56.  3.100
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'test.mp4':
  Metadata:
  major_brand     : isom
  minor_version   : 512
  compatible_brands: isomiso2avc1mp41
  encoder         : Lavf58.45.100
  Duration: 00:02:34.40, start: 0.000000, bitrate: 934 kb/s
  Stream #0:0[0x1](und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(progressive), 
  1916x1032 [SAR 1:1 DAR 479:258], 921 kb/s, 30 fps, 30 tbr, 15360 tbn (default)
  Metadata:
  handler_name    : VideoHandler
  vendor_id       : [0][0][0][0]
  Stream #0:1[0x2](eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 4 kb/s 
  (default)
  Metadata:
  handler_name    : AAC Audio Track
  vendor_id       : [0][0][0][0]
  **Unknown encoder 'videocodec'**


  


  how can i figure it out ?