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• Broken *.m3u8 file [closed]

  26 mai 2013, par Wildan Muhlis

  I have created this file using ffmpeg.
  Does Anyone know what's wrong with this *.m3u8 file ?

  http://202.89.117.50/hilal/global_assets/temp/7580338/bogor.m3u8

  It could played in VLC but couldn't played in browser and other media such as jwPlayer.

• The Fastest Way To Learn Assembly Language

  4 septembre 2011, par Multimedia Mike — Programming

  I saw an old StackOverflow thread linked from Hacker News asking how to whether it’s worthwhile to learn assembly language and how to go about doing so. I’d like to take a stab at the last question.

  The fastest way to learn an assembly language is to reverse engineer something. Seriously, start with something that you know (like a C program that you wrote yourself) and take it apart. The good news is that assembly language is very simple and you will get a lot of practice in a short amount of time with RE.

  So here’s how you do it :

  • Take a simple program in C and build it with your tool chain, whether GNU gcc on Linux, Xcode on Mac, or MSVC on Windows. Also, make sure to turn on debugging symbols during compilation (this will help annotate the disassembly).
  • On Linux, use objdump : objdump -d program_binary
  • On Mac, use otool : otool -tV program_binary
  • On Windows : I admit, I’m a bit fuzzy on this one– I’m quite certain there’s a standard MSVC tool that prints the assembly listing.

  Anyway, look at the disassembled code and find the main() function. Work from there. Whatever the first instruction is, look it up on Google. You’ll likely find various CPU manuals that will explain the simple operation of the instruction. Look up the next unfamiliar instruction, then the next. Trust me, you’ll become an ASM expert in no time.

  Good luck !

• Variable fps (frame per second) in cv2

  17 octobre 2022, par Sepide

  I use cv2 for creating videos from different frames that I have. When I create the video, I cannot change the fps (frame per second). I want the video be slow at the beginning but fast towards the end, meaning small fps at the beginning but large ones towards the end. However, when I instantiate cv2.VideoWriter I cannot change the fps anymore. What should I do ?

  


  Replicable code

  


  import numpy as np
import cv2, os
import matplotlib

image_size = 200
def create_image_array(image_size):
  image_array = np.random.randn(image_size, image_size)
  row = np.random.randint(0, image_size)
  image_array[row, :] = 100
  return image_array

frame_numbers = 200
for i in range(frame_numbers):
  image_array = create_image_array(image_size)
  matplotlib.image.imsave(f'./shots/frame_{i:03d}.png', image_array)

def make_a_video(shots_folder, video_path):

    shots_folder = 'shots'
    fps = 25
    images = [img for img in os.listdir(shots_folder) if img.endswith(".png")]

    images = sorted(images)[:]
    frame = cv2.imread(os.path.join(shots_folder, images[0]))
    height, width, layers = frame.shape

    video = cv2.VideoWriter(video_path, cv2.VideoWriter_fourcc(*'mp4v'), fps, (width, height))

    for image in images:
        video.write(cv2.imread(os.path.join(shots_folder, image)))

    cv2.destroyAllWindows()
    video.release()

shots_folder = 'shots'
video_path = 'video.mp4'  
make_a_video(shots_folder, video_path)