Mass Convert MP4/AVI clips to GIF with a multithreaded Python function, using a variable to set number of threads required.

convert.py

import imageio
import os, sys
import glob
import threading
import time

class TargetFormat(object):
    GIF = ".gif"
    MP4 = ".mp4"
    AVI = ".avi"

def filenameFromPath(inputpath):
    return inputpath.split("\\")[-1:][0]

def convertFile(inputpath, targetFormat):
    
    """Reference: http://imageio.readthedocs.io/en/latest/examples.html#convert-a-movie"""
    
    filename = filenameFromPath(inputpath)
    outputpath = "outputfiles\\" + filename.split(".")[0] + targetFormat  
    reader = imageio.get_reader(inputpath)
    fps = reader.get_meta_data()['fps']

    writer = imageio.get_writer(outputpath, fps=fps)
    for i,im in enumerate(reader):
        writer.append_data(im)
    writer.close()
    print("\t\tFinished: \t{0}".format(filenameFromPath(inputpath)))
    
def createThread(threads, inputpath):
    t = threading.Thread(name = filenameFromPath(inputpath), target=convertFile, args=(inputpath,TargetFormat.GIF)) 
    threads.append(t)
    t.start()

def main():
    maxThreads = 9
    index = 0
    conv_list = glob.glob("convertfiles\\*.mp4")  
    threads = []
    while (len(threads)<len(conv_list)):
        if (len(threads) - len([t for t in threads if not t.is_alive()]) < maxThreads):
            inputpath = conv_list[index];
            print("File {0} of {1}\tStarted: \t{2}".format(index+1, len(conv_list),filenameFromPath(inputpath)))
            createThread(threads, conv_list[index] )
            index+=1

if __name__ == '__main__':main()