是他们从 python 在 linux 中运行多进程终端命令的方法

Question

I tried to run this code in order to change the file type of a folder of.MOV files to.mp4 files I am trying to do this in multiprocessing because the file type changing is really CPU consuming.:

the code

def change_video_file_type_for_multy_proccecing(file_path):
   os.system('ffmpeg -i ' + file_path+ ' -vcodec h264 -acodec mp2 -q:v 0 ' + file_path.replace(".MOV",".mp4"))

input_for_after_trim = "/home/oem/Documents/2021/MOV/after_trim"
output_for_after_trim = "/home/oem/Documents/2021/mp4/after_trim"
file_path_list = []
for filename in os.listdir(input_for_after_trim):
   file_path_list.append(input_for_after_trim+"/"+filename)
with concurrent.futures.ProcessPoolExecutor() as executor:
   # other way
   results = executor.map(change_video_file_type_for_multy_proccecing,file_path_list)  # will return the result of the function by calling order

the problem:

but when I run it like that but somehow some files are created but stop in early-stage and it saves a 23-byte file means the command stoped at the beginning and some other files change their file type very good.

it is not because a problem in the terminal command because when i did it synchronize (without multithreading it went fine but really slow)

my computer details:

Linux Ubuntu 21.04 kernel 5.11.0-41-generic

Answer 1

Does this fix your issues?

from multiprocessing import Pool
import os

def change_video_file_type_for_multy_proccecing(file_path):
   os.system('ffmpeg -i ' + file_path+ ' -vcodec h264 -acodec mp2 -q:v 0 ' + file_path.replace(".MOV",".mp4"))

input_for_after_trim = "/home/oem/Documents/2021/MOV/after_trim"
output_for_after_trim = "/home/oem/Documents/2021/mp4/after_trim"
file_path_list = []
for filename in os.listdir(input_for_after_trim):
   file_path_list.append(input_for_after_trim+"/"+filename)

num_processes = os.cpu_count() #just an example, set to what you want
with Pool(num_processes) as p:
   results = list(p.map(change_video_file_type_for_multy_proccecing,file_path_list))