Pygame's multimedia output capabilities are severily limited: It can only save uncompressed BMP images, and there is no way it can save a video format.
You have to make use of another library which to feed image frames, to render the video - or save frame by frame in a folder, numbering the file names in crescent order, and convert the result to a video with an utility later.
This project seens to feature a class to call libffmpeg to encode videos, passing frame by frame in a Python call:https://github.com/kanryu/pipeffmpeg- you will just need a way to convert the pygame Surface object to the expected "frameraw" attribute of ffmpeg.
https://github.com/kanryu/pipeffmpeg/blob/master/pipeffmpeg.py
i´m not at home now but my workarround is take the pygame surface and convert to numpy array and write with opencv to mp4 movie.
python - How to capture pygame screen? - Stack Overflow https://stackoverflow.com/questions/6087484/how-to-capture-pygame-screen
background_image_filename = 'sushiplate.jpg'
sprite_image_filename = 'fugu.png'
import pygame
from pygame.locals import *
from sys import exit
pygame.init()
screen = pygame.display.set_mode((640, 480), 0, 32)
background = pygame.image.load(background_image_filename).convert()
sprite = pygame.image.load(sprite_image_filename).convert_alpha()
clock = pygame.time.Clock()
x, y = 100., 100.
speed_x, speed_y = 133., 170.
for event in pygame.event.get():
if event.type == QUIT:
exit()
screen.blit(background, (0, 0))
screen.blit(sprite, (x, y))
time_passed = clock.tick(30)
time_passed_seconds = time_passed / 1000.0
x += speed_x * time_passed_seconds
y += speed_y * time_passed_seconds
# 到达边界则把速度反向
if x > 640 - sprite.get_width():
speed_x = -speed_x
x = 640 - sprite.get_width()
elif x < 0:
speed_x = -speed_x
x = 0.
if y > 480 - sprite.get_height():
speed_y = -speed_y
y = 480 - sprite.get_height()
elif y < 0:
speed_y = -speed_y
y = 0
pygame.image.save(screen, "screenshot.png")
pygame.display.update()