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• Real time playback of two blended videos with alpha channel and synched audio in pygame ?

  22 décembre 2024, par Francesco Calderone

  I need to play two videos with synched sound in real-time with Pygame.
Pygame does not currently support video streams, so I am using a ffmpeg subprocess.
The first video is a prores422_hq. This is a background video with no alpha channel.
The second video is a prores4444 overlay video with an alpha channel, and it needs to be played in real-tim on top of the first video (with transparency).
All of this needs synched sound from the first base video only.

  


  I have tried many libraries, including pymovie pyav and opencv. The best result so far is to use a subprocess with ffmpeg.

  


  ffmpeg -i testing/stefano_prores422_hq.mov -stream_loop -1 -i testing/key_prores4444.mov -filter_complex "[1:v]format=rgba,colorchannelmixer=aa=1.0[overlay];[0:v][overlay]overlay" -f nut pipe:1 | ffplay -

  


  When running this in the terminal and playing with ffplay, everything is perfect, the overlay looks good, no dropped frames, and the sound is in synch.

  


  However, trying to feed that to pygame via a subprocess creates either video delays and drop frames or audio not in synch.

  


  EXAMPLE ONE :

  


  # SOUND IS NOT SYNCHED - sound is played via ffplay
import pygame
import subprocess
import numpy as np
import sys

def main():
    pygame.init()
    screen_width, screen_height = 1920, 1080
    screen = pygame.display.set_mode((screen_width, screen_height))
    pygame.display.set_caption("PyGame + FFmpeg Overlay with Audio")
    clock = pygame.time.Clock()

    # LAUNCH AUDIO-ONLY SUBPROCESS
    audio_cmd = [
        "ffplay",
        "-nodisp",          # no video window
        "-autoexit",        # exit when video ends
        "-loglevel", "quiet",
        "testing/stefano_prores422_hq.mov"
    ]
    audio_process = subprocess.Popen(audio_cmd)

    # LAUNCH VIDEO-OVERLAY SUBPROCESS
    ffmpeg_command = [
        "ffmpeg",
        "-i", "testing/stefano_prores422_hq.mov",
        "-stream_loop", "-1",         # loop alpha video
        "-i", "testing/key_prores4444.mov",
        "-filter_complex",
        "[1:v]format=rgba,colorchannelmixer=aa=1.0[overlay];"  # ensure alpha channel
        "[0:v][overlay]overlay",      # overlay second input onto first
        "-f", "rawvideo",             # output raw video
        "-pix_fmt", "rgba",           # RGBA format
        "pipe:1"                      # write to STDOUT
    ]
    video_process = subprocess.Popen(
        ffmpeg_command,
        stdout=subprocess.PIPE,
        stderr=subprocess.DEVNULL
    )
    frame_size = screen_width * screen_height * 4  # RGBA = 4 bytes/pixel
    running = True
    while running:
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                running = False
                break

        raw_frame = video_process.stdout.read(frame_size)

        if len(raw_frame) < frame_size:
            running = False
            break
        # Convert raw bytes -> NumPy array -> PyGame surface
        frame_array = np.frombuffer(raw_frame, dtype=np.uint8)
        frame_array = frame_array.reshape((screen_height, screen_width, 4))
        frame_surface = pygame.image.frombuffer(frame_array.tobytes(), 
                                                (screen_width, screen_height), 
                                                "RGBA")
        screen.blit(frame_surface, (0, 0))
        pygame.display.flip()
        clock.tick(25)
    video_process.terminate()
    video_process.wait()
    audio_process.terminate()
    audio_process.wait()
    pygame.quit()
    sys.exit()

if __name__ == "__main__":
    main()



  


  EXAMPLE TWO

  


  # NO VIDEO OVERLAY - SOUND SYNCHED
import ffmpeg
import pygame
import sys
import numpy as np
import tempfile
import os

def extract_audio(input_file, output_file):
    """Extract audio from video file to temporary WAV file"""
    (
        ffmpeg
        .input(input_file)
        .output(output_file, acodec='pcm_s16le', ac=2, ar='44100')
        .overwrite_output()
        .run(capture_stdout=True, capture_stderr=True)
    )

def get_video_fps(input_file):
    probe = ffmpeg.probe(input_file)
    video_info = next(s for s in probe['streams'] if s['codec_type'] == 'video')
    fps_str = video_info.get('r_frame_rate', '25/1')
    num, den = map(int, fps_str.split('/'))
    return num / den

input_file = "testing/stefano_prores422_hq.mov"

# Create temporary WAV file
temp_audio = tempfile.NamedTemporaryFile(suffix='.wav', delete=False)
temp_audio.close()
extract_audio(input_file, temp_audio.name)

probe = ffmpeg.probe(input_file)
video_info = next(s for s in probe['streams'] if s['codec_type'] == 'video')
width = int(video_info['width'])
height = int(video_info['height'])
fps = get_video_fps(input_file)

process = (
    ffmpeg
    .input(input_file)
    .output('pipe:', format='rawvideo', pix_fmt='rgb24')
    .run_async(pipe_stdout=True)
)

pygame.init()
pygame.mixer.init(frequency=44100, size=-16, channels=2, buffer=4096)
clock = pygame.time.Clock()
screen = pygame.display.set_mode((width, height))

pygame.mixer.music.load(temp_audio.name)
pygame.mixer.music.play()

frame_count = 0
start_time = pygame.time.get_ticks()

while True:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            pygame.mixer.music.stop()
            os.unlink(temp_audio.name)
            sys.exit()

    in_bytes = process.stdout.read(width * height * 3)
    if not in_bytes:
        break

    # Calculate timing for synchronization
    expected_frame_time = frame_count * (1000 / fps)
    actual_time = pygame.time.get_ticks() - start_time
    
    if actual_time < expected_frame_time:
        pygame.time.wait(int(expected_frame_time - actual_time))
    
    in_frame = (
        np.frombuffer(in_bytes, dtype="uint8")
        .reshape([height, width, 3])
    )
    out_frame = pygame.surfarray.make_surface(np.transpose(in_frame, (1, 0, 2)))
    screen.blit(out_frame, (0, 0))
    pygame.display.flip()
    
    frame_count += 1

pygame.mixer.music.stop()
process.wait()
pygame.quit()
os.unlink(temp_audio.name)


  


  I also tried using pygame mixer and a separate mp3 audio file, but that didn't work either. Any help on how to synch the sound while keeping the playback of both videos to 25 FPS would be greatly appreciated !!!

  


• Evolution #3089 : Suppression des rubriques : informer des liens qui empêchent

  11 août 2014, par Fil Up

  un message de neofutur qui dit quelque chose de similaire :

  ```
  09:41 (02:58) < neofutur>
  http://forum.spip.net/fr_256464.html#forum258451
  09:41 (02:58) < neofutur> a priori des tas de gens ont ce probleme
  09:41 (03:00) < neofutur> empecher la suppression de la sous
  rubrique vide parce qu elle a une photo associee en tant que
  logo . . . ca meriterai une explication
  09:41 (05:04) < neofutur> peut etre avoir un bouton "supprimer" qyi
  est inactif ( greyed ) avec un survol qui dit "supprimer d
  abord le logo . . ."
  ```

• Evolution #2999 (Nouveau) : Pourvoir personnaliser le contenu de la constante _IS_BOT

  13 mai 2013, par - Equipement

  Bonjour,

  Les signatures des moteurs d’indexations sont définies dans ecrire/inc_version.php, AVANT le chargement du fichier mes_options.php (et avant le chargement des plugins).

  Aussi, je ne vois pas comment on peut compléter cette liste de signatures via le fichier mes_options.php où via un plugin.

  Lorsqu’on utilise mnogosearch sur des sites intranets, ce serait commode.
  Par ailleurs, d’autres ont eu également ce besoin : http://forum.spip.net/fr_247990.html

  Cordialement
  Equipement