解决录制音视频不同步问题

问题

使用opencv录制视频，同时使用pyaudio录制音频，存在两个问题

1.视频录制和音频录制没有同时启动，开始时间对不上

2.视频录制时长和视频保存后的时长不一致，会出现视频变慢的现象

解决方法

1.使用event事件，使两个录制同步开始

2.读取音频视频时长，调整视频帧率，把视频时长调整成和音频一样长，再把音频合并到视频中。

源代码

import os
import threading
import time
import wave
from datetime import datetime

import cv2
import pyaudio
from moviepy.editor import *
    
#全局变量，控制录制停止
allowRecord=False
cap=None
#录像
def record_video(event):
    global cap
    cap=cv2.VideoCapture(0+ cv2.CAP_DSHOW)
    writer=cv2.VideoWriter('output.mp4',cv2.VideoWriter_fourcc(*'MJPG'),25,(640,480))
    event.set()
    global allowRecord
    allowRecord=True#录制启动
    print('录像开始时间：'+datetime.now().strftime('%Y-%m-%d %H:%M:%S.%f'))
    while allowRecord==True:
        ret,frame=cap.read()
        if ret:
            writer.write(frame)
    print('录像结束时间：'+datetime.now().strftime('%Y-%m-%d %H:%M:%S.%f'))
    allowRecord=False
    cap.release()
    
#录音
def record_audio(event):
    global allowRecord
    #等待event启动录制音频
    p=pyaudio.PyAudio()
    global stream
    stream=p.open(format=pyaudio.paInt16,channels=1,rate=16000,input=True,frames_per_buffer=1024)
    wf = wave.open('output.wav', 'wb')
    wf.setnchannels(1)
    wf.setsampwidth(p.get_sample_size(pyaudio.paInt16))
    wf.setframerate(16000)
    event.wait()
    #输出时间戳,精确到毫秒
    print('录音开始时间：'+datetime.now().strftime('%Y-%m-%d %H:%M:%S.%f'))
    while allowRecord==True:
        data=stream.read(1024)
        wf.writeframes(data)
    wf.close()
    print('录音结束时间：'+datetime.now().strftime('%Y-%m-%d %H:%M:%S.%f'))
    stream.stop_stream()  # 关闭流
    stream.close()
    p.terminate()
    
#合并视频音频
def merge_video_audio(video_path,audio_path):
    audioclip = AudioFileClip(audio_path)
    videoclip = VideoFileClip(video_path)
    videoclip2 = videoclip.set_audio(audioclip)
    video = CompositeVideoClip([videoclip2])
    filename=datetime.now().strftime('%Y%m%d%H%M%S')
    video.write_videofile(filename+'.mp4', codec='mpeg4', bitrate='1000K') # bitrate 设置比特率，比特率越高， 合并的视频越清晰，视频文件也越大
    audioclip.close()
    videoclip.close()
    videoclip2.close()
    video.close()
    #列出所有进程名,关闭所有包含'ffmpeg'的进程
    process_names=os.popen('tasklist').readlines()
    for name in process_names:
        if 'ffmpeg' in name:
            os.system('taskkill /f /im '+name.split()[0])
    os.remove(video_path)
    os.remove('output.mp4')
    os.rename(audio_path, filename+'.wav')
    print('音视频合并成功：'+filename+'.mp4')

#停止录制
def stop_record():
    global allowRecord
    allowRecord=False
    
def record_video_with_audio():
    event=threading.Event()
    event.clear()
    t1=threading.Thread(target=record_video,args=(event,))
    t2=threading.Thread(target=record_audio,args=(event,))
    #同步开启录制
    t1.start()
    t2.start()
    while allowRecord==False:#等待录制启动
        time.sleep(0.05)
    while allowRecord:#等待录制停止
        time.sleep(0.05)
        continue
        
    #结束线程
    t1.join()
    t2.join()
    video_path='output.mp4'
    audio_path='output.wav'
    #查看时长
    video_time=VideoFileClip(video_path).duration
    audio_time=AudioFileClip(audio_path).duration
    print('视频时长：'+str(video_time)+' s')
    print('音频时长：'+str(audio_time)+' s')
    #把视频压缩的和音频一样长
    # Load the video
    video = cv2.VideoCapture(video_path)
    # Get the frame rate
    fps = video.get(cv2.CAP_PROP_FPS)
    new_fps=video_time/audio_time*fps
    print('调整视频帧率为：'+str(new_fps))
    # Set the frame rate
    video.set(cv2.CAP_PROP_FPS, new_fps)
    video_writer = cv2.VideoWriter('output_new.mp4', cv2.VideoWriter_fourcc(*'MJPG'), new_fps, (640, 480))
    while True:
        # Read the next frame
        success, frame = video.read()
        if not success:
            break
        # Write the frame to the output video
        video_writer.write(frame)

    # Release the video
    video.release()
    video_writer.release()
    t=threading.Thread(target=merge_video_audio,args=('output_new.mp4','output.wav'))
    t.start()
    
t=threading.Thread(target=record_video_with_audio)
t.start()
time.sleep(10)#录制10s
stop_record()