dsh/dual_camera_system/video_lock.py

"""
全局视频捕获锁
防止多个VideoCapture并发read()导致FFmpeg async_lock崩溃

FFmpeg内部使用共享线程池解码，多个VideoCapture.read()并发调用
会触发 pthread_frame.c:167 的 async_lock 断言失败导致进程崩溃。
此模块提供全局锁，序列化所有read()调用。
"""

import threading

# 全局锁：所有VideoCapture.read()必须持有此锁
_ffmpeg_lock = threading.Lock()


def acquire_ffmpeg_lock():
    """获取FFmpeg全局锁"""
    _ffmpeg_lock.acquire()


def release_ffmpeg_lock():
    """释放FFmpeg全局锁"""
    _ffmpeg_lock.release()


class FFLockContext:
    """with语句用法: with ff_lock(): cap.read()"""
    def __enter__(self):
        _ffmpeg_lock.acquire()
        return self

    def __exit__(self, *args):
        _ffmpeg_lock.release()


# 便捷别名
ff_lock = FFLockContext