yuv转bgr

import time
from ctypes import *

import cv2

import numpy as np


def yuv2bgr(file_name, height, width, start_frame):
    fp = open(file_name, 'rb')
    fp.seek(0, 2)  # 设置文件指针到文件流的尾部 + 偏移 0
    fp_end = fp.tell()  # 获取文件尾指针位置

    frame_size = height * width * 3 // 2  # 一帧图像所含的像素个数
    num_frame = fp_end // frame_size  # 计算 YUV 文件包含图像数
    print("This yuv file has {} frame imgs!".format(num_frame))
    fp.seek(frame_size * start_frame, 0)  # 设置文件指针到文件流的起始位置 + 偏移 frame_size * startframe
    print("Extract imgs start frame is {}!".format(start_frame + 1))

    start=time.time()
    yyyy_uv = np.zeros(shape=frame_size, dtype='uint8', order='C')
    for j in range(frame_size):
        yyyy_uv[j] = ord(fp.read(1))  # 读取 YUV 数据，并转换为 unicode

    img = yyyy_uv.reshape((height * 3 // 2, width)).astype('uint8')  # NV12 的存储格式为：YYYY UV