@veye_xumm 好的，感谢

@veye_xumm IMX287，使用外部的信号输入ADP-N4触发同步

用python多进程为每个相机分别subprocess运行v4l2-ctl命令行然后读取--stream-mmap --verbose的时间戳，这个时间戳的数值在不同相机之间是一致的吗（就是说直接找时间戳最接近的即为同步帧）？还是每个相机的计时器有不同的起始点？

在Jetson AGX Orin上使用ADP-N4连接两个IMX287相机，0号相机接在bus30，1号相机接在bus31
当i2c设置输出为12bit（2）且v4l2也设置pixelformat为XY12的时候，0相机可以以12bit记录，但是1相机会报错
1相机只要i2c设置为2就无法记录，会报错，且即使v4l2设置为12bit也会以8bit记录
报错信息：

v4l2-ctl --stream-mmap --stream-count=1000 -d /dev/video1 --verbose --stream-to=test1.raw
VIDIOC_QUERYCAP: ok
                VIDIOC_REQBUFS returned 0 (Success)
                VIDIOC_QUERYBUF returned 0 (Success)
                VIDIOC_QUERYBUF returned 0 (Success)
                VIDIOC_QUERYBUF returned 0 (Success)
                VIDIOC_QUERYBUF returned 0 (Success)
                VIDIOC_QBUF returned 0 (Success)
                VIDIOC_QBUF returned 0 (Success)
                VIDIOC_QBUF returned 0 (Success)
                VIDIOC_QBUF returned 0 (Success)
                VIDIOC_STREAMON returned 0 (Success)
cap dqbuf: 0 seq:      0 bytesused: 382976 ts: 0.000000 (error, ts-monotonic, ts-src-eof)
cap dqbuf: 1 seq:      1 bytesused: 382976 ts: 0.000000 (error, ts-monotonic, ts-src-eof)
cap dqbuf: 2 seq:      2 bytesused: 382976 ts: 0.000000 (error, ts-monotonic, ts-src-eof)
cap dqbuf: 3 seq:      3 bytesused: 382976 ts: 0.000000 (error, ts-monotonic, ts-src-eof)

i2c设置：

sudo ./mv_mipi_i2c.sh -w -f pixelformat -p1 2 -b 31
w pixelformat is 2

@veye_xumm 经过一番尝试后没能找到，最后是用python多进程为每个相机分别subprocess运行v4l2-ctl命令行然后读取--stream-mmap --verbose的时间戳，目前一切顺利。还想请教一下怎么做real time binning，就是实时地将2x2或者4x4的像素值求和再保存，我们的c水平比较烂哈哈。

@veye_xumm
感谢提醒，更换multi-processing之后帧率就正常了。另一个问题是v4l2-python的版本已经多年没有更新，无法直接获取时间戳，不知道有没有解决方案或者比较成熟的c++案例？

@veye_xumm 测试了200和100fps，实际帧率在67-69左右且不稳定。想请教如何在驱动层做调整？

如题，通过v4l2设置帧率为最大之后，单线程多相机的帧率与外部硬触发频率基本一致，但是波动比较大。然后使用如下代码进行多线程多相机采集，帧率远低于外部硬触发频率。

import cv2
import argparse
import subprocess
import time
import numpy as np

import numpy as np
import cv2
import threading
from copy import deepcopy

thread_lock = threading.Lock()
thread_exit = False

class VideoThread(threading.Thread):
    def __init__(self, camera_id, img_height, img_width):
        super(VideoThread, self).__init__()
        self.camera_id = camera_id
        self.img_height = img_height
        self.img_width = img_width
        self.frame = np.zeros((img_height, img_width, 3), dtype=np.uint8)

    def get_frame(self):
        return deepcopy(self.frame)

    def run(self):
        global thread_exit
        cap = cv2.VideoCapture(self.camera_id)
        cap.set(cv2.CAP_PROP_FRAME_WIDTH, self.img_width)
        cap.set(cv2.CAP_PROP_FRAME_HEIGHT, self.img_height)
        frame_num = 0
        timestampes = []
        while not thread_exit:
            ret, frame = cap.read()
            if ret:
                #thread_lock.acquire()
                self.frame = frame
                if frame_num == 0:
                    time_start = time.perf_counter()
                frame_num = frame_num + 1
                #thread_lock.release()
                print('get' + self.camera_id[-6:] + f'frame {frame_num}')
            else:
                thread_exit = True
            time_end = time.perf_counter()
            time_ms = (time_end - time_start)*1000
            timestampes.append(time_ms)
            if frame_num >= 3000:
                thread_exit = True
                timestampes = np.array(timestampes)
                np.save(self.camera_id[-6:] + '.npy', timestampes)
        cap.release()


def main():
    # Set up command-line argument parser
    parser = argparse.ArgumentParser(description='Real-time display of GREY image from mv-cam')
    parser.add_argument('--roix', type=int, default=0, help='roi start x (default: 0)')
    parser.add_argument('--roiy', type=int, default=0, help='roi start y (default: 0)')
    parser.add_argument('--width', type=int, default=704, help='image width (default: 640)')
    parser.add_argument('--height', type=int, default=544, help='image height (default: 480)')
    parser.add_argument('--fps', type=int, default=320, help='frame rate (default: 30)')
    parser.add_argument('--pixelformat', type=int, default=12, help='pixel format (default: 12)')

    args = parser.parse_args()
    
    v4l2_cmd = f"v4l2-ctl --set-ctrl roi_x={args.roix}"
    subprocess.run(v4l2_cmd, shell=True)
    
    v4l2_cmd = f"v4l2-ctl --set-ctrl roi_y={args.roiy}"
    subprocess.run(v4l2_cmd, shell=True)
    
    v4l2_cmd = f"v4l2-ctl --set-fmt-video=width={args.width},height={args.height}"
    subprocess.run(v4l2_cmd, shell=True)
    
    v4l2_cmd = f"v4l2-ctl --set-ctrl frame_rate={args.fps}"
    subprocess.run(v4l2_cmd, shell=True)

    v4l2_cmd = "v4l2-ctl --set-ctrl low_latency_mode=1"
    subprocess.run(v4l2_cmd, shell=True)

    v4l2_cmd = f"v4l2-ctl --set-ctrl pixelformat=XY{args.pixelformat}"
    subprocess.run(v4l2_cmd, shell=True)

    #v4l2_cmd = "v4l2-ctl --set-ctrl exposure_auto=1"
    #subprocess.run(v4l2_cmd, shell=True)

    #v4l2_cmd = "v4l2-ctl --set-ctrl exposure_absulute=20"
    #subprocess.run(v4l2_cmd, shell=True)

    v4l2_cmd = "v4l2-ctl --set-ctrl trigger_mode=1"
    subprocess.run(v4l2_cmd, shell=True)

    v4l2_cmd = "v4l2-ctl --set-ctrl trigger_src=1"
    subprocess.run(v4l2_cmd, shell=True)

    v4l2_cmd = "v4l2-ctl --set-ctrl vi_time_out_disable=1"
    subprocess.run(v4l2_cmd, shell=True)


    global thread_exit
    img_height = args.height
    img_width = args.width

    thread_0 = VideoThread('/dev/video0', img_height, img_width)
    thread_1 = VideoThread('/dev/video1', img_height, img_width)
    thread_0.start()
    thread_1.start()
    #frame_num = 0
    while not thread_exit:
        #thread_lock.acquire()
        #frame_0 = thread_0.get_frame()
        #print(f'get cam0 {frame_num}')
        #frame_1 = thread_1.get_frame()
        #print(f'get cam1 {frame_num}')
        #thread_lock.release()
        #thread_0.join()
        #thread_1.join()
        #frame_num = frame_num + 1
        #if frame_num >= 3000:
            #thread_exit = True
        pass
    print('done!')
    # Release resources
    v4l2_cmd = "v4l2-ctl --set-ctrl vi_time_out_disable=0"
    subprocess.run(v4l2_cmd, shell=True)

if __name__ == '__main__':
    main()