如何在高通RB5开发板上用HAL3/Camera2+OpenCV获取双MIPI摄像头视频？

使用高通RB5开发套件搭配两颗OV9282 MIPI摄像头，尝试通过Gstreamer结合OpenCV访问双目摄像头时遇到以下问题：

• 仅能显示单个摄像头画面
• Gstreamer视频流无法传入cv2.VideoCapture供后续处理

现寻求通过HAL3/Camera2 API结合OpenCV访问双目摄像头的可行方案，以下是尝试的Gstreamer代码：

import cv2
from threading import Thread
from time import sleep
import gi

gi.require_version("Gst", "1.0")
from gi.repository import Gst, GLib

Gst.init(None)

main_loop = GLib.MainLoop()
thread = Thread(target=main_loop.run)
thread.start()

pipeline_str = """
    qtiqmmfsrc camera=1 ! video/x-raw, format=NV12, width=1280, height=720, framerate=15/1 ! videoconvert ! waylandsink 
"""
pipeline = Gst.parse_launch(pipeline_str)
pipeline.set_state(Gst.State.PLAYING)

pipeline_str2 = """
    qtiqmmfsrc camera=3 ! video/x-raw, format=NV12, width=1280, height=720, framerate=15/1 ! videoconvert ! waylandsink
"""
pipeline2 = Gst.parse_launch(pipeline_str2)
pipeline2.set_state(Gst.State.PLAYING)

cap = cv2.VideoCapture(pipeline_str, cv2.CAP_GSTREAMER)
cap2 = cv2.VideoCapture(pipeline_str2, cv2.CAP_GSTREAMER)

num = 0

while True:
    succes1, img = cap.read()
    succes2, img2 = cap2.read()

    if not succes1 or not succes2:
        break

    cv2.imshow('Img 1', img)
    cv2.imshow('Img 2', img2)

    k = cv2.waitKey(5)

    if k == 27:
        break
    elif k == ord('s'):
        cv2.imwrite('images/stereoLeft/imageL{}.png'.format(num), img)
        cv2.imwrite('images/stereoRight/imageR{}.png'.format(num), img2)
        print('images saved!')
        num += 1

cap.release()
cap2.release()
cv2.destroyAllWindows()

pipeline.set_state(Gst.State.NULL)
pipeline2.set_state(Gst.State.NULL)
main_loop.quit()

原Gstreamer代码问题分析 #

1. 资源冲突：同时通过Gst.parse_launch启动Pipeline，又用cv2.VideoCapture加载同一段Pipeline字符串，导致同一摄像头被两个进程抢占，无法正常工作。
2. Sink组件错误：waylandsink是直接输出画面的显示组件，无法将视频流传递给OpenCV的VideoCapture，需替换为appsink作为OpenCV的输入源。

HAL3/Camera2 API + OpenCV 双目访问方案 #

高通RB5原生支持Camera2 API（基于HAL3），以下是Python环境下的实现方案：

1. 环境准备 #

• 安装依赖：pip install opencv-python pycam2
• 权限配置：Linux环境下将当前用户加入video组；Android环境下授予摄像头权限：adb shell pm grant com.your.package android.permission.CAMERA
• 确认摄像头ID：通过pycam2的CameraManager.list_cameras()查看两颗OV9282的设备ID

2. 代码实现 #

import cv2
import numpy as np
from pycam2.camera2 import CameraManager, CameraDevice

# 初始化摄像头管理器
cam_manager = CameraManager()

# 查看可用摄像头（执行一次确认ID后可注释）
# print(cam_manager.list_cameras())

# 绑定双目摄像头（替换为实际ID）
cam_left = CameraDevice(cam_manager, camera_id=0)
cam_right = CameraDevice(cam_manager, camera_id=1)

# 配置摄像头参数
def configure_camera(cam):
    config = cam.create_default_configuration()
    config.set_preview_size((1280, 720))
    config.set_image_format("YUV_420_888")
    config.set_framerate(15)
    return config

config_left = configure_camera(cam_left)
config_right = configure_camera(cam_right)

# 启动摄像头
cam_left.start(config_left)
cam_right.start(config_right)

num = 0
while True:
    # 获取帧数据
    frame_left = cam_left.get_frame()
    frame_right = cam_right.get_frame()

    if frame_left is None or frame_right is None:
        break

    # YUV转BGR格式（适配OV9282输出）
    img_left = cv2.cvtColor(np.array(frame_left.to_yuv()), cv2.COLOR_YUV2BGR_NV12)
    img_right = cv2.cvtColor(np.array(frame_right.to_yuv()), cv2.COLOR_YUV2BGR_NV12)

    # 显示与保存
    cv2.imshow('Left Camera', img_left)
    cv2.imshow('Right Camera', img_right)

    k = cv2.waitKey(5)
    if k == 27:
        break
    elif k == ord('s'):
        cv2.imwrite(f'images/stereoLeft/imageL{num}.png', img_left)
        cv2.imwrite(f'images/stereoRight/imageR{num}.png', img_right)
        print('images saved!')
        num += 1

# 释放资源
cam_left.stop()
cam_right.stop()
cv2.destroyAllWindows()

3. 关键说明 #

• 帧同步：如需严格双目帧同步，可通过Camera2的CaptureRequest配置同步捕获规则，确保左右帧同时采集
• 格式适配：OV9282默认输出NV12格式，需对应使用COLOR_YUV2BGR_NV12转换参数

补充：修复原Gstreamer+OpenCV方案 #

若仍倾向使用Gstreamer，可修改Pipeline使用appsink替代waylandsink，并避免重复创建Pipeline：

import cv2

# 双目摄像头Gstreamer Pipeline（输出为OpenCV兼容的BGR格式）
pipeline_left = "qtiqmmfsrc camera=1 ! video/x-raw, format=NV12, width=1280, height=720, framerate=15/1 ! videoconvert ! video/x-raw, format=BGR ! appsink"
pipeline_right = "qtiqmmfsrc camera=3 ! video/x-raw, format=NV12, width=1280, height=720, framerate=15/1 ! videoconvert ! video/x-raw, format=BGR ! appsink"

cap_left = cv2.VideoCapture(pipeline_left, cv2.CAP_GSTREAMER)
cap_right = cv2.VideoCapture(pipeline_right, cv2.CAP_GSTREAMER)

if not cap_left.isOpened() or not cap_right.isOpened():
    print("无法打开摄像头")
    exit()

num = 0
while True:
    ret_left, img_left = cap_left.read()
    ret_right, img_right = cap_right.read()

    if not ret_left or not ret_right:
        break

    cv2.imshow('Left', img_left)
    cv2.imshow('Right', img_right)

    k = cv2.waitKey(5)
    if k == 27:
        break
    elif k == ord('s'):
        cv2.imwrite(f'images/stereoLeft/imageL{num}.png', img_left)
        cv2.imwrite(f'images/stereoRight/imageR{num}.png', img_right)
        print('images saved!')
        num += 1

cap_left.release()
cap_right.release()
cv2.destroyAllWindows()

内容的提问来源于stack exchange，提问作者Fourier