Opencv 在VLC播放器Ubuntu 12.04上同时打开2个USB摄像头

如何打开相机： 在终端中（$prompt=我键入的命令后的文本）：\uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu

$ ls /dev/video*
/dev/video0  /dev/video1
$ vlc v4l2:///dev/video0
VLC media player 2.0.8 Twoflower (revision 2.0.8a-0-g68cf50b)
[0x9f2d908] main libvlc: Running vlc with the default interface. Use 'cvlc' to use vlc without interface.

VLC开始播放相机输出

在另一个新终端中（粗体=我键入的命令）：

没有播放视频，只有错误消息

主要目标：我想在opencv（c++）中同时打开两个摄像头。。。opencv也有类似的错误。。所以我用VLC播放器来调试这个问题。 用C++ OpenCV同时打开两台摄像机时的误差（代码相似）

更新7/24： 这个Ubuntu 12.04（32位）是运行在VMware Fusion上的来宾操作系统。这里的主机操作系统是在Mac Pro计算机硬件上运行的OSX 10.9.4

$ lsusb -t
/:  Bus 02.Port 1: Dev 1, Class=root_hub, Driver=uhci_hcd/2p, 12M
    |__ Port 1: Dev 2, If 0, Class=HID, Driver=usbhid, 12M
    |__ Port 2: Dev 3, If 0, Class=hub, Driver=hub/7p, 12M
        |__ Port 1: Dev 4, If 0, Class='bInterfaceClass 0xe0 not yet handled', Driver=btusb, 12M
        |__ Port 1: Dev 4, If 1, Class='bInterfaceClass 0xe0 not yet handled', Driver=btusb, 12M
/:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=ehci_hcd/6p, 480M
    |__ Port 1: Dev 6, If 0, Class='bInterfaceClass 0x0e not yet handled', Driver=uvcvideo, 480M
    |__ Port 1: Dev 6, If 1, Class='bInterfaceClass 0x0e not yet handled', Driver=uvcvideo, 480M
    |__ Port 2: Dev 7, If 0, Class='bInterfaceClass 0x0e not yet handled', Driver=uvcvideo, 480M
    |__ Port 2: Dev 7, If 1, Class='bInterfaceClass 0x0e not yet handled', Driver=uvcvideo, 480M
$ 

---

这是USB带宽问题，不是VLC问题

VIDIOC\u STREAMON：设备上没有剩余空间

是USB带宽已满时给出的消息

大多数现代USB摄像头都能进行高速、高密度的图像输出。USB2限制为480Mbps，理论上为60兆字节/秒。实际上，所有类型的开销都将占用大约一半的开销，而30兆字节/秒是您可以获得的最大值。这意味着摄像机可以以每秒30帧的速度发送1兆字节的图像

所有你能做的就是得到多个USB总线主板。所有的小型计算机往往只有一台。高端游戏主板有2..3条USB2.0总线。您可以在linux下看到它：

$ lsusb -t
/:  Bus 04.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/4p, 5000M
/:  Bus 03.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/4p, 480M
    |__ Port 4: Dev 2, If 0, Class=scard, Driver=usbfs, 12M
/:  Bus 02.Port 1: Dev 1, Class=root_hub, Driver=ehci_hcd/2p, 480M
    |__ Port 1: Dev 2, If 0, Class=hub, Driver=hub/8p, 480M
        |__ Port 5: Dev 3, If 0, Class='bInterfaceClass 0xe0 not yet handled', Driver=btusb, 12M
        |__ Port 5: Dev 3, If 1, Class='bInterfaceClass 0xe0 not yet handled', Driver=btusb, 12M
/:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=ehci_hcd/2p, 480M
    |__ Port 1: Dev 2, If 0, Class=hub, Driver=hub/6p, 480M
        |__ Port 3: Dev 3, If 0, Class=vend., Driver=rts5139, 480M
        |__ Port 5: Dev 4, If 0, Class='bInterfaceClass 0x0e not yet handled', Driver=uvcvideo, 480M
        |__ Port 5: Dev 4, If 1, Class='bInterfaceClass 0x0e not yet handled', Driver=uvcvideo, 480M
$ 

很可能两个摄像头都连接到同一条总线上

---

另一种选择是降低FPS速度或分辨率。但这并不总是有帮助，因为我见过的相机保留了80%的USB带宽。

请参阅上面主要帖子底部的“更新7/24:”。它具有lsusb的结果-t此更新中只有一条USB2.0总线（寻找480Mbps总线。这是2.0。我如何在VMware fusion中再添加1条总线？我认为这是硬件，而不是VMware限制。额外的USB卡可能会有所帮助。硬件实际上非常强大。我在VMware上做事情之前对其进行了测试。这是一台Mac Pro计算机/工作站。早些时候，在Mac OS X上，我使用Mac端口安装了opencv（Python bindngs）我成功地用C++代码打开了2个相机。我也能用Python代码来做同样的事情。

$ lsusb -t
/:  Bus 02.Port 1: Dev 1, Class=root_hub, Driver=uhci_hcd/2p, 12M
    |__ Port 1: Dev 2, If 0, Class=HID, Driver=usbhid, 12M
    |__ Port 2: Dev 3, If 0, Class=hub, Driver=hub/7p, 12M
        |__ Port 1: Dev 4, If 0, Class='bInterfaceClass 0xe0 not yet handled', Driver=btusb, 12M
        |__ Port 1: Dev 4, If 1, Class='bInterfaceClass 0xe0 not yet handled', Driver=btusb, 12M
/:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=ehci_hcd/6p, 480M
    |__ Port 1: Dev 6, If 0, Class='bInterfaceClass 0x0e not yet handled', Driver=uvcvideo, 480M
    |__ Port 1: Dev 6, If 1, Class='bInterfaceClass 0x0e not yet handled', Driver=uvcvideo, 480M
    |__ Port 2: Dev 7, If 0, Class='bInterfaceClass 0x0e not yet handled', Driver=uvcvideo, 480M
    |__ Port 2: Dev 7, If 1, Class='bInterfaceClass 0x0e not yet handled', Driver=uvcvideo, 480M
$ 

$ lsusb -t
/:  Bus 04.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/4p, 5000M
/:  Bus 03.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/4p, 480M
    |__ Port 4: Dev 2, If 0, Class=scard, Driver=usbfs, 12M
/:  Bus 02.Port 1: Dev 1, Class=root_hub, Driver=ehci_hcd/2p, 480M
    |__ Port 1: Dev 2, If 0, Class=hub, Driver=hub/8p, 480M
        |__ Port 5: Dev 3, If 0, Class='bInterfaceClass 0xe0 not yet handled', Driver=btusb, 12M
        |__ Port 5: Dev 3, If 1, Class='bInterfaceClass 0xe0 not yet handled', Driver=btusb, 12M
/:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=ehci_hcd/2p, 480M
    |__ Port 1: Dev 2, If 0, Class=hub, Driver=hub/6p, 480M
        |__ Port 3: Dev 3, If 0, Class=vend., Driver=rts5139, 480M
        |__ Port 5: Dev 4, If 0, Class='bInterfaceClass 0x0e not yet handled', Driver=uvcvideo, 480M
        |__ Port 5: Dev 4, If 1, Class='bInterfaceClass 0x0e not yet handled', Driver=uvcvideo, 480M
$