Video4Linux在开始拍摄时崩溃

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我尝试使用video4linux和mmap方法从网络摄像头捕获图像。我的设备是Gentoo Linux（内核版本2.6.33.20）上的Aptina MT9M114相机。该代码是基于这个示例程序：http://linuxtv.org/downloads/v4l-dvb-apis/capture-example.html Video4Linux在开始拍摄时崩溃

当我要开始captering，我运行下面的代码编写我的缓冲区：

enum v4l2_buf_type type; 

for (uint8_t i = 0; i < n_buffers; i++) { 
    struct v4l2_buffer buf; 
    CLEAR (buf); 
    buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; 
    buf.memory = V4L2_MEMORY_MMAP; 
    buf.index = i; 

    if (-1 == ioctl(fd, VIDIOC_QBUF, &buf)) { 
     return false; 
    } 
}

拨打电话时的ioctl（）在这里，我得到一个深层崩溃。这是我的日志，我没有更多的信息：

Mar 2 20:06:30 nao33 klogd: kernel BUG at drivers/media/video/videobuf-core.c:227! 
Mar 2 20:06:30 nao33 klogd: invalid opcode: 0000 [#2] PREEMPT 
... 
Mar 2 20:06:30 nao33 klogd: EIP: 0060:[<f804dad3>] EFLAGS: 00010246 CPU: 0 
Mar 2 20:06:30 nao33 klogd: EIP is at videobuf_qbuf+0x23f/0x32d [videobuf_core] 
Mar 2 20:06:30 nao33 klogd: EAX: 00000001 EBX: f5bf7e6c ECX: 00000000 EDX: f5bf7e6c 
Mar 2 20:06:30 nao33 klogd: ESI: f6bcf61c EDI: f657f140 EBP: f5bf7dc4 ESP: f5bf7db4 
Mar 2 20:06:30 nao33 klogd: DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 0068 preempt:00000000 
Mar 2 20:06:30 nao33 klogd: Process videoexample (pid: 2979, ti=f5bf6000 task=f5bf00b0 task.ti=f5bf6000) 
Mar 2 20:06:30 nao33 klogd: Stack: 
Mar 2 20:06:30 nao33 klogd: f5bf7e6c f5bf7e6c 00000000 f8255ca3 f5bf7dcc f8255cb0 f5bf7e48 f8148980 
Mar 2 20:06:30 nao33 klogd: <0> 0000ee34 00000001 c14a6e94 c044560f f6bcf600 f5bfb540 f825777c f6b18000 
Mar 2 20:06:30 nao33 klogd: <0> c14a6e94 f5bf7e10 c101ee52 00000000 f5bf00b0 f5bf7e20 c100160a f5bf0d80 
Mar 2 20:06:30 nao33 klogd: Call Trace: 
Mar 2 20:06:30 nao33 klogd: [<f8255ca3>] ? vidioc_qbuf+0x0/0xf [unicorn] 
Mar 2 20:06:30 nao33 klogd: [<f8255cb0>] ? vidioc_qbuf+0xd/0xf [unicorn] 
Mar 2 20:06:30 nao33 klogd: [<f8148980>] ? __video_do_ioctl+0xe00/0x2d31 [videodev] 
Mar 2 20:06:30 nao33 klogd: [<c101ee52>] ? set_next_entity+0xab/0x117 
Mar 2 20:06:30 nao33 klogd: [<c100160a>] ? __switch_to+0x12/0x14d 
Mar 2 20:06:30 nao33 klogd: [<c112dd83>] ? might_fault+0x14/0x16 
Mar 2 20:06:30 nao33 klogd: [<c112dedc>] ? _copy_from_user+0x31/0x115 
Mar 2 20:06:30 nao33 klogd: [<f814ab79>] ? video_ioctl2+0x2c8/0x368 [videodev] 
Mar 2 20:06:30 nao33 klogd: [<c104635f>] ? T.366+0x27/0x33 
Mar 2 20:06:30 nao33 klogd: [<f814a8b1>] ? video_ioctl2+0x0/0x368 [videodev] 
Mar 2 20:06:30 nao33 klogd: [<f814711c>] ? v4l2_ioctl+0x33/0x37 [videodev] 
Mar 2 20:06:30 nao33 klogd: [<c1085daf>] ? vfs_ioctl+0x69/0x91 
Mar 2 20:06:30 nao33 klogd: [<c10862ad>] ? do_vfs_ioctl+0x448/0x486 
Mar 2 20:06:30 nao33 klogd: [<c107c9dd>] ? fget_light+0x87/0x91 
Mar 2 20:06:30 nao33 klogd: [<c108632c>] ? sys_ioctl+0x41/0x61 
Mar 2 20:06:30 nao33 klogd: [<c1002790>] ? sysenter_do_call+0x12/0x26 
Mar 2 20:06:30 nao33 klogd: Code: 0f 8e e1 00 00 00 68 ba ec 04 f8 e9 77 fe ff ff 83 3d cc f4 04 f8 00 7e 0b 68 dc ec 04 f8 e8 13 e3 29 c9 5a 8b 4e 48 85 c9 75 04 <0f> 0b eb fe 83 f9 07 75 1d 83 7e 4c 02 75 0b c7 46 4c 03 00 00 
Mar 2 20:06:30 nao33 klogd: EIP: [<f804dad3>] videobuf_qbuf+0x23f/0x32d [videobuf_core] SS:ESP 0068:f5bf7db4

大家有一个提示，这里有什么问题吗？实际上，这个代码应该工作，因为它在我的本地PC上工作，并且主要是从这个例子中复制的。所以我不知道如何找到问题。

来源

2012-12-17 user1911083

该错误似乎与设置图像尺寸的过程有关。设置V4L2_FIELD_NONE而不是V4L2_FIELD_ANY解决了崩溃。

struct v4l2_format fmt; 
... 
fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; 
fmt.fmt.pix.width  = ... 
fmt.fmt.pix.height  = ... 
fmt.fmt.pix.pixelformat = ... 
fmt.fmt.pix.field  = V4L2_FIELD_NONE;

来源

2012-12-19 17:23:49 user1911083

Video4Linux在开始拍摄时崩溃

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