Class V4l2Backend

rustcv-camera/src/backend/linux/mod.rs:65–95

V4L2 capture backend using direct ioctl calls and mmap buffers. 使用直接 ioctl 调用和 mmap 缓冲区的 V4L2 采集后端。

/// V4L2 capture backend using direct ioctl calls and mmap buffers.
/// 使用直接 ioctl 调用和 mmap 缓冲区的 V4L2 采集后端。
pub(crate) struct V4l2Backend {
    /// File descriptor for the opened /dev/videoN device.
    /// 已打开的 /dev/videoN 设备的文件描述符。
    fd: RawFd,

    /// Memory-mapped buffers. Index matches V4L2 buffer index.
    /// 内存映射缓冲区。索引与 V4L2 缓冲区索引对应。
    buffers: Vec<MmapBuffer>,

    /// Index of the currently dequeued buffer (held by user via Frame<'a>).
    /// `None` if no buffer is currently held.
    /// 当前被出队的缓冲区索引（由用户通过 Frame<'a> 持有）。
    /// 如果没有缓冲区被持有则为 `None`。
    pending_queue: Option<usize>,

    /// Negotiated image width in pixels.
    /// 协商后的图像宽度（像素）。
    width: u32,

    /// Negotiated image height in pixels.
    /// 协商后的图像高度（像素）。
    height: u32,

    /// Negotiated pixel format.
    /// 协商后的像素格式。
    pixel_format: PixelFormat,

    /// Whether streaming is currently active.
    /// 流是否正在运行。
    streaming: bool,
}

impl V4l2Backend {
    /// Create a new (uninitialized) V4L2 backend.