Crate v4l2r

source ·
Expand description

This library provides two levels of abstraction over V4L2:

  • The ioctl module provides direct, thin wrappers over the V4L2 ioctls with added safety. Note that “safety” here is in terms of memory safety: this layer won’t guard against passing invalid data that the ioctls will reject - it just makes sure that data passed from and to the kernel can be accessed safely. Since this is a 1:1 mapping over the V4L2 ioctls, working at this level is a bit laborious, although more comfortable than doing the same in C.

  • The device module (still WIP) provides a higher-level abstraction over the V4L2 entities, like device and queue. Strong typing will ensure that most inconsistencies while using the V4L2 API can be caught at compile-time.

These two layers should provide the foundations for higher-level libraries to provide safe, specialized APIs that support various V4L2 usage scenarios (camera, decoder/encoder, etc).

Modules§

  • controls
    Safe definitions around V4L2 extended controls.
  • decoder
    High-level interface for a V4L2 video decoder. Currently only supports the stateful interface.
  • device
    Interface to the V4L2 primitives that is both safe and higher-level than ioctl, while staying low-level enough to allow the implementation of any kind of V4L2 program on top of it.
  • encoder
    High-level interface for a V4L2 video encoder.
  • ioctl
    Provides safer versions of the V4L2 ioctls through simple functions working on a RawFd, and safer variants of the main V4L2 structures. This module can be used directly, but the device module is very likely to be a better fit for application code.
  • memory
    Abstracts the different kinds of backing memory (MMAP, USERPTR, DMABUF) supported by V4L2.

Structs§

  • Format
    Unified representation of a V4L2 format capable of handling both single and multi-planar formats. When the single-planar API is used, only one plane shall be used - attempts to have more will be rejected by the ioctl wrappers.
  • PixelFormat
    A Fourcc pixel format, used to pass formats to V4L2. It can be converted back and forth from a 32-bit integer, or a 4-bytes string.
  • PlaneLayout
    Description of a single plane in a format.
  • Rect
    A more elegant representation for v4l2_rect.

Enums§