https://github.com/raspberrypi/py-videodev2
https://github.com/raspberrypi/py-videodev2
Last synced: 8 months ago
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- Host: GitHub
- URL: https://github.com/raspberrypi/py-videodev2
- Owner: raspberrypi
- Created: 2025-07-03T09:31:16.000Z (9 months ago)
- Default Branch: main
- Last Pushed: 2025-07-22T08:10:29.000Z (8 months ago)
- Last Synced: 2025-07-22T13:52:05.533Z (8 months ago)
- Language: Python
- Size: 33.2 KB
- Stars: 1
- Watchers: 0
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
# py-videodev2
A Python script that automatically converts Video4Linux2 (V4L2) C header files to Python ctypes bindings.
## Overview
This tool parses the Linux `videodev2.h` header file and generates clean, Pythonic ctypes bindings for the V4L2 API. It handles complex C constructs like inline unions, enums, structs, and preprocessor definitions, producing ready-to-use Python code.
## Requirements
- Python 3.6+
- `clang` preprocessor (for header preprocessing)
- Linux kernel headers (for complete V4L2 definitions)
## Usage
### Basic Usage
```bash
./convert-videodev2.py /usr/include/linux/videodev2.h -o videodev2.py
```
### With Custom Defines
```bash
./convert-videodev2.py videodev2.h -D CUSTOM_DEFINE -D ANOTHER_DEFINE -o output.py
```
### With Custom Clang Binary
```bash
./convert-videodev2.py videodev2.h --bin /usr/bin/clang-15 -o output.py
```
### Command Line Options
- `input_file`: Path to the videodev2.h header file
- `-o, --output`: Output Python file (default: `videodev2.py`)
- `-D, --define`: Add preprocessor defines (default: `__aarch64__`, `__KERNEL__`, `__arch64__`)
- `--bin`: Path to clang binary (default: `clang`)
**Note**: The script includes `__aarch64__`, `__KERNEL__`, and `__arch64__` as default defines to ensure compatibility with ARM64 systems and enable kernel-specific definitions.
## Generated Code Structure
The generated Python module includes:
### Enums with Global Constants
```python
class v4l2_field(IntEnum):
V4L2_FIELD_ANY = 0
V4L2_FIELD_NONE = 1
V4L2_FIELD_TOP = 2
# Global constants for compatibility
V4L2_FIELD_ANY = v4l2_field.V4L2_FIELD_ANY
V4L2_FIELD_NONE = v4l2_field.V4L2_FIELD_NONE
```
### Structures with Nested Unions
```python
class v4l2_plane(Structure):
class _u(Union):
_fields_ = [
('mem_offset', c_uint32),
('userptr', c_ulong),
('fd', c_int32)
]
_fields_ = [
('bytesused', c_uint32),
('length', c_uint32),
('m', _u),
('data_offset', c_uint32),
('reserved', c_uint32 * 11)
]
```
### IOCTL Definitions
```python
VIDIOC_QUERYCAP = _IOR('V', 0, v4l2_capability)
VIDIOC_G_FMT = _IOWR('V', 4, v4l2_format)
```
### Helper Functions
```python
def v4l2_fourcc(a, b, c, d):
"""Create a FOURCC value from four characters"""
return (ord(a) | (ord(b) << 8) | (ord(c) << 16) | (ord(d) << 24))
```
## Example Usage of Generated Code
```python
import videodev2 as v4l2
import fcntl
# Open video device
fd = open('/dev/video0', 'rb+', buffering=0)
# Query capabilities
cap = v4l2.v4l2_capability()
fcntl.ioctl(fd, v4l2.VIDIOC_QUERYCAP, cap)
print(f"Driver: {cap.driver.decode()}")
print(f"Card: {cap.card.decode()}")
# Set format
fmt = v4l2.v4l2_format()
fmt.type = v4l2.V4L2_BUF_TYPE_VIDEO_CAPTURE
fmt.fmt.pix.width = 640
fmt.fmt.pix.height = 480
fmt.fmt.pix.pixelformat = v4l2.v4l2_fourcc('Y', 'U', 'Y', 'V')
fcntl.ioctl(fd, v4l2.VIDIOC_S_FMT, fmt)
```
## License
This project is licensed under the BSD 3-Clause License. See the script header for full license text.