src/py/examples/simple-continuous-capture.py


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#!/usr/bin/env python3

# SPDX-License-Identifier: BSD-3-Clause
# Copyright (C) 2022, Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>

# A simple capture example extending the simple-capture.py example:
# - Capture frames using events from multiple cameras
# - Listening events from stdin to exit the application
# - Memory mapping the frames and calculating CRC

import binascii
import libcamera as libcam
import libcamera.utils
import selectors
import sys


# A container class for our state per camera
class CameraCaptureContext:
    idx: int
    cam: libcam.Camera
    reqs: list[libcam.Request]
    mfbs: dict[libcam.FrameBuffer, libcamera.utils.MappedFrameBuffer]

    def __init__(self, cam, idx):
        self.idx = idx
        self.cam = cam

        # Acquire the camera for our use

        ret = cam.acquire()
        assert ret == 0

        # Configure the camera

        cam_config = cam.generate_configuration([libcam.StreamRole.Viewfinder])

        stream_config = cam_config.at(0)

        ret = cam.configure(cam_config)
        assert ret == 0

        stream = stream_config.stream

        # Allocate the buffers for capture

        allocator = libcam.FrameBufferAllocator(cam)
        ret = allocator.allocate(stream)
        assert ret > 0

        num_bufs = len(allocator.buffers(stream))

        print(f'cam{idx} ({cam.id}): capturing {num_bufs} buffers with {stream_config}')

        # Create the requests and assign a buffer for each request

        self.reqs = []
        self.mfbs = {}

        for i in range(num_bufs):
            # Use the buffer index as the "cookie"
            req = cam.create_request(idx)

            buffer = allocator.buffers(stream)[i]
            ret = req.add_buffer(stream, buffer)
            assert ret == 0

            self.reqs.append(req)

            # Save a mmapped buffer so we can calculate the CRC later
            self.mfbs[buffer] = libcamera.utils.MappedFrameBuffer(buffer).mmap()

    def uninit_camera(self):
        # Stop the camera

        ret = self.cam.stop()
        assert ret == 0

        # Release the camera

        ret = self.cam.release()
        assert ret == 0


# A container class for our state
class CaptureContext:
    cm: libcam.CameraManager
    camera_contexts: list[CameraCaptureContext] = []

    def handle_camera_event(self):
        # cm.get_ready_requests() returns the ready requests, which in our case
        # should almost always return a single Request, but in some cases there
        # could be multiple or none.

        reqs = self.cm.get_ready_requests()

        # Process the captured frames

        for req in reqs:
            self.handle_request(req)

        return True

    def handle_request(self, req: libcam.Request):