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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 showing:
# - How to setup the camera
# - Capture certain number of frames in a blocking manner
# - How to stop the camera
#
# This simple example is, in many ways, too simple. The purpose of the example
# is to introduce the concepts. A more realistic example is given in
# simple-continuous-capture.py.
import argparse
import libcamera as libcam
import selectors
import sys
# Number of frames to capture
TOTAL_FRAMES = 30
def main():
parser = argparse.ArgumentParser()
parser.add_argument('-c', '--camera', type=str, default='1',
help='Camera index number (starting from 1) or part of the name')
parser.add_argument('-f', '--format', type=str, help='Pixel format')
parser.add_argument('-s', '--size', type=str, help='Size ("WxH")')
args = parser.parse_args()
cm = libcam.CameraManager.singleton()
try:
if args.camera.isnumeric():
cam_idx = int(args.camera)
cam = next((cam for i, cam in enumerate(cm.cameras) if i + 1 == cam_idx))
else:
cam = next((cam for cam in cm.cameras if args.camera in cam.id))
except Exception:
print(f'Failed to find camera "{args.camera}"')
return -1
# 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)
if args.format:
fmt = libcam.PixelFormat(args.format)
stream_config.pixel_format = fmt
if args.size:
w, h = [int(v) for v in args.size.split('x')]
stream_config.size = libcam.Size(w, h)
ret = cam.configure(cam_config)
assert ret == 0
print(f'Capturing {TOTAL_FRAMES} frames with {stream_config}')
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))
# Create the requests and assign a buffer for each request
reqs = []
for i in range(num_bufs):
# Use the buffer index as the cookie
req = cam.create_request(i)
buffer = allocator.buffers(stream)[i]
ret = req.add_buffer(stream, buffer)
assert ret == 0
reqs.append(req)
# Start the camera
ret = cam.start()
assert ret == 0
# frames_queued and frames_done track the number of frames queued and done
frames_queued = 0
frames_done = 0
# Queue the requests to the camera
for req in reqs:
ret = cam.queue_request(req)
assert ret == 0
frames_queued += 1
# The main loop. Wait for the queued Requests to complete, process them,
# and re-queue them again.
sel = selectors.DefaultSelector()
sel.register(cm.event_fd, selectors.EVENT_READ)
while frames_done < TOTAL_FRAMES:
# cm.get_ready_requests() does not block, so we use a Selector to wait
# for a camera event. Here we should almost always get a single
# Request, but in some cases there could be multiple or none.
events = sel.select()
if not events:
continue
reqs = cm.get_ready_requests()
for req in reqs:
frames_done += 1
buffers = req.buffers
# A ready Request could contain multiple buffers if multiple streams
# were being used. Here we know we only have a single stream,
# and we use next(iter()) to get the first and only buffer.
assert len(buffers) == 1
stream, fb = next(iter(buffers.items()))
# Here we could process the received buffer. In this example we only
# print a few details below.
meta = fb.metadata
print("seq {:3}, bytes {}, frames queued/done {:3}/{:<3}"
.format(meta.sequence,
'/'.join([str(p.bytes_used) for p in meta.planes]),
frames_queued, frames_done))
# If we want to capture more frames we need to queue more Requests.
# We could create a totally new Request, but it is more efficient
# to reuse the existing one that we just received.
if frames_queued < TOTAL_FRAMES:
req.reuse()
cam.queue_request(req)
frames_queued += 1
# Stop the camera
ret = cam.stop()
assert ret == 0
# Release the camera
ret = cam.release()
assert ret == 0
return 0
if __name__ == '__main__':
sys.exit(main())
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