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https://github.com/opencv/opencv.git
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Mansour Moufid
a68e8d8289
Make cv::VideoCapture::get return cv::CAP_PROP_UNKNOWN (-1) for unsupported properties #21337 The return value indicating an unsupported property is not consistent across backends. I stumbled on this issue because my code was determining if a property value is valid if it's non-zero (like the documentation says), which worked fine on macOS, but not on Android. For example, auto-exposure is not supported on macOS, so get() returns 0. But it is supported on Android and 0 means auto-exposure is off. I think -1 is the better return value to indicate unsupported properties. I made changes to all the backends. I think I got every case. This breaks API compatibility for some backends, so I based this on branch 3.4. - [x] I agree to contribute to the project under Apache 2 License. - [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or other license that is incompatible with OpenCV - [x] The PR is proposed to proper branch - [ ] There is reference to original bug report and related work - [ ] There is accuracy test, performance test and test data in opencv_extra repository, if applicable Patch to opencv_extra has the same branch name. - [ ] The feature is well documented and sample code can be built with the project CMake
111 lines
3.9 KiB
Python
111 lines
3.9 KiB
Python
#!/usr/bin/env python
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from __future__ import print_function
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import numpy as np
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import cv2 as cv
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import io
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import sys
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import tempfile
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from tests_common import NewOpenCVTests
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class Bindings(NewOpenCVTests):
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def check_name(self, name):
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#print(name)
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self.assertFalse(name == None)
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self.assertFalse(name == "")
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def test_registry(self):
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self.check_name(cv.videoio_registry.getBackendName(cv.CAP_ANY));
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self.check_name(cv.videoio_registry.getBackendName(cv.CAP_FFMPEG))
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self.check_name(cv.videoio_registry.getBackendName(cv.CAP_OPENCV_MJPEG))
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backends = cv.videoio_registry.getBackends()
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for backend in backends:
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self.check_name(cv.videoio_registry.getBackendName(backend))
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def test_capture_stream_file(self):
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if sys.version_info[0] < 3:
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raise self.skipTest('Python 3.x required')
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api_pref = None
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for backend in cv.videoio_registry.getStreamBufferedBackends():
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if not cv.videoio_registry.hasBackend(backend):
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continue
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if not cv.videoio_registry.isBackendBuiltIn(backend):
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_, abi, api = cv.videoio_registry.getStreamBufferedBackendPluginVersion(backend)
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if (abi < 1 or (abi == 1 and api < 2)):
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continue
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api_pref = backend
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break
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if not api_pref:
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raise self.skipTest("No available backends")
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with open(self.find_file("cv/video/768x576.avi"), "rb") as f:
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cap = cv.VideoCapture(f, api_pref, [])
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self.assertTrue(cap.isOpened())
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self.assertEqual(cv.CAP_PROP_UNKNOWN, cap.get(-1))
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hasFrame, frame = cap.read()
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self.assertTrue(hasFrame)
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self.assertEqual(frame.shape, (576, 768, 3))
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def test_capture_stream_buffer(self):
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if sys.version_info[0] < 3:
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raise self.skipTest('Python 3.x required')
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api_pref = None
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for backend in cv.videoio_registry.getStreamBufferedBackends():
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if not cv.videoio_registry.hasBackend(backend):
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continue
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if not cv.videoio_registry.isBackendBuiltIn(backend):
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_, abi, api = cv.videoio_registry.getStreamBufferedBackendPluginVersion(backend)
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if (abi < 1 or (abi == 1 and api < 2)):
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continue
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api_pref = backend
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break
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if not api_pref:
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raise self.skipTest("No available backends")
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class BufferStream(io.BufferedIOBase):
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def __init__(self, filepath):
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self.f = open(filepath, "rb")
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def read(self, size=-1):
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return self.f.read(size)
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def seek(self, offset, whence):
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return self.f.seek(offset, whence)
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def __del__(self):
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self.f.close()
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stream = BufferStream(self.find_file("cv/video/768x576.avi"))
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cap = cv.VideoCapture(stream, api_pref, [])
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self.assertTrue(cap.isOpened())
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hasFrame, frame = cap.read()
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self.assertTrue(hasFrame)
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self.assertEqual(frame.shape, (576, 768, 3))
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def test_context_manager(self):
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video_file = self.find_file("cv/video/768x576.avi")
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with cv.VideoCapture(video_file) as cap:
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self.assertTrue(cap.isOpened(), "VideoCapture should be opened within context manager")
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with tempfile.NamedTemporaryFile(suffix='.avi') as tmp:
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with cv.VideoWriter(tmp.name, cv.VideoWriter_fourcc(*'MJPG'), 25, (640, 480)) as writer:
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self.assertTrue(isinstance(writer, cv.VideoWriter))
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try:
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with cv.VideoCapture(video_file) as cap:
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self.assertTrue(cap.isOpened())
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raise RuntimeError("Testing context manager exception safety")
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except RuntimeError:
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pass
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if __name__ == '__main__':
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NewOpenCVTests.bootstrap()
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