log ffmpeg command line & export interpolation to VOC

[jrjbertram]

Add ffmpeg command line to logs for easier debuggging of frame extraction issues in the future.

Edit: Also included a change to the convert.py script to support interpolated annotation for video files.

Related to issue #275

[nmanovic]

@jrjbertram , thanks for your contribution! Could you please help us to improve the PR a little bit? Need to remove extra blank lines and fix coday issues.

[nmanovic]

@jrjbertram , one more ask. Could you please add some information about the contribution into CHANGELOG.md file?

[nmanovic]

@jrjbertram ,

One more problem, need to adjust tests for the converter. Inside virtual environment with all necessary dependencies just run python manage.py test utils and you will see the output below. Just need to adjust the file: utils/voc/tests/test_process_cvat_xml.py

Creating test database for alias 'default'...
System check identified no issues (0 silenced).
.0
    1: (626.810000,30.960000) (656.050000,58.880000) 'car'
1
    1: (626.630000,31.560000) (655.870000,59.480000) 'car'
2
110
    0: (634.120000,37.680000) (661.500000,71.370000) 'car'
111
    0: (634.210000,38.500000) (661.590000,72.190000) 'car'
112
F
======================================================================
FAIL: test_parse_interpolation_xml (utils.voc.tests.test_process_cvat_xml.TestProcessCvatXml)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/usr/lib/python3.6/unittest/mock.py", line 1179, in patched
    return func(*args, **keywargs)
  File "/workspace/cvat_github/utils/voc/tests/test_process_cvat_xml.py", line 169, in test_parse_interpolation_xml
    self.assertTrue(len(os.listdir(voc_dir)) == 0)
AssertionError: False is not true

----------------------------------------------------------------------
Ran 2 tests in 0.082s

FAILED (failures=1)
Destroying test database for alias 'default'...

[jrjbertram]

I tried reproducing the test failure but was unable to. Will work on that.

[jrjbertram]

Got it worked out. I misunderstood the testing environment, but figured it out from CONTRIBUTING.md. Tests should be passing now. All other findings should now be addressed as well.

[nmanovic]

@jrjbertram , thanks for your patience. I know that it is hard to implement something for a new project. I appreciate your time and willing to help.

[jrjbertram]

@nmanovic no worries at all. Thanks for catching the bugs.