FPS and TBR

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I've webm video file, which fps is 1k, and tbr 29.97

ffprobe video.webm
...
Stream #0:0: Video: vp9 (Profile 0), yuv420p(tv, progressive), 1280x720, SAR 1:1 DAR 16:9, 1k fps, 29.97 tbr, 1k tbn, 1k tbc (default)

OpenCV VideoCapture's property CAP_PROP_FPS is 1k, and CAP_PROP_FRAME_COUNT 123857. Real frame count when reading video is, however, 3712, so real fps is tbr: 1000 *(3712/123857) = 29.97

Is video file corrupted, or can I do something in OpenCV to get the real fps (and framecount without reading the whole video).