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Stated by Google's Camera Motion Metadata of VR180:

pts_of_this_metadata(t0) is the exposure start of the first used scanline in a video frame.

pixel_exposure_time_ns(t_pixel) is the exposure time for a single pixel in nanoseconds.

rolling_shutter_skew_time_ns(△t) is the delay between the exposure of the first-used scanline and the last-used scanline.

The PTS of the corresponding frame should be within t0 and t0 + △t + t_pixel.

Let t_line be the exposure time for a scanline (which is multiple t_pixel).

Why is t0 + △t + t_pixel, not t0 + △t + t_line?

It seams to me that t0 to t0 + △t + t_line express the whole frame exposure.

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Neil Z. Shao
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  • I think the formula from the [documentation](https://developers.google.com/streetview/publish/camm-spec#data-format) is the CAmera Motion Metadata (CAMM) spec which I think applied to all the 360 camera manufacturers. With that you have to comply with the specifications in the document in order to use the API with your camera. – Mr.Rebot Apr 23 '18 at 16:48
  • Yes. I'm trying to comply with the specs and in the meanwhile to understand them. So I'm wondering why is *the PTS within t0 + △t + t_pixel*, not t0 + △t + t_line? – Neil Z. Shao Apr 25 '18 at 05:27

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