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cta-wave / device-playback-task-force

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definition of fullscreen for 8.11 #75

Closed jpiesing closed 1 year ago

jpiesing commented 4 years ago

8.11 Full Screen Playback of Switching Sets 8.11.1 Background Fullscreen playback ensures that the device provide proper scaling and letter boxing. 8.11.2 Pre-conditions Same as documented in clause 8.9.2. Output is set to fullscreen.

8.11.5.2 Video If the track is a video track, then: • Every video frame S[k,s] shall be rendered such that it fills the entire video output window.

The video is specified to be 16:9. What if the aspect ratio of the display is not 16:9 (e.g. many? mobile devices), what is expected?

What if the display has overscan like some TVs still do?

TVs still sometimes (in some modes) support over-scan

jpiesing commented 4 years ago

You can see a lengthy discussion here about phone screen aspect ratios being 18:9 or even larger.

https://www.quora.com/What-are-the-advantages-and-disadvantages-of-18-9-ratio-screen-for-phones

It needs to be clear what the test would do on an 18:9 display phone and what would be a pass.

haudiobe commented 4 years ago

Would expect that if you 16:9 video, then it means no cropping of the video. You get black at the corners. You also keep square pixel. preserve aspect ratio, full video available, no cropping.

Document this observation. Should we also have none 16:9 content to test this experience?

4:3, 18:9, 21:9? Issue of new content, defer this.

jpiesing commented 1 year ago

Consider this "the video shall be scaled such that one side of the video fills the video/broadcast object fully without cropping the picture. The aspect ratio shall be preserved. Along the side where the video is shorter than the container, the video shall be centred. The area of the video plane not containing video shall be opaque black.".

"container" might not be the right word.

gitwjr commented 1 year ago

Implemented in v1.38 of spec. @jpiesing will add improved text.

jpiesing commented 1 year ago

Here is the revised proposal

"the video shall be scaled such that one side of the video fills the video output window fully without cropping the picture. The aspect ratio shall be preserved. Along the side where the video is shorter than the video output window, the video shall be centred. The area of the video plane not containing video shall be opaque black.".

i.e. the term "video output window" has been inserted which is widely used elsewhere in the spec.

gitwjr commented 1 year ago

@jpiesing If I read this correctly, the following text will replace item 2 in its entirety in 8.11.5.2 (i.e. deleting "i.e. If the output window aspect ratio is matching..." and "If the...is not matching...".

"Every video frame s[k,s] shall be rendered such that the video shall be scaled such that one side of the video fills the video output window fully without cropping the picture. The aspect ratio shall be preserved. Along the side where the video is shorter than the video output window, the video shall be centered. The area of the video plane not containing video shall be opaque black."

If this is the case I will make the edit to the spec along with the several others noted elsewhere.

gitwjr commented 1 year ago

Implemented in DPCTF v1.42.