SCC: caption management refactoring #395
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valnoel
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| # Captions being displayed | ||
| self.active_caption: Optional[SccCaptionParagraph] = None | ||
| # Caption style (Pop-on, Roll-up, Paint-on) currently processed | ||
| self.current_style = SccCaptionStyle.Unknown |
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Shouldn't we have a "default" style?
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What would be this default style? It seems a bit tricky to choose...
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I skimmed the 608 spec and couldn't find an obvious answer.
I would choose paint-on for now.
| # Buffered caption being built | ||
| self.buffered_caption = None | ||
| # Captions being displayed | ||
| self.active_caption: Optional[SccCaptionParagraph] = None |
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Shouldn't we start with a non-empty active caption, esp. if the default style is paint-on?
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I preferred to consider that nothing is displayed at start. And as the active caption is the caption being displayed, I choosed not the initialize it at start. That's why the "begin timecode" is set into the new_active_caption method.
Otherwise, we should initialize the active caption without "begin timecode", but it would mean that an active caption is ready but not currently displayed, which doesn't make sense for me.
What do you think?
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Shouldn't the begin time code be set when the first printable character is displayed, instead of when the caption is instantiated?
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The idea is to make the start of processing the same as the middle, i.e. there is always a front buffer and a back buffer active.
Maybe this is too much of a change for now. Let me know.
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Shouldn't the begin time code be set when the first printable character is displayed, instead of when the caption is instantiated?
This is done for Paint-On only. The begin time must be set on EOC for Pop-On, and on CR for Roll-Up.
The idea is to make the start of processing the same as the middle, i.e. there is always a front buffer and a back buffer active.
I understand the idea, but I think we cannot start writing into buffers without a minimum of context (a style at least), otherwise we're moving away from the spirit of the 608 specification...
But if it's a prerequisite, the change shouldn't be too big...
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608/708 are in fact streaming format (SCC added the timestamps) and a device could join the stream at any time and thus possibly in the middle of a caption.
What is the current behavior if we start parsing in the middle of a caption? A possible behavior is to do nothing until a style is specified -- is that what you have in mind? Maybe we should add this to the unit tests?
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@palemieux I've changed the reader behavior so that it skips captions until a style is specified in 49d14db
Let me know what you think!
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@atsampson @rktcc Your feedback would be welcome on this PR. |
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@atsampson @rktcc Did you have the opportunity to review? The plan is to merge this PR sometime next week. |
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Skip until a caption style is specified
Paragraphs have PopOn style and empty text line by default
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SCC reader refactoring proposal, addressing #383 & #385 issues