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81 lines
1.9 KiB
Text
81 lines
1.9 KiB
Text
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Problem #1:
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How does the core allow the application to choose appropriate
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caps in the following cases:
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videotestsrc ! xvimagesink
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videotestsrc ! identity ! xvimagesink
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videotestsrc ! videoscale ! xvimagesink
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Goals:
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- Give the application a clear overview of the formats available
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and the elements involved.
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- Provide reasonable defaults in as many cases as possible.
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- Allow specialized elements to suggest reasonable defaults.
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Problem #2:
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How does the API express to an autoplugger what an element does?
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Currently, "colorspace" and "videoscale" have approximately the
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same pad template caps. Until the autoplugger plugs and looks,
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it has no way to determine that colorspace changes format, and
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videoscale changes size.
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Problem #3:
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How do we properly handle codec metadata?
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Solution #3a:
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Stream initialization event. This event would be held by all
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src pads, and pushed to sink pads upon connection, and would
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flow downstream.
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Solution #3b:
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Put a buffer in the caps.
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Problem #4:
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(Related to #1) How does one specify that a converter should limit
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it's conversion? I.e., audioconvert to not change number of channels,
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or audioscale upsample by 20%. Basically, this means caps based on
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other caps.
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Solution #4a:
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One can put a converter element into a special bin:
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specialbin.( specialidentity ! converter ! specialidentity )
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Specialbin can then interfere with caps negotiation all it wants.
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Problem #5:
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(Related to #3) How do we specify stream format information that
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is non-critical and optional, such as pixel aspect ratio on raw
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video?
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Problem #6:
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How do we specify the difference between nominal values and actual
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values, such as video frame rate? The actual frame rate may not
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correspond to the nominal frame rate in the caps, and often a guess
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is listed.
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