mirror of
https://gitlab.freedesktop.org/gstreamer/gstreamer.git
synced 2024-11-26 19:51:11 +00:00
82 lines
1.9 KiB
Text
82 lines
1.9 KiB
Text
|
|
||
|
|
|
||
|
|
Problem #1:
|
||
|
|
|
||
|
|
How does the core allow the application to choose appropriate
|
||
|
|
caps in the following cases:
|
||
|
|
|
||
|
|
videotestsrc ! xvimagesink
|
||
|
|
|
||
|
|
videotestsrc ! identity ! xvimagesink
|
||
|
|
|
||
|
|
videotestsrc ! videoscale ! xvimagesink
|
||
|
|
|
||
|
|
Goals:
|
||
|
|
|
||
|
|
- Give the application a clear overview of the formats available
|
||
|
|
and the elements involved.
|
||
|
|
|
||
|
|
- Provide reasonable defaults in as many cases as possible.
|
||
|
|
|
||
|
|
- Allow specialized elements to suggest reasonable defaults.
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
Problem #2:
|
||
|
|
|
||
|
|
How does the API express to an autoplugger what an element does?
|
||
|
|
|
||
|
|
Currently, "colorspace" and "videoscale" have approximately the
|
||
|
|
same pad template caps. Until the autoplugger plugs and looks,
|
||
|
|
it has no way to determine that colorspace changes format, and
|
||
|
|
videoscale changes size.
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
Problem #3:
|
||
|
|
|
||
|
|
How do we properly handle codec metadata?
|
||
|
|
|
||
|
|
Solution #3a:
|
||
|
|
|
||
|
|
Stream initialization event. This event would be held by all
|
||
|
|
src pads, and pushed to sink pads upon connection, and would
|
||
|
|
flow downstream.
|
||
|
|
|
||
|
|
Solution #3b:
|
||
|
|
|
||
|
|
Put a buffer in the caps.
|
||
|
|
|
||
|
|
|
||
|
|
Problem #4:
|
||
|
|
|
||
|
|
(Related to #1) How does one specify that a converter should limit
|
||
|
|
it's conversion? I.e., audioconvert to not change number of channels,
|
||
|
|
or audioscale upsample by 20%. Basically, this means caps based on
|
||
|
|
other caps.
|
||
|
|
|
||
|
|
Solution #4a:
|
||
|
|
|
||
|
|
One can put a converter element into a special bin:
|
||
|
|
|
||
|
|
specialbin.( specialidentity ! converter ! specialidentity )
|
||
|
|
|
||
|
|
Specialbin can then interfere with caps negotiation all it wants.
|
||
|
|
|
||
|
|
|
||
|
|
Problem #5:
|
||
|
|
|
||
|
|
(Related to #3) How do we specify stream format information that
|
||
|
|
is non-critical and optional, such as pixel aspect ratio on raw
|
||
|
|
video?
|
||
|
|
|
||
|
|
Problem #6:
|
||
|
|
|
||
|
|
How do we specify the difference between nominal values and actual
|
||
|
|
values, such as video frame rate? The actual frame rate may not
|
||
|
|
correspond to the nominal frame rate in the caps, and often a guess
|
||
|
|
is listed.
|
||
|
|
|
||
|
|
|
||
|
|
|