Stingers -- and especially track matte stingers -- are currently subject
to real time decoding, which can be detrimental in a production
environment where a stinger video may not be able to decode in a timely
fashion.
To remedy this, this change adds an option to fully decode stingers
immediately and cache the decoded video/audio in RAM for playback to
greatly improve stinger performance.
Regular SDR/HDR stingers, and SDR track matte should work. HDR track
matte might work, but would take a carefully crafted video that takes
the SDR white level into account, and this hasn't been tested.
On Windows, All Files was added by default with (*), but on macOS and
Linux this appeared as an empty option in the dropdown and treated as a
Video Files filter rather than All Files.
This also adds proper translation handling for 'Video Files', matching
the obs-ffmpeg-source.
Fixes#5870
Color mismatch is apparent when using source transitions, which lerps
against transparent black and blends into the canvas nonlinearly. When
the transition is done, the blend switches to linear, leading to a pop.
Fix the issue by blending into the canvas in linear space. The lerp is
still nonlinear by design.
This adds the ability to use a secondary black-and-white video as a mask
between source A and B of the transition. The greyscale value of each
pixel is used as the "slider" value in a linear interpolation between the
corresponding pixels in source A and source B.
The track matte can either be in the same file as the stinger itself
(next to the stinger or under the stinger, doubling the width or height
of the stinger depending of the selected layout) or a in a separate
dedicated file.
The same file/separate file behavior is controlled by the
"Matte Layout" option in the stinger settings.
There are cases where alpha is multiplied unnecessarily. This change
attempts to use premultiplied alpha blending for composition.
To keep this change simple, The filter chain will continue to use
straight alpha. Otherwise, every source would need to modified to output
premultiplied, and every filter modified for premultiplied input.
"DrawAlphaDivide" shader techniques have been added to convert from
premultiplied alpha to straight alpha for final output. "DrawMatrix"
techniques ignore alpha, so they do not appear to need changing.
One remaining issue is that scale effects are set up here to use the
same shader logic for both scale filters (straight alpha - incorrectly),
and output composition (premultiplied alpha - correctly). A fix could be
made to add additional shaders for straight alpha, but the "real" fix
may be to eliminate the straight alpha path at some point.
For graphics, SrcBlendAlpha and DestBlendAlpha were both ONE, and could
combine together to form alpha values greater than one. This is not as
noticeable of a problem for UNORM targets because the channels are
clamped, but it will likely become a problem in more situations if FLOAT
targets are used.
This change switches DestBlendAlpha to INVSRCALPHA. The blending
behavior of stacked transparents is preserved without overflowing the
alpha channel.
obs-transitions: Use premultiplied alpha blend, and simplify shaders
because both inputs and outputs use premultiplied alpha now.
Fixes https://obsproject.com/mantis/view.php?id=1108
Add option in properties that let you choose how audio is mixed during
transition:
- Fade Out/Fade In (existing behavior, default)
- Crossfade
Closesjp9000/obs-studio#1028
