Filters can be hidden without being shown, which can unbalance the ref
count and destroys them prematurely. We really only care about input
sources having a chance to clean up from the render thread from the hide
handler, Windows 10 window capture specifically.

This provides a chance to clean up resources on the graphics thread in
the hide callback, which Windows Graphics Capture requires.

Allows the ability for manual transitioning to smoothly flow
(interpolate) to the intended transition point over a short period of
time rather than simply setting a hard transition point number.  Doing
this allows manual transitioning to occur more smoothly, and in a more
visually pleasant way.

Closes obsproject/obs-studio#2224

Export obs_group_from_source to allow it to be used externally

Allows the ability to change the behavior of a source depending on the
previous OBS version.

Adds functions to allow sources to inform the UI whether the audio is
currently active or not.  Allows the ability to turn on/off the items in
the mixer.

If for whatever reason the format is swapped between BGRA/BGRX in an
async filter, swap the texture to compensate for that.  This allows
plugins to change the format if necessary.

Originally when the audio_submix function was created, it used all mixer
tracks, but at a certain point that was removed because it can only use
the first track, so some older code was unintentionally left over,
causing the same code to be executed 6 times mistakenly.  This cleans
that up by removing the unnecessary function parameter and for loop.

This fixes a race condition where the audio/video backends/threads may
start using sources before their obs_source_info::create function has
been called.

This function is not used outside of the source file, so make it static.

When a source type has been removed (i.e. its plugin has been removed)
info can be null, which is permitted.

Adds the "audio_line" internal source type as a bare source type for the
sole purpose of outputting audio, and the obs_source_info::audio_mix
callback which allows mixing of those audio lines, which is then treated
as normal audio for the source.  Audio line objects should be added as
sub-sources when multiple audio lines from a single source are needed,
then mixed together with the audio_mix callback.

The difference between the new obs_source_info::audio_mix callback and
obs_source_info::audio_render is that obs_source_info::audio_mix (along
with the audio_line source) are only one track, and it outputs audio to
the source automatically via obs_source_output_audio() when the call
completes.  This allows the mixed audio to be treated like a normal
source's audio, in that you can filter it, change its volume, or monitor
it.

This change was necessary because the CEF (used with the browser source)
outputs multiple audio streams at once to a single browser source, so
it's the program's responsibility to mix those streams together itself.

This will allow YUV alpha formats to be converted to RGBA on the GPU.

The shaders to unpack YUV information from the same texture were rather
complicated. Breaking them up into separate textures makes the shaders
much simpler, and we can remove the PRECISION_OFFSET hack.

Performance also gets a nice boost on Intel for planar textures.

Intel GPA, SetStablePowerState, Intel HD Graphics 530, 1920x1080

UYVY: 473 us -> 457 us
YUY2: 492 us -> 422 us
YVYU: 491 us -> 441 us
I420: 1637 us -> 505 us
I422: 1644 us -> 482 us
I444: 1653 us -> 504 us
NV12: 1656 us -> 369 us
Y800 (limited): 270 us -> 277 us
Y800 (full): 263 us -> 289 us
RGB (limited): 341 us -> 411 us
BGR3 (limited): 512 us -> 509 us
BGR3 (full): 527 us -> 534 us

The video format is not updated if switching between cache-compatible
formats, e.g. YUY2 and YVYU, resulting in the wrong conversion technique
being used. This change ensures the format is always up-to-date.

This format has been seen when using FFmpeg MJPEG decompression.

Unlike get_properties, there is not reason to not call get_defaults if it is
given in addition to get_defaults2. Additonally this fixes the bug with
'init_encoder' which would only ever call get_defaults, resulting in broken
encoders if those used get_defaults2.

If an audio source does not provide enough data at a steady pace, the
timestamp update does not happen, and buffering increases until it
maxes out. To counteract this, update the timestamp anyway.

Another issue for decoupled audio sources is that timing is not
adjusted for divergence from system time. Making this adjustment is
better for timing stability.

5+ hours of stable audio without any buffering on my GV-USB2 where it
used to add 21ms every 5 mintues or so.

Fixes https://obsproject.com/mantis/view.php?id=1269

Fix ternary test to use BGRX render targets for YUV to RGB
conversions. The previous behavior may have been fine though since
the shaders fill the alpha channel with 1.0 anyway.

Code submissions have continually suffered from formatting
inconsistencies that constantly have to be addressed.  Using
clang-format simplifies this by making code formatting more consistent,
and allows automation of the code formatting so that maintainers can
focus more on the code itself instead of code formatting.

The cache coherency of rasterization for full-screen passes is better
using an oversized triangle that is clipped rather than two triangles.
Traversal order of rasterization is GPU-specific, but will almost
certainly be better using an undivided primitive.

A smaller benefit is that quads along the diagonal are not evaluated
multiple times, but that's minor in comparison.

Redo format shaders to bypass vertex buffer, and input layout. Add
global shader bool "obs_glsl_compile" to make API-specific decisions,
i.e. handle upside-down UVs. gl_ortho is not needed for format
conversion because the vertex shader does not use ViewProj anymore.

This can be applied to more situations, but start small first.

Testbed full screen passes, Intel HD Graphics 530:
RGBA -> UYVX: 467 -> 439 us, ~6% savings
UYVX -> uv: 295 -> 239 us, ~19% savings

This fixes the issue where limited-range RGB sources were being
composited with dirty render targets.

Someone mentioned this format preserves the most quality for a
particular capture card using V4L2.

A previous refactoring to make DrawMatrix unnecessary has left behind
unreachable YUV conversions. Even if this code was somehow reachable,
DrawMatrix for YUV -> RGB doesn't exist anymore, so they would render
incorrectly anyway.

This commit adds a function to forcefully stop a transition, and to
increment/decrement the showing counter for a source with the MAIN_VIEW
type.

These functions are needed for the transition previews to work as
intended.

Clang doesn't like it if you convert T** to const T* const* without
casting even though it should be safe. Might be a C language thing.

libobs: Add support for limited to full color range conversions when
using RGB or Y800 formats, and move RGB converison for Y800 formats to
the GPU.

decklink: Stop hiding color space/range properties for RGB formats, and
remove "YUV" from "YUV Color Space" and "YUV Color Range".

win-dshow: Remove "YUV" from "YUV Color Space" and "YUV Color Range".

UI: Remove "YUV" from "YUV Color Space" and "YUV Color Range".

Fixes handling of the `obs_source_frame::full_range` member variable,
which is often set to false by default by many plugins even when using
RGB, which would cause RGB to be marked as "partial range".  This change
is crucial for when partial range RBG support is implemented.

Adds `obs_source_frame2` structure that replaces the `full_range` member
variable with a `range` variable, which uses the `video_range_type` enum
to allow handling default range values.  This member variable treats
VIDEO_RANGE_DEFAULT as full range if the format is RGB, and partial
range if the format is YUV.

Also adds `obs_source_output_video2` and `obs_source_preload_video2`
functions which use the `obs_source_frame2` structure instead of the
`obs_source_frame` structure.

When using the original `obs_source_frame`, `obs_source_output_video`,
and `obs_source_preload_video` functions, RGB will always be full range
by default for backward compatibility purposes.

This reverts commit d91bd327, which
broke alpha with sources, scenes, and filter, causing them all to become
opaque unintentionally.

Currently several shaders need "DrawMatrix" techniques to support the
possibility that the input texture is a "YUV" format. Also, "DrawMatrix"
is overloaded for translation in both directions when it is written for
RGB to "YUV" only.

A cleaner solution is to handle "YUV" to RGB up-front as part of format
conversion, and ensure only RGB inputs reach the other shaders. This is
necessary to someday perform correct scale filtering without the cost of
redundant "YUV" conversions per texture tap.

A necessary prerequisite for this is to add conversion support for
VIDEO_FORMAT_I444, and that is now in place. There was already a hack in
place to cover VIDEO_FORMAT_Y800. All other "YUV" formats already have
conversion functions.

"DrawMatrix" has been removed from shaders that only supported "YUV" to
RGB conversions. It still exists in shaders that perform RGB to "YUV"
conversions, and the implementations have been sanitized accordingly.

Add D3D/GL debug markers to make RenderDoc captures easier to tranverse.

Also add obs_source_get_name_no_null() to avoid boilerplate for safe
string formatting.

Closes obsproject/obs-studio#1799

Currently SrcBlendAlpha and DestBlendAlpha are both ONE, and can
combine together to form two. This is not a noticeable problem for
UNORM targets because the channels are clamped, but it will likely
become a problem if FLOAT targets are more widely used.

This change switches DestBlendAlpha to INVSRCALPHA, and starts
backgrounds as opaque black instead of transparent black. The blending
behavior of stacked transparents is preserved without overflowing the
alpha channel.

If audio monitoring is enabled and set to output only, the
obs_source_show_preloaded_video function would still incorrectly set the
current source audio output timestamp to the current system time, which
would cause audio to use an incorrect starting point from long ago for
the first starting audio segment if audio monitoring is then turned off
some time after having started the source.

Instead, the starting timestamp should be set to 0 if audio monitoring
is enabled with no output to stream, so that if/when audio monitoring is
disabled, it recalculates the starting timestamp of the first audio
packet on the spot again.

Closes obsproject/obs-studio#1522