RGB to YUV converison was previously baked into every scale shader, but
this work has been moved to the YUV packing shaders. The scale shaders
now write RGBA instead. In the case where base and output resolutions
are identical, the render texture is forwarded directly to the YUV pack
step, skipping an entire fullscreen pass.
Intel GPA, SetStablePowerState, Intel HD Graphics 530, NV12
1920x1080, Before:
RGBA -> UYVX: ~321 us
UYVX -> Y: ~480 us
UYVX -> UV: ~127 us
1920x1080, After:
[forward render texture]
RGBA -> Y: ~487 us
RGBA -> UV: ~131 us
1920x1080 -> 1280x720, Before:
RGBA -> UYVX: ~268 us
UYVX -> Y: ~209 us
UYVX -> UV: ~57 us
1920x1080 -> 1280x720, After:
RGBA -> RGBA (rescale): ~268 us
RGBA -> Y: ~210 us
RGBA -> UV: ~58 us
There are devices like the GV-USB2 that produce frames with smmoth
timestamps at an uneven pace, which causes OBS to stutter because the
unbuffered path is designed to aggressively operate on the latest frame.
We can make the unbuffered path work by making two adjustments:
- Don't discard the current frame until it has elapsed.
- Don't skip frames in the queue until they have elapsed.
The buffered path still has problems with deinterlacing GV-USB2 output,
but the unbuffered path is better anyway.
Testing:
GV-USB2, Unbuffered: Stuttering is gone!
GV-USB2, Buffered: No regression (still broken).
SC-512N1-L/DVI, Unbuffered: No regression (still works).
SC-512N1-L/DVI, Buffered: No regression (still works).
It's a waste of GPU time to do two fullscreen passes to render final mix
previews. Use blend states to simulate the black background of
DrawBackdrop() for the following situations:
- Main preview window (Studio Mode off)
- Studio Mode: Program
This does not effect:
- Studio Mode: Preview (still uses DrawBackdrop)
- Fullscreen Projector (uses GPU clear to black)
- Windowed Projector (uses GPU clear to black)
intel GPA, SetStablePowerState, Intel HD Graphics 530, 1920x1080
Before:
DrawBackdrop: ~529 us
main texture: ~367 us (Cheaper than drawing a black quad?)
After:
[DrawBackdrop optimized away]
main texture: ~383 us
As the names entered into this dialog can be used as part of file names
(for example, saving a scene collection), allowing long names can result
in silent data loss where OBS creates the collection and allows the user
to manipulate it, but it cannot be saved on exit. This is due to the
MAX_PATH limitation on Windows (260 characters). 170 was chosen to
accomodate the length of the user app data folder plus some room for
extensions like .json.tmp.
Add a separate shader for area upscaling to take advantage of bilinear
filtering. Iterating over texels is unnecessary in the upscale case
because a target pixel can only overlap 1 or 2 texels in X and Y
directions. When only overlapping one texel, adjust UVs to sample texel
center to avoid filtering.
Also add "base_dimension" uniform to avoid unnecessary division.
Intel HD Graphics 530, 644x478 -> 1323x1080: ~836 us -> ~232 us
glGetError() returns GL_INVALID_OPERATION during OBS shutdown when GL is
used on Windows. This change gives up after eight errors.
This could be avoided by stopping the graphics thread before window
destruction, but the shutdown code looks like it could be tricky to
reorder.
