The virtual camera adds the ability to use the output of OBS itself as a
camera that can be selected within other Windows applications. This is
very loosely based upon the catxfish virtual camera plugin design.
There is a shared memory queue, but instead of having 10-20 frames in
the queue, there are now only 3 frames in the queue to minimize latency
and reduce memory usage. The third frame is mostly to ensure that
writing does not occur on the same frame being read; the delay is merely
one frame at all times.
The frames of the shared memory queue are NV12 instead of YUYV, which
reduces the memory and data copied, as well as eliminate unnecessary
conversion from NV12. Some programs (such as chrome, which uses webrtc
to capture) do not support NV12 however, so an I420 conversion is
provided, which is far less expensive than YUYV. The CPU cost of NV12
-> I420 is negligible in comparison.
The virtual camera filter itself is based upon the output filter within
the libdshowcapture library, which was originally implemented for other
purposes. This is more ideal than the Microsoft example code because
for one, it's far less convoluted, two, allows us to be able to
customize the filter to our needs a bit more easily, and three, has much
better RAII. The Microsoft CBaseFilter/etc code comprised of about 30
source files, where as the output filter comprises of two or three
required source files which we already had, so it's a huge win to
compile time.
Scaling is avoided whenever possible to minimize CPU usage. When the
virtual camera is activated in OBS, the width, height, and frame
interval are saved, that way if the filter is activated, it will always
remember the last OBS resolution/interval that the virtual camera was
activated with, even if OBS is not active. If for some reason the
filter activates before OBS starts up, and OBS starts up with a
different resolution, it will use simple point scaling intermittently,
and then will remember the new scaling in the future. The scaler could
use some optimization. FFmpeg was not opted for because the FFmpeg DLLs
would have to be provided for both architectures, which would be about
30 megabytes in total, and would make writing the plugin much more
painful. Thus a simple point scaling algorithm is used, and scaling is
avoided whenever possible.
(If another willing participant wants to have a go at improving the
scaling then go for it. But otherwise, it avoids scaling whenever
possible anyway, so it's not a huge deal)
The biHeight field can be negative, leading to crashes on some cards
like VisionRGB-E1S. Adding flip support is fairly straightforward.
There also appears to be a hack to automatically flip for RGB formats,
but I wish to remove it because it seems to fight with this change. We
already have a separate vertical flip checkbox to deal with non
compliant behavior.
This prevents VideoFormat::Any from unintentionally selecting H264 when
MJPEG is the only other format available.
This fixes a bug where certain devices (Logitech C920 with latest
drivers) will only have H264 and MJPEG available, and using
VideoFormat::Any will then select H264 over MJPEG because it's the first
format value and has the same priority as MJPEG. So now, MJPEG will be
prioritized over H264 instead.
Full color range seems to be active when decoding video with FFMmpeg
even when partial is explicitly selected. This should keep the range
synchronized.
Due to the recent change of using FFmpeg to decode MJPEG, MJPEG was
getting included in the delayed device check. This fixes that so that
it doesn't. MJPEG can decode in real time.
IsEncoded is meant to be used to indicated delayed devices, such as
older Elgato devices, or Hauppauge device. Devices that use H264 and
have a 800+ millisecond latency. This changes the function name to
better indicate that.
If a device produces video and audio timestamps atdifferent rates,
this divergence can cause massive buffering on the audio side, leading
to a capped audio buffer, and total sound loss. This change allows a
hardcoded list of devices to use the existing decoupling logic. For
now, only "GV-USB2" has been added.
When combined with another fix, 5+ hours of stable audio without any
buffering on my GV-USB2 where it used to drop sound completely after
an hour or so.
Partially fixes https://obsproject.com/mantis/view.php?id=1269
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.
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".
Allows the ability to override and use partial range RGB with the
DirectShow and Decklink device sources when partial range RGB is
implemented. Fixes certain cases where devices could capture RGB in
limited range via HDMI (per the HDMI specs).
MatcherClosestFrameRateSelector updates best_match as a side effect of
visiting every VideoInfo instance, but CapsMatch uses std::any_of,
which will stop iterating prematurely on first match. This means that
the highest FPS is not selected.
This change switches to a for loop that doesn't exit early.
Allows the ability to (optionally) synchronously create/update a
directshow device source rather than always asynchronously update the
device. This is useful if creating/destroying scenes/sources very
quickly, and helps minimize the risk of creating new directshow sources
that use the same device, yet may not activate because an existing
source may already exist. To use, set "synchronous_activate" to true in
its settings when updating or creating. Note that this setting will be
erased after it's used, and will not be saved to user settings, so it
must be set each time in order to be used.
Closesobsproject/obs-studio#1228
(also obs, deps/media-playback, libobs/audio-monitoring, decklink,
linux-alsa, linux-pulseaudio, mac-capture, obs-ffmpeg, win-dshow,
win-wasapi)
Default channel layout for 4 channels is 4.0 in FFmpeg.
Replacing quad with 4.0 will improve compatibility since FFmpeg has
better support of its default channel layouts.
Implement automatic audio device selection for devices that use two
separate DirectShow filters for audio and video instead of having a
single filter with audio and video output pins.
Please note that this fix is currently only active for Elgato USB and
PCIe devices (e.g. Cam Link, HD60 S, HD60 Pro, 4K60 Pro) to avoid
unintentionally changing the behavior for any other devices (e.g.
webcams).
(Jim edit: This fixes an issue with newer Elgato devices where the
devices would not automatically have their audio coupled with the video;
users would have to manually select the audio device in order to get
audio functioning.)
Closesjp9000/obs-studio#1081
jp9000
Clayton Groeneveld
Colin Edwards
Gol-D-Ace
jpark37
wanhongqing
Matt Gajownik
James Park
sorayuki
Richard Stanway
Kurt Kartaltepe
Ilya Melamed
pkviet
Thomas Schnitzler