Add function that tries to reset v4l2loopback output for module versions
from 0.12.5 to 0.12.7. If successful, then set flag that STREAMON and
STREAMOFF are necessary each time the device is opened/closed.
These days you might capture card a 175Hz monitor with a framerate
defined as 10000000/57143 that doesnt fit in a short. And reporting a
negative FPS in that case isnt very helpful.
Effectively reverting parts of d314d47, this commit removes the new
functions that got added to remove the flags parameter. Instead, it just
marks the parameter as unused and documents this. Having what is
effectively an API break just to remove a parameter is a bit overkill.
The other parts of d314d47 which cleaned up the usage of the flags
parameter are untouched here.
This deprecates the following functions, replacing them with new
versions:
- `obs_output_can_begin_data_capture()` - now `*capture2()`
- `obs_output_initialize_encoders()` - now `*encoders2()`
- `obs_output_begin_data_capture()` - now `*capture2()`
The flags parameter was initially designed to support audio-only or
video-only operation of an output which had the `OBS_OUTPUT_AV` flag,
however, full support for that was never implemented, and there are
likely fundamental issues with an implementation, mainly that most
outputs are programmed assuming that there will always be at least one
audio and one video track. This requires new flags specifying support
for optional audio/video, among other things.
An implementation to allow audio/video to be optional is best done
using the flag technique above, with audio/video enablement specified
by whether media (raw, `video_t/audio_t`) or encoder (`obs_encoder_t`)
objects are specified.
Since every implementation I could find always specifies `flags` as 0,
I was able to safely conclude that immediately removing the parameter's
functionality is safe to do.
Parentheses are needed due to operator precedence (although the previous
code happened to work because POLLIN has the value 1).
Fixes: 91f986ec99 ("linux-v4l2: Check udev fd events")
udev_event_thread calls poll with two fds: the udev fd, and an eventfd
used for shutdown. On FreeBSD we were hanging on shutdown in
udev_monitor_receive_device after receiving the eventfd event.
Now, if the udev fd reports no events skip the
udev_monitor_receive_device call.
At shutdown the loop will exit via os_event_try().
Currently we use signals based on os_event's but the udev code blocks in
a 1s select (now poll) that cannot be signalled without an FD. This adds
an extra eventfd which will be signalled along with the os_event to
trigger the poll.
Also switches from select to poll to avoid issues with large fd values.
Status output related to OBS configuration is prefixed with the string
"OBS" and added padding for enabled and disabled features. This padding
was not aligned between platforms.
By moving the padding and prefix decoration into its own function,
both elements are controlled in a single place. CMake scripts were
changed to use this new function `obs_status` instead of using CMake's
`message` function directly.
