For the show/hide and activate/deactivate callbacks, schedule these
callbacks to only be called from within the video thread rather than in
a separate thread.  This ensures that any potential graphics activity
that occurs within them is kept in the same thread.

When viewing the properties of a source, there's no way to specify that
a source is actually being shown or not to the core.  This uses the new
obs_source_inc_showing and obs_source_dec_showing to tell the source
that it's being shown/hidden in this part of the program without
necessarily having to use a new render view just to render it.

obs_source_inc_showing and obs_source_dec_showing are used to indicate
that a source is showing or no longer being shown in a particular area
of the program outside from the main render view.

One could use an obs_view, but I felt like it was unnecessary because
using an obs_view just to display a single source feels somewhat
superfluous.

This fixes a bug where sources would not decrement their showing
references when an obs_view is destroyed.

The main view does not need to worry about hiding/deactivation of
sources when it's being freed here, when the obs context is shutting
down in this section of obs, all the sources are being freed, thus
there's no need to worry about deactivating/hiding sources.

Fix bug 0000151: File loading not properly handled.

Link to bug: https://obsproject.com/mantis/view.php?id=151

A newly selected font is not loaded properly if "read from file" is
active without a valid file.  Old error handling lead to random memory
being displayed.

Closes Pull Request #390

(message edited by Jim)

By default, video plays back based upon the timestamp for each frame,
and buffers the frames as needed to ensure that they play back at the
expected timing.

However, this can add some minor additional delay to the video, and may
not be ideal for certain devices such as webcams and generally any
device that has minimal latency.  However, because those are the only
type of devices that typically have drivers, there's no real need to
have it on by default.

This adds an option to use buffering, and leaves it off by default.

Closes pull request #384

(message added by jim)

This optimizes the main OBSBasic.ui window so that it uses fewer objects
and thus fewer allocations.  Closes pull request #386

(message added by Jim)

linux-v4l2: Minor improvements

Use the macro from the mac capture plugin to convert the fourcc integer
value to a string. This makes the debug statement for the pixel format
slightly more readable for the casual developer.

Remove the "Leave Unchanged" option for the input and video format
select.

This option was primarily added for cases in which the
resolution and framerate are set by another program or the capture
device itself and the values are not directly supported by the plugin.
One major usecase here would be capture devices for tv signals which
might be set to a spcific resolution and refresh rate, and might fail
to initialize in case any other combination of those settings is forced.

In case of the input this option did not make much sense, as the first
input is probably the best default option in most cases.

For the video format this default is even bad in some cases. If an
format emulated by libv4l2 is selected for example, this will usually
configure the device to use mjpeg with libv4l2 converting it to some
format obs can use. When obs or the source is then restarted and the
"Leave Unchanged" is enabled the plugin will fail, because it will only
notice that the device is set to mjpeg, without any knowledge about the
possibility of letting libv4l2 handle the conversion.

Using the first available and supported format is not nescessarily the
best choice, but still preferable to some random format that will
cause the plugin to not capture at all. Forcing a choice here will
hopefully also make the plugin behaviour more predicatable for the user.

linux-v4l2: Fix string for translation

Changed "ImageFormat" for "VideoFormat"
(checked in v4l2-input.c)

linux-v4l2: Add support for dv timings

Use the dv timing selected in the source properties to configure the
device instead of resolution/framerate.

Add a helper function to set the dv timing for the input.

Show the dv timing property when the selected input supports it.

Add the dv timing property and hide it by default.

Add a helper function to enumerate dv timings supported by the
selected input and add them to a property.

Add a helper function to get a dv timing by index for the input.

View Log menu entry in Help -> Log Files menu

Since the file being logged to changes with each run, opening a log
file is a tad more involved than desirable when it's necessary to view
the log each time OBS is run. This new menu entry shortcuts opening the
file from the file system manually.

linux-v4l2: Add support for video standards

Use the video standard selected in the source properties to configure
the device instead of resolution/framerate.

Add a helper function to get/set the video standard for the input.

Use the capabilities for the selected input to decide which properties
are enumerated and displayed.

Add the video standard property and hide it by default.

Add a helper function to enumerate video standards supported by the
selected input and add them to a property.

Add a helper function to get the capabilities of a specific or the
currently selected input of the device.

Remove the constraint for device inputs to be of the type "CAMERA".
This was added under the false assumption that inputs of the type
"TUNER" are only used for control purposes.

Somehow managed to forget to add this function at an earlier point.
Allows the audio device to be changed via a simple update.

This allows the code to be used elsewhere as needed.

This was caused to do the new RTMP code that added support for multiple
streams; the stream index needs to be reset on RTMP_Close otherwise it
will keep using the wrong stream information.

UI: Fix rounding issues for advanced audio

Remove the close_float check for values that are set through the
advanced UI. If the difference of the integer was 1 this would sometimes
cause the input to be ignored.
Add rounding to values that are set through the signal system, since
casting alone will act like floor, which is not desirable in this case.

Previously having a source multiple times in a single scene would cause
the recursion check to trigger. Example scenes.json:

{
    "current_scene": "Scene",
    "sources": [
        {
            "flags": 0,
            "id": "scene",
            "mixers": 0,
            "name": "Scene",
            "settings": {
                "items": [
                    {
                        "align": 5,
                        "bounds": {
                            "x": 0.0,
                            "y": 0.0
                        },
                        "bounds_align": 0,
                        "bounds_type": 0,
                        "name": "Text (FreeType 2)",
                        "pos": {
                            "x": 0.0,
                            "y": 0.0
                        },
                        "rot": 0.0,
                        "scale": {
                            "x": 1.0,
                            "y": 1.0
                        },
                        "visible": true
                    },
                    {
                        "align": 5,
                        "bounds": {
                            "x": 0.0,
                            "y": 0.0
                        },
                        "bounds_align": 0,
                        "bounds_type": 0,
                        "name": "Text (FreeType 2)",
                        "pos": {
                            "x": 0.0,
                            "y": 98.0
                        },
                        "rot": 0.0,
                        "scale": {
                            "x": 1.0,
                            "y": 1.0
                        },
                        "visible": true
                    }
                ]
            },
            "sync": 0,
            "volume": 1.0
        },
        {
            "flags": 0,
            "id": "text_ft2_source",
            "mixers": 0,
            "name": "Text (FreeType 2)",
            "settings": {},
            "sync": 0,
            "volume": 1.0
        }
    ]
}

Previously a NULL item would cause a crash when reading transform info.
The crash can be reproduced by e.g. editing scenes.json so that two
scenes contain each other. Example scenes.json:

{
    "current_scene": "Scene",
    "sources": [
        {
            "flags": 0,
            "id": "scene",
            "mixers": 0,
            "name": "Scene",
            "settings": {
                "items": [
                    {
                        "align": 5,
                        "bounds": {
                            "x": 1440.0,
                            "y": 900.0
                        },
                        "bounds_align": 0,
                        "bounds_type": 2,
                        "name": "Scene 2",
                        "pos": {
                            "x": 0.0,
                            "y": 0.0
                        },
                        "rot": 0.0,
                        "scale": {
                            "x": 1.0,
                            "y": 1.0
                        },
                        "visible": true
                    }
                ]
            },
            "sync": 0,
            "volume": 1.0
        },
        {
            "flags": 0,
            "id": "scene",
            "mixers": 0,
            "name": "Scene 2",
            "settings": {
                "items": [
                    {
                        "align": 5,
                        "bounds": {
                            "x": 1.0,
                            "y": 1.0
                        },
                        "bounds_align": 0,
                        "bounds_type": 0,
                        "name": "Scene",
                        "pos": {
                            "x": 854.0,
                            "y": -520.0
                        },
                        "rot": 0.0,
                        "scale": {
                            "x": 1.75,
                            "y": 1.7562724351882935
                        },
                        "visible": true
                    }
                ]
            },
            "sync": 0,
            "volume": 1.0
        }
    ]
}