Using gzdopen will not work properly if the C standard library used to
get the descriptor is not the same library as the one that was compiled
with zlib.  When this is the case, it causes zlib to fail to write a
file, and would report a C standard library error.  Use gzopen and
gzopen_w instead to ensure that the file is opened and closed by zlib
itself, ensuring that zlib and the libobs do not have to share the C
standard library between each other.

After some more testing, utvideo not only gives better encoding
performance, but also better compression and better decoding
performance.  It's pretty much superior all around over huffyuv.

So certain high-profile individuals were complaining that it was
difficult to configure recording settings for quality in OBS.  So, I
decided to add a very easy-to-use auto-configuration for high quality
encoding -- including lossless encoding.  This feature will
automatically configure ideal recording settings based upon a specified
quality level.

Recording quality presets added to simple output:

- Same as stream: Copies the encoded streaming data with no extra usage
  hit.

- High quality: uses a higher CRF value (starting at 23) if using x264.

- Indistinguishable quality: uses a low CRF value (starting at 16) if
  using x264.

- Lossless will spawn an FFmpeg output that uses huffyuv encoding.  If a
  user tries to select lossless, they will be warned both via a dialog
  prompt and a warning message in the settings window to ensure they
  understand that it requires tremendous amounts of free space.  It will
  always use the AVI file format.

Extra Notes:

- When High/Indistinguishable quality is set, it will allow you to
  select the recording encoder.  Currently, it just allows you to select
  x264 (at either veryfast or ultrafast).  Later on, it'll be useful to
  be able to set up pre-configured presets for hardware encoders once
  more are implemented and tested.

- I decided to allow the use of x264 at both veryfast or ultrafast
  presets.  The reasoning is two-fold:

  1.) ultrafast is perfectly viable even for near indistinguishable
quality as long as it has the appropriate CRF value.  It's nice if you
want to record but would like to or need to reduce the impact of
encoding on the CPU.  It will automatically compensate for the preset at
the cost of larger file size.

  2.) It was suggested to just always use ultrafast, but ultrafast
requires 2-4x as much disk space for the same CRF (most likely due to
x264 compensating for the preset).  Providing veryfast is important if
you really want to reduce file size and/or reduce blocking at lower
quality levels.

- When a recording preset is used, a secondary audio encoder is also
  spawned at 192 bitrate to ensure high quality audio.  I chose 192
  because that's the limit of the media foundation aac encoder on
  windows, which I want to make sure is used if available due to its
  high performance.

- The CRF calculation is based upon resolution, quality, and whether
  it's set to ultrafast.  First, quality sets the base CRF, 23 for
  "good" quality, 16 for "very high" quality.  If set to ultrafast,
  it'll subtract 2 points from the CRF value to help compensate.  Lower
  resolutions will also lower the CRF value to help improve higher
  details with a smaller pixel ratio.

Seems that most decoders that don't read the h264 header tend to expect
601 instead of 709.

For game capture, if a game is running at for example 800 FPS and limit
capture framerate is off, it would try to capture all 800 of those
frames, dramatically reducing performance more than what would ever be
necessary.

When limit capture framerate is off, instead of capturing all frames,
capture frames at an interval of twice the OBS FPS, identical to how
OBS1 works by default.  This should greatly increase performance under
that circumstance.

Use the actual parameter from the x264 params for CRF, and also make
sure to specify that CRF is meant to be 0 if CBR is enabled.

Sets the color range/space for FFmpeg output encoders that support it.

This also adds the ability to detect whether it stopped due to lack of
space or not -- particularly useful for the FFmpeg output due to
lossless file format support.

For the FFmpeg output, the encoder ids are sort of superfluous.  They
really should be optional.  If they're not set, it should use the
encoder name string instead to determine the ids automatically.

It seems that certain encoders (quicksync) do not have proper back-end
support in the windows media foundation libraries for certain CPUs.
Quicksync doesn't appear to support CPUs that are not haswell (4xxx) or
above.  It's really annoying, but there's not much we can do about it
until we implement our own custom quicksync implementation.

This check simply makes it attempt to spawn an encoder to check to see
whether the encoder can actually be created before registering an
encoder.

It's not impossible that this sort of thing could happen, although
unlikely.

The encoders were stopping before processing was completed, which could
cause the output to access data that's potentially invalidated.

The previous commit (672378d2) was supposed to fix issues with the
encoder releasing while data was still being processed, but did not
account for when the encoder has never started up.  That was my fault.

Furthermore, the way in which it was waiting to drain events was
incorrect.  The encoder may still be active even though there aren't any
events queued.  The proper way to wait for an async encoder to finish up
is to process output samples until it requests more input samples.

After I made it so that the encoder internal data gets destroyed when
all outputs stop using it (fa7286f8), the media foundation h264 encoder
started having crashes on shutdown.  After a lot of testing, I realized
that the reason it started happening is almost assuredly because active
encoding events had not yet been completed.

After making it wait on those events by calling DrainEvents(true), the
crashes stopped.  So asynchronous actions were clearly still occurring
and it was shutting down while data was still being processed, thus
leading to a crash.

Clean up Intensity Pro 4K commit a bit

Adds a VideoToolbox based H264 encoder for OSX, which most notably
allows the use of hardware encoding (Quicksync).

NOTES:
- Hardware encoding is handled by Apple itself internally.  The plugin
  itself has little control over many details due to the way that Apple
  designed the VideoToolbox interface.  Generally however, quicksync is
  used if available on the CPU, and quicksync is almost always available
  due to the fact that macs are exclusively Intel.

- The VideoToolbox does not seem to implement CBR, so it won't be
  available.  These encoders are generally not recommended for
  streaming.

Implements hardware encoders through the Media Foundation interface
provided by Microsoft.

Supports:
- Quicksync (Intel)
- VCE (AMD)
- NVENC (NVIDIA, might only be supported through MF on Windows 10)

Notes:
- NVENC and VCE do not appear to have proper CBR implementations.  This
  isn't a fault of our code, but the Media Foundation libraries.
  Quicksync however appears to be fine.

API changed from:
obs_source_info::get_name(void)
obs_output_info::get_name(void)
obs_encoder_info::get_name(void)
obs_service_info::get_name(void)

API changed to:
obs_source_info::get_name(void *type_data)
obs_output_info::get_name(void *type_data)
obs_encoder_info::get_name(void *type_data)
obs_service_info::get_name(void *type_data)

This allows the type data to be used when getting the name of the
object (useful for plugin wrappers primarily).

NOTE: Though a parameter was added, this is backward-compatible with
older plugins due to calling convention.  The new parameter will simply
be ignored by older plugins, and the stack (if used) will be cleaned up
by the caller.

The private type data is the type_data variable that's provided when
object types are registered by plugins.

This is useful for allowing the ability to have private data associated
with the object type definition structures.  This private data can be
useful for things like plugin wrappers for other languages, or providing
dynamically generated object types.

Selecting any supported FFmpeg format where ff_format_desc_extensions
returns NULL would crash the std::string constructor, so we pass an
empty extension instead (rtsp is one candidate format that triggers
the crash, on my machine at least)

This allows changing e.g. the number of segments in a hls playlist and
its caching behavior with:
"hls_allow_cache=1 hls_list_size=0"

This is used by some muxers that set AVFMT_NOFILE and doesn't seem to
hurt muxers that don't set it; notable this makes the hls muxer output
its m3u8 playlist with the proper filename in the proper directory

cleaning up my previous commit a bit. we can just keep the
appropriate BMDPixelFormat as a data member and keep StartCapture() a
bit clearer.

this might also be helpful if (when?) the detection code needs to be
more robust or configurable

Capture BMI Intensity Pro 4K video

detect the device type when initializing the device instance and
determine whether to capture YUV or RGB. tested with a Blackmagic
Intensity Pro and a Blackmagic Intensity Pro 4K in the same machine,
capturing at the same time, on Linux

This prevents encoders (hardware encoders in particular) from being
continually active when all outputs disconnect from an encoder.  This is
mostly just a temporary measure; the encoding interface may need a bit
of a redesign.  It will also definitely needs to be able to flush at
some point.  Currently when an output is stopped, the pending data is
discarded, which needs to be fixed.

Allows objects to be created regardless of whether the actual id exists
or not.  This is a precaution that preserves objects/settings if for
some reason the id was removed for whatever reason (plugin removed, or
hardware encoder that disappeared).  This was already added for sources,
but really needs to be added for other libobs objects as well: outputs,
encoders, services.

If the FFMPEG_AVCODEC_LIBRARIES variable does not exist, it will
generate a cmake error, so check to make sure the variable exists before
executing this code.

This fixes the compile error: "'AVDISCARD_NONINTRA' undeclared" when
using a libavcodec version earlier than 55.67.100.

Closes jp9000/obs-studio#469