Updated FFmpeg, Decklink drivers 14.3 compatibility

• Updated FFmpeg to version 7.1
• Fixes to restore Blackmagic Desktop Video drivers compatibility (tested on 14.3 and 14.4)

New channel layout: dual-stereo, fixes

New audio channel layout is declared, dual-stereo, for two audio versions. Many fixes (see commit log).

Nvidia Quadro GPU selection

It's now possible to run CasparCG using selected Nvidia Quadro GPU. There is new setting gpu-index in mixer section of casparcg.config to select right one.
The feature work when using RDP or any other case when the card is not connected to display (e.g. server uses its built-in card).
This is available only Nvidia GPUs, it works with Quadro GPUs, don't work with GeForce, should work with Tesla accelerators and in Windows cloud environments providing OpenGL acceleration.
This feature provides that Windows should not consume GPU performance, i.e. when user is logging on.

Added tray icon

...and:

• minimize to tray
• new HIDE console command
• tray icon double click --> restore window
• tray icon right mouse click -> simple menu

Improved scaling

This release uses FFmpeg scale filter instead of OpenGL scaling for video clips. Also, when up-scaling interlaced clip, the clip is deintrlaced using bwdif filter doubling its frame rate, then scaled, and reinterlaced using FFmpeg filters.
This adresses #1 and bring significant quality improvement, especially when up-scaling SD to HD content.
All this requires more CPU power, and may require more PCI throughput.

Fix for Windows 10

This release addresses #4

FFMpeg consumer with audio channel mapping

FFMpeg consumer (<stream> in casparcg.config) now can select audio channels to output. It is most useful for channels with passthru channel layout.
The channel list can also be provided when using CAPTURE command with CHANNEL_MAP parameter containing quoted list of channels to be recorded.

Fixes

Fixed:

• FFMpeg consumer int NTSC mode
• NDI producer compatibility for NDI Runtime 3.7.1

Output stream filtering

In this release output image processing may be done in one of two paths:

• when there is only need to change pixel format, it's done with fast, multi-threaded way using swscale library,
• when other processing is required, it may be done providing <filter> value in casparcg.config. This may be significantly slower, however it may also be multi-threaded, if FFMpeg itself allow it.

Also moved pix_fmt to <options>.

Added NDI producer from config file

For a channel, it's possible to open NDI source (as well as Decklink input) from casparcg.config file.
Example syntax is (under <channel>):

<input>
  <layer>0</layer>
  <ndi>
      <name>name_of_ndi_source</name> 
      <address>address</address> 
      <buffer-depth>3</buffer-depth>
  </ndi>
</input>

It's enough to provide name or address (host:port) of the source.