20.1.1 Multichannel fork

For testing purpose.
This release corrects the ffmpeg libraries for proper support of libopus with mpegts.
The disabling of frame drops has been replaced by the possibility to have a much larger drop threshold (1 min instead of 700 ms before frame start being dropped).
The win x64 binaries are the release ones not the RelWithDeb ones; hence the decreased size of the exe.