This would be absolutely lovely, I recall back in the early days of unix commandline codecs, we had the ultra-flexible option to piping data around through own custom scripts/executables, everything talked to everything by platform design, then Windows came along and began creating brickwalls.
Let's say the ability to pipe out via stdout to a custom application of our choosing. So say in the encoders list we just select 'custom' and then type in a freetext commandline, independent for video and audio, this way advanced users can use their own custom workflow with the plugin.
Kind of stems off the back of the other feature request which got rejected because it was outside the scope of Voukoder's purpose.
I guess from a development perspective all it would require is instantiating a stdout to a shell running the commandline entered by user.
This will make Voukoder very flexible going forward, I have a fair few dozen python scripts which already work off stdout from ffmpeg itself, so I could chain in this way for a very specific workflow straight out of the premiere export door all thanks to Voukoder giving techs backdoor access to the streams.
Though I can imagine some in the future might request a raw multiplexed outgoing stream, so say FFMPEG just packages and shunts it out the door to stdout where whatever custom program or even say a script running its own ffmpeg process then does wierd and wonderful things for bespoke workflow requirements.