Adds an object for storing FFmpeg variables. This allows any argument type to be added at any time, removing the limitation of having to add to the command in a specific order.
Makes stream objects store the index of the input file they belong to.
Saves the result of probes to a record that's easy to pass around.
Always passes all probed files to the input files of ffmpeg.
Makes it easier to enable h26x encoding/decoding when necessary.
Removes the hard-coded behavior for external subtitles, and allows any stream to be an external stream.