Function build_live_video_args 

pub fn build_live_video_args(
    config: &EncoderConfig,
    intermediate: &Path,
) -> Result<Vec<String>, EncodeError>

Build the gst-launch-1.0 argv for the live video-only encode (M-QUAL.1). Frames arrive on the child’s stdin (fd=0) as raw BGRA; the pipeline encodes them straight to a compressed video-only container at intermediate. The audio leg is handled separately at finalize (build_remux_args).

Shape: -q -e fdsrc fd=0 ! rawvideoparse format=bgra width=W height=H framerate=F/1 ! videoconvert ! <encoder> ! <parser> ! <mux> ! filesink location=<intermediate>.

Errors

EncodeError::Unsupported if the (format, OS) combo has no wired encoder.