Function generate_sfx 

pub fn generate_sfx(
    entries: &[PlanEntry],
    cfg: &SfxConfig,
    stems_dir: &Path,
    sfx_dir: &Path,
    start_from: i64,
    backend: &mut dyn SfxBackend,
) -> Result<()>

generate_sfx(entries, config, stems_dir, sfx_dir=, start_from=, backend=).