How does Rust work with process arguments? - command-line

Question

I'm really confused about Rust processes. I'm trying to call something like this:
ffmpeg -i path/to/test-video.webm -ab 160k -ac 2 -vn -f mp3 -
This should extract sound out of video and send it to stdout. So I've done this:
let sound: std::process::Output = Command::new("ffmpeg")
.arg(format!("-i {}", args.input.to_str().unwrap()))
.arg("-ab 160k")
.arg("-ac 2")
.arg("-vn")
.arg("-f mp3")
.arg("-")
.stdout(Stdio::piped())
.stdin(Stdio::inherit())
.stderr(Stdio::inherit())
.output()
.unwrap();
But for some reason, this doesn't work. It prints this to stderr:
Unrecognized option 'i path/to/test-video.webm'.
Error splitting the argument list: Option not found
When I remove the slashes from args (so it looks like .arg(format!("i {}", ...)).arg("ab 160k")..., I get this:
Output file #0 does not contain any stream
I think I misunderstood how this works, but I tested it on other applications and it seemed to work the way I'm doing it now. What did I miss, how does Rust work with these arguments?
And just to be clear, I know about the ffmpeg crates, but they don't work for me for some reason, I can't even compile them.

Answer 1

try this
let sound: std::process::Output = Command::new("ffmpeg")
.arg("-i")
.arg(args.input.to_str().unwrap())
.arg("-ab")
.arg("160k")
.arg("-ac")
.arg("2")
.arg("-vn")
.arg("-f")
.arg("mp3")
.arg("-")
.stdout(Stdio::piped())
.stdin(Stdio::inherit())
.stderr(Stdio::inherit())
.output()
.unwrap();