Why sometime parse_launch pipeline will report StateChangeError if set_state afterward (in gstreamer-rs)

Application Development
1

Hello all:) I’m using gstreamer-rs rust bindings and trying to run the pipeline which I can run successfully with gst-launh-1.0, and it always fails with error.

I cant be sure whether there is something I dont know about the usage for gstreamer parse_launch or there could be issue in gstreamer-rs?

rust code:

#[cfg(test)]
mod tests {
    use gst::prelude::*;

    #[test]
    fn gstreamer_push() {
        gst::init().unwrap();

        let pipeline = gst::parse_launch("flvmux name=mux ! rtmpsink location='rtmp://localhost/live/test' filesrc location='D:/Download/test.mkv' ! decodebin3 name=d d. ! queue ! videoconvert ! x264enc tune=zerolatency ! mux. d. ! queue ! audioconvert ! voaacenc ! mux.").unwrap();

        // pipeline.set_state(gst::State::Paused).expect("Unable to prepare pipeline for paused");
        pipeline.set_state(gst::State::Playing).expect("Unable to prepare pipeline for playing");

        let bus = pipeline.bus().unwrap();

        for msg in bus.iter_timed(gst::ClockTime::NONE) {
            use gst::MessageView;

            match msg.view() {
                MessageView::Eos(..) => break,
                MessageView::StateChanged(s) => {
                    dbg!(s.old(), s.current());
                },
                MessageView::Error(err) => {
                    dbg!(err.src().map(|s| s.path_string()), err.error(), err.debug());
                },
                _ => (),
            }
        }

        // Terminating player and close all pipepline sources by setting state to null.
        pipeline.set_state(gst::State::Null).unwrap();
    }
}

It alway fail with StateChangeError.

When I run a simple pipeline like let pipeline = gst::parse_launch(&format!("playbin uri={uri}")).unwrap();, it works fine though.

Expected Behavior

According to the gstreamer documentation, parse_launch should support gst-launch-1.0 commands and run successfully.

Observed Behavior

Unable to prepare pipeline for playing: StateChangeError
thread 'tests::gstreamer_push' panicked at stream\src\main.rs:27:49:
Unable to prepare pipeline for playing: StateChangeError
stack backtrace:
   0: std::panicking::begin_panic_handler
             at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/library\std\src\panicking.rs:595
   1: core::panicking::panic_fmt
             at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/library\core\src\panicking.rs:67
   2: core::result::unwrap_failed
             at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/library\core\src\result.rs:1652
   3: enum2$<core::result::Result<gstreamer::enums::StateChangeSuccess,gstreamer::enums::StateChangeError> >::expect<gstreamer::enums::StateChangeSuccess,gstreamer::enums::StateChangeError>
             at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33\library\core\src\result.rs:1034
   4: stream::tests::gstreamer_push
             at .\src\main.rs:27
   5: stream::tests::gstreamer_push::closure$0
             at .\src\main.rs:21

Setup

  • Operating System: Windows 11
  • Device: Computer
  • gstreamer-rs Version: 0.21.1
  • GStreamer Version: 1.22.5
  • Command line: gst-launch-1.0 flvmux name=mux ! rtmpsink location='rtmp://localhost/live/test' filesrc location='D:/Download/test.mkv' ! decodebin3 name=d d. ! queue ! videoconvert ! x264enc tune=zerolatency ! mux. d. ! queue ! audioconvert ! voaacenc ! mux.
2

Have you tried without the single apostrophes - those are for the shell usually, I don’t know if parse_launch() will parse them.

Perhaps don’t check for the result of the state change, but instead look for error messages on the bus, which will also have more information.

1 Like
3

Can you get a debug log with GST_DEBUG=6 of both your code and the gst-launch-1.0 pipeline?

As both pipeline strings are the same they should theoretically also behave the same so there’s probably some difference in the environment that would be visible from the logs.

4

You are right, removing those single apostrophes makes the code compiles and runs succesfully. This is really tricky for me. Thanks a lot for your hint and suggestion!

5

Thanks for your attention. After being reminded of the single apostrophes used in parse_launch, I remove them and the code works good. A tricky problem.

1 Like
6

Double quotes is supported in parse_launch though. And using double quotes will support blanks in path.

7

True. I use " in my pipeline string.

location=\"rtmp://localhost/live/test\"