Work around negotiation problem in jackaudiosrc that causes it to negotiate...

                src

            }

            ["jack", client_name] => {

                let bin = gst::Bin::new(None);

                let src = gst::ElementFactory::make("jackaudiosrc", None)

                    .context("Creating jackaudiosrc")?;

                src.set_property("client-name", client_name)

                    .expect("Failed to set client-name property on jackaudiosrc");

                src.set_property_from_str("connect", "none");

                src

                let capsfilter =

                    gst::ElementFactory::make("capsfilter", None).context("Creating capsfilter")?;

                // Workaround for jackaudiosrc negotiating stereo if downstream

                // has converters before the other capsfilter

                let caps = gst::Caps::builder("audio/x-raw")

                    .field(

                        "channels",

                        &(match cfg.channel_configuration {

                            crate::config::ChannelConfiguration::Mono => 1i32,

                            crate::config::ChannelConfiguration::Stereo => 2i32,

                        }),

                    )

                    .build();

                capsfilter

                    .set_property("caps", &caps)

                    .expect("Failed to set caps property on capsfilter");

                bin.add_many(&[&src, &capsfilter])

                    .expect("Failed to add elements to jackaudiosrc bin");

                src.link(&capsfilter)

                    .expect("Failed to link jackaudiosrc to capsfilter");

                bin.add_pad(

                    &gst::GhostPad::with_target(

                        Some("src"),

                        &capsfilter

                            .get_static_pad("src")

                            .expect("No src pad in capsfilter"),

                    )

                    .expect("Failed to create ghost pad"),

                )

                .expect("Failed to add ghost pad to jackaudiosrc bin");

                bin.upcast()

            }

            ["audiotest", frequency] => {

                let src = gst::ElementFactory::make("audiotestsrc", None)