Error requesting audio pad from dashsink element

Application Development
1

Hi, I’m having an issue requesting an audio pad from the dashsink element in Rust, it appears that the pad name is lost when reaching the C code.

Here’s a code snippet to replicate this

let pipeline = gst::Pipeline::new();
let dash_sink = gst::ElementFactory::make("dashsink").build()?;

pipeline.add(&dash_sink).unwrap();

let video_pad = dash_sink.request_pad_simple("video_%u").unwrap(); // This works fine
let audio_pad = dash_sink.request_pad_simple("audio_%u").unwrap(); // This panics

GST_DEBUG output:

GStreamer-CRITICAL **: 10:17:46.504: gst_element_request_pad_simple: assertion 'name != NULL' failed
0:00:00.008628996 400642 0xffff54003f00 ERROR               dashsink gstdashsink.c:993:gst_dash_sink_request_new_pad:<dashsink0> Unable to request pad name (null)

GDB Output (Rust side)

#9  0x0000aaab653267b4 [PAC] in gstreamer::element::ElementExtManual::request_pad_simple<gstreamer::auto::element::Element> (self=0xffff556d6868, name=...)
    at /home/guillaume/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/gstreamer-0.23.5/src/element.rs:648
648	                from_glib_full(ffi::gst_element_request_pad_simple(
(gdb) print name
$1 = "audio_%u"

GDB Output (C side)

#8  0x0000ffff56f5d9b4 [PAC] in _gst_element_request_pad (element=0xffff44323990 [GstDashSink|dashsink0], templ=0xffff44162f20 [GstPadTemplate|audio_%u], name=0x0, caps=0x0)
    at ../gstreamer-1.24.11/gst/gstelement.c:1179
1179	    newpad = (oclass->request_new_pad) (element, templ, name, caps);
(gdb) print name
$2 = (const gchar *) 0x0

Does anyone have any idea why this is happening, or if there’s something obviously wrong I’m doing ?

2

As we discussed two weeks ago on Matrix, this is a bug in dashsink and to work around it you would have to pass audio_0 and similar instead of audio_%u for now.

You wanted to create an MR but it seems like you forgot, so I created one now: dashsink: Make sure to use a non-NULL pad name when requesting a pad from splitmuxsink (!8697) · Merge requests · GStreamer / gstreamer · GitLab

1 Like
3

Sorry about that, I had a patch ready but with the whole Gitlab being down thing I ended up forgetting.

Thanks for your help

1 Like