I get error when try SetPropery "muxer" for the "splitmuxsink" plugin.

[artofey]

Gstreamer's documentation allowed set property "muxer' for elelment "splitmuxsink".
But I got error in this code example:

pipeline, _ := gst.NewPipeline("")
splitMux, _ := gst.NewElement("splitmuxsink")
mux, _ := gst.NewElement("mp4mux")
splitMux.Set("muxer", mux)

err: fatal error: checkptr: pointer arithmetic result points to invalid allocation

I have tried other uses as well:
splitMux.Set("muxer", mux.GObject())
splitMux.Set("muxer", *mux)
but I also get errors (but different ones)

Does this library allow me to do what I want? When using the C language, I can do this easily.

[Medina312]

Hi, I don’t know

[artofey]

I think the proplem is here

For different runs of the same code, C.g_object_class_find_property function returns with random paramSpec.value_type values...

Function GetPropertyType return not valide Type.
GetPropertyType function returns wrong type. So this condition is true and we get an error

[clintlombard]

I'm having a similar issue with setting the active-pad property (requires *GstPad) of an input-selector element.

package main

import (
	"fmt"
	"log"
	"time"

	"github.com/tinyzimmer/go-gst/gst"
)


func main(){
	gst.Init(nil)
	pipeline, _ := gst.NewPipeline("")
	src0, _ := gst.NewElement("videotestsrc")
	src1, _ := gst.NewElement("videotestsrc")
	inputSelector, _ := gst.NewElement("input-selector")
	fakesink, _ := gst.NewElement("fakesink")

	pipeline.AddMany(
		src0,
		src1,
		inputSelector,
		fakesink,
	)
	src0.LinkFiltered(inputSelector, gst.NewCapsFromString("video/x-raw, framerate=16/1"))
	src1.LinkFiltered(inputSelector, gst.NewCapsFromString("video/x-raw, framerate=16/1"))
	inputSelector.Link(fakesink)
	pipeline.SetState(gst.StatePlaying)

	if inputSelector.GetState() != gst.StatePlaying {
		time.Sleep(10*time.Millisecond)
	}

	// Check the current active pad
	prop, _ := inputSelector.GetProperty("active-pad")
	fmt.Println("active-pad:", prop.(*gst.Pad).GetName())

	// Change the active pad
	pad := inputSelector.GetStaticPad("sink_1")

	err := inputSelector.SetProperty("active-pad", pad)
	if err != nil {
		log.Fatalf("Input selector failed to change inputs: %v\n", err)
	}
}

Output:

active-pad: sink_0
panic: runtime error: cgo argument has Go pointer to Go pointer

goroutine 1 [running]:
github.com/tinyzimmer/go-glib/glib.(*Value).SetPointer.func1(0xc000010060, 0x16)
        go/pkg/mod/github.com/tinyzimmer/[email protected]/glib/gvalue.go:557 +0x32
github.com/tinyzimmer/go-glib/glib.(*Value).SetPointer(0x55c720, 0xc000010058)
        go/pkg/mod/github.com/tinyzimmer/[email protected]/glib/gvalue.go:557 +0x19
github.com/tinyzimmer/go-glib/glib.gValue({0x55c720, 0xc000010058})
        go/pkg/mod/github.com/tinyzimmer/[email protected]/glib/gvalue.go:284 +0xa08
github.com/tinyzimmer/go-glib/glib.(*Object).SetProperty(0x587440, {0x55fed7, 0xa}, {0x55c720, 0xc000010058})
        go/pkg/mod/github.com/tinyzimmer/[email protected]/glib/gobject.go:211 +0x4f
main.main()

Seems like the issues is in go-glib. I've narrowed it down to gValue that can't handle *GObject derivatives like *GstObject so instead you must use .GObject(), i.e.

err := inputSelector.SetProperty("active-pad", pad.GObject())

This, however, opens another can of worms, because in SetPropertyValue it checks if the property type matches the value type, and this fails. The output now being

active-pad: sink_0
2022/03/17 13:57:29 Input selector failed to change inputs: Invalid type GObject for property active-pad

To fix this I think a simple solution would be to adjust the check in SetPropertyValue from

	if valType != propType {

to

	if !(valType.IsA(propType) || propType.IsA(valType)) {

@tinyzimmer how do you feel about this?

[normen]

+1

[RSWilli]

@artofey move this issue to https://github.com/go-gst/go-gst (where future development of the bindings will take place) if you think it is necessary.

Alternatively move the linked PR to https://github.com/go-gst/go-glib