Wavenc and splitmuxsink won't work in async mode?

Application Development
1

Hi,

I’m working on a project to split streaming in a Go server utilizing splitmuxsink. Due to the go-gst version issue, the current pipeline can only work in async-finalize mode. It works well with MP4 and WebM streaming.
Now the requirement is to support splitting raw audio into WAV files. And I found it’s not as easy as setting muxer-factory with wavenc.

Some situation:

  • The CLI, “gst-launch-1.0 osxaudiosrc! splitmuxsink location=out_%d.wav muxer=wavenc max-size-time=10000000000”, works well. But by checking GST logs, I suppose it works in sync mode, e.g. async-finalize = FALSE. Is that true?
  • In async-finalize mode, the first fragment can be generated normally, but it seems GST fails to create new muxer/sink for the following fragments. Can’t understand why…

Some key code snippets from a standalone test on Mac (same operations without error handling):

gst.Init(nil)
pipeline, _ := gst.NewPipeline("pipeline")
src, _ := gst.NewElement("osxaudiosrc")
sink, _ := gst.NewElement("splitmuxsink")

sink.SetProperty("max-size-time", uint64(2000000000))
sink.SetProperty("async-finalize", true)
sink.SetProperty("muxer-factory", "wavenc")
sink.SetProperty("sink-factory", "appsink")

sink.Connect("sink-added", func(self *gst.Element, sink *gst.Element) {
	appSink := app.SinkFromElement(sink)
	appSink.SetCallbacks(&appSinkCallbacks)
})

pipeline.AddMany(src, sink)
src.GetStaticPad("src").Link((sink.GetRequestPad("audio_%u")))

pipeline.Start()

Above codes can generate the first wav file. When the second fragment is created, got below error from GST:

(<unknown>:78065): GStreamer-CRITICAL **: 15:51:07.464: gst_element_request_pad: assertion 'templ->presence == GST_PAD_REQUEST' failed

(<unknown>:78065): GStreamer-CRITICAL **: 15:51:07.467: gst_pad_link_full: assertion 'GST_IS_PAD (sinkpad)' failed

(<unknown>:78065): GStreamer-CRITICAL **: 15:51:07.467: gst_element_release_request_pad: assertion 'GST_IS_PAD (pad)' failed

(<unknown>:78065): GStreamer-CRITICAL **: 15:51:07.467: gst_object_unref: assertion 'object != NULL' failed

(<unknown>:78065): GStreamer-CRITICAL **: 15:51:07.467: gst_pad_send_event: assertion 'GST_IS_PAD (pad)' failed

(<unknown>:78065): GStreamer-CRITICAL **: 15:51:07.467: gst_object_unref: assertion 'object != NULL' failed

I noticed that the difference between mp4mux/webmmux and wavenc is mp4mux/webmmux has the pad templates " audio_%u" and wavenc has sink instead. Does this matter?

So my questions are:

  • Is it possible that splitmuxsink works with wavenc in async mode?
  • if it’s possible, then what’s missing/wrong in my practice?

Tested with GST 1.22.5 and 1.24.2.

Thanks in advance! And let me know if any other info is needed.

2

The code you provided looks okay (although I cannot help you with splitmuxsink)

I was wondering what you mean by “Due to the go-gst version issue, the current pipeline can only work in async-finalize mode”?

3

When I filed this issue, the go-gst hasn’t included the fix to issue#65, so I could only make splitmuxsink work in async mode at that time, and failed to split wav stream.

Later I found a workaround to set element instance through go-gst even without the fix, so I can enable sync mode of splitmuxsink. With sync mode wavenc works well with splitmuxsink.

So it looks like that wavenc can only work with splitmuxsink in sync mode. Is it WAI or a bug?

Thanks!