From Buzztard

This should be a bin derived element. When creating a btsong it needs a btapplication to get the bin from. Thus bt-bin would need to have a minimal bt-bin-app. It will create a btsong and pass the bt-bin-app to set itself as the 'bin'.

[edit] Dummy sink

It also needs to provide a dummy btsinkmachine that it will set as a master. As btsinkmachine always uses btsinkbin, the later needs a pass-through mode (we already have the record modes). I don't see a way to avoid sink-bin right now.

The bin needs to set the src-pad of the sink-bin's last element (input-gain) as a ghost-pad for itself (we could make it a sometimes pad maybe if we want to add a pad-template). Also the actual BtSinkMachine woul need to have such a ghostpad.

[edit] Typefinders

We somehow need to wrap the songio-detect mechanism into a typefinder. This is needed so that playbin would actually autoplug this element.