id3demux : Does not send segment-start and segment-done message

Submitted by Baby octopus

Link to original bug (#795882)

Description

I have developed an application to stream a file indefinitely by looping it. For looping, I do a segment seek and then catch the SEGMENT_DONE message. However, this approach works for Mp4 and not work for mp3. Digging deeper, I found id3mux does not send these messages

One another issue here is the id3demux is optional for mp3 decoding. Decodebin does not autoplug id3demux for certain mp3 files but directly uses the mpegaudioparse. I'm not really sure which element is to send segment-start and segment-done messages in such a case