GStreamer crashes when volume is set to 0 for raw PCM audio data with sink timestamp sync turned off

Submitted by Andrei Mikheev

Link to original bug (#793081)

Description

Our raw PCM data does not have timestamps for the pipeline and it causes volume plugin to crash with messages complaining about a timestamp expected when we set the volume to 0 or mute. Note that we use autoaudiosink with "sync=false" option.

How to reproduce:

gst-launch-1.0 -v filesrc location=rawpcm.wav ! decodebin ! queue ! audioconvert ! volume volume=0 ! autoaudiosink sync=false

The version of this with volume set to non-zero value actually works:
gst-launch-1.0 -v filesrc location=rawpcm.wav ! decodebin ! queue ! audioconvert ! volume volume=1 ! autoaudiosink sync=false

Version: 1.x