qtdemux: Add support for AC4

Submitted by Savinderjit Kaur

Link to original bug (#789810)

Description

Created attachment 362804
Patch for generating proper caps for AC4 content

The caps received from qtdemux for AC-4 content are audio/x-gst-fourcc-ac_4.
The attached patch has been created for generating proper caps (audio/x-ac4). Please let me know if this is valid for submission.

Patch 362804, "Patch for generating proper caps for AC4 content":
qtdemux_ac4_caps.patch

Version: 1.x