handle_segment_change
Description:
When enabled, appsrc will check GstSegment in GstSample which was pushed via push_sample or "push-sample" signal action.
If a GstSegment is changed, corresponding segment event will be followed by next data flow.
FIXME: currently only GST_FORMAT_TIME format is supported and therefore GstAppSrc: format should be time. However, possibly Src can support other formats.