gst-validate: considers as a failure if decoder changes width, height or framerate.

Submitted by Hyunjun Ko @zzoon

Link to original bug (#785211)

Description

Created attachment 356087
mpeg2 sample

Reproduce step:
gst-validate-1.0 filesrc location=sony-ct1.mpeg ! mpegvideoparse ! avdec_mpeg2video ! fakesink

It results in:
=== Got criticals. Return value set to 18 ====
Critical error Field width from setcaps caps 'video/x-raw, format=(string)I420, width=(int)352, height=(int)224, interlace-mode=(string)mixed, multiview-mode=(string)mono, multiview-flags=(GstVideoMultiviewFlagsSet)0:ffffffff:/right-view-first/left-flipped/left-flopped/right-flipped/right-flopped/half-aspect/mixed-mono, pixel-aspect-ratio=(fraction)4/3, chroma-site=(string)mpeg2, colorimetry=(string)bt601, framerate=(fraction)30/1' is different from expected value in caps 'pending-fields, width=(int)120, height=(int)120, framerate=(fraction)30/1, pixel-aspect-ratio=(fraction)4/3;'

Because decoder changes resolution of src caps with real encoded size and set them to output_state and seems gst-validate considers this as a failure.

I got same result with other vp9 files using vp9dec.

I'm wondering if this is real failure.

Attachment 356087, "mpeg2 sample":
sony-ct1.mpeg