[Bug 58425] video/x-h264 alignment=au caps causes artifacts and crashes with "almost-aligned" streams

[WineHQ Bugzilla]

http://bugs.winehq.org/show_bug.cgi?id=58425

--- Comment #8 from Brendan McGrath  ---
I ran the following (on Ubuntu using default repos):
$ apt-cache depends libwine | grep gstreamer

and got:
  Depends: libgstreamer-plugins-base1.0-0
  Depends: libgstreamer1.0-0
  Recommends: gstreamer1.0-plugins-good
  Suggests: gstreamer1.0-libav
  Suggests: gstreamer1.0-plugins-bad
  Suggests: gstreamer1.0-plugins-ugly

So I guess h264 decoding wouldn't work with a default install anyway (i.e.
without --install-suggests). avdec_h264 requires gstreamer1.0-libav, and the
other h264 decoders I looked at needed gstreamer1.0-plugins-bad.

What about other downstream projects? Do they all include
gstreamer1.0-plugins-bad?

Alternatively, I was thinking I could separate the caps into:
- known values; and
- assumed values

Then apply the assumed values only when we don't have a parser.

For example, using H.264, assumed values are:
gst_caps_set_simple(caps, "stream-format", G_TYPE_STRING, "byte-stream", NULL);
gst_caps_set_simple(caps, "alignment", G_TYPE_STRING, "au", NULL);

But if a parser is present, we don't have to assume those values (as the parser
will determine them for us).