Switch blank video from smpte to a missing-codecs message

[nirbheek]

/r/linux_gaming and other forums regularly get posts asking about "weird colors" in games with cutscenes:

https://www.reddit.com/r/linux_gaming/comments/1kf59i6/fragpunk_showing_weird_colors/

https://www.reddit.com/r/linux_gaming/comments/1k47643/blue_prince_game_launches_but_when_i_click_new/

https://www.reddit.com/r/linux_gaming/comments/1ftevcl/star_wars_jedi_survivor_is_giving_me_a_weird/

Putting a message in there is probably more useful.

Also switch audio to use wave=silence, which is more correct.

This is what the video will look like after this change:
. As a bonus, the video will also be smaller.

[nirbheek]

Note that this change requires the textoverlay element which is part of the pango plugin. Since this MKV is generated at build-time this doesn't change the runtime requirements of Proton, but it does require that the gstreamer that you use on your build machines ship that pango gstreamer plugin. I noticed that this build-env gstreamer is already different from the gstreamer you ship with Proton since it ships with an av1 encoder, and Proton does not.

Note that the pango plugin is shipped by default on all Linux distros, so it should be easy to gain access to.

[nirbheek]

Could you overlay it on the test pattern? That may be the best of both worlds.

Done. I also made the pattern move and made it loop perfectly. I figured that you might've wanted movement to clarify that the game is not frozen. The change was:

- num-buffers=120 pattern=black
+ num-buffers=160 horizontal-speed=2