Print flow return as string in log message; if we check the return
value of gst_buffer_new_and_alloc() we should use the _try() function
that might actually return NULL. Post error message when returning
GST_FLOW_ERROR. Use portable GLib macros to print 64-bit integers.
Don't use 0LL, that's also not portable (and unneeded here).
Only put primary language into GST_TAG_LANGUAGE, and convert to lower case,
ie. only use "en" of "en_GB". This is per our tag documentation and hence
what apps expect. Also add example to kateenc property description so people
know a language code is wanted here.
katedec: Kate decoder (text only)
kateenc: Kate encoder (text and DVD SPU only)
katetag: Kate tagger
kateparse: Kate parser
tiger: Kate renderer using the Tiger rendering library
Fixes#525743.
