The tmsg stuff was for the internal gettext() based translation system,
which nobody ever attempted to use and thus was removed. mp_gtext() and
set_osd_tmsg() were also for this.
mp_dbg was once enabled in debug mode only, but since we have log level
for enabling debug messages, it seems utterly useless.
In general, this warning can hint to actual bugs. We don't enable it
yet, because it would conflict with some unmerged code, and we should
check with clang too (this commit was done by testing with gcc).
Both converters can output \pos and deal with font sizes, so they assume
a specific script resolution (PlayResX/PlayResY). The implicit
assumption was that a specific resolution was guaranteed. The
MP_ASS_FONT_PLAYRESY constant is connected to this.
Better make it explicit, so that the implicit dependency on
MP_ASS_FONT_PLAYRESY is removed. (Unfortunately, libavcodec sub
converters still don't set PlayResX/PlayResY explicitly, so the value
set by that constant can't be declared as arbitrary yet.)
PlayResY=288 is most likely the SSA natural script resolution (or
something like this?), as well as the libass and VSFilter default.
PlayResX=384 is the fallback value set by libass if PlayResY is set to
288, and PlayResX is unset.
This means subassconvert.c is split in sd_srt.c and sd_microdvd.c. Now
this code is involved in the sub conversion chain like sd_movtext is.
The invocation of the converter in sd_ass.c is removed.
This requires some other changes to make the new sub converter code work
with loading external subtitles. Until now, subtitles loaded via
subreader.c was assumed to be in plaintext, or for some formats, in ASS
(except in -no-ass mode). Then these were added to an ASS_Track. Change
this so that subtitles are always in their original format (as far as
decoders/converters for them are available), and turn every sub event
read by subreader.c as packet to the dec_sub.c subtitle chain.
This removes differences between external/demuxed and -ass/-no-ass code
paths further.
