[MPlayer-dev-eng] [DOCS] [3rd try] missing option descriptions

Diego Biurrun diego at biurrun.de
Sat Aug 30 11:32:09 CEST 2003

D Richard Felker III writes:
 > On Mon, Aug 25, 2003 at 02:00:37AM +0200, Arpi wrote:
 > > > - (no)autoexpand
 > > > 
 > > >   Rich made some mysterious rumbling about this being a very obscure
 > > >   option that was added for some encoding work he needed to do and he
 > > >   was unsure whether such a hack should be documented at all..  I'd
 > > >   say document or remove, so I guess we should go for the former.
 > > 
 > > ok this is not easy.
 > > as you probably know, OSD rendering in g1 is handled by vo drivers.
 > > (it has historical reasons, osd existed before filter layer).
 > > but mencoder doesnt use libvo, but users still want osd rendering with it,
 > > to render subtitles into the encoded avi (which is silly anyway).
 > > to workaround this, mencoder by default inserts the 'expand' video filter,
 > > which can do the osd rendering. but since we support slices, and DR and some
 > > other tricks has been done in vf_expand, sometimes it's broken/buggy/slow,
 > > so it's better not inserting it at all. so, to avoid auto-inserting expand
 > > filter in mencoder, you can use -noautoexpand
 > Yes, Arpi is mostly right about this, but it has another use. IMO,
 > subtitles look MUCH better when rendered at high resolution then
 > scaled by swscaler, as opposed to rendered at low res. So when I was
 > making small encodes with hardcoded subs for hopeless WMP users who
 > can't figure out how to install the .srt filter or whatever :))))) I
 > wanted to render subs at the beginning of the filter chain rather than
 > the end. However, mencoder's auto-inserted vf_expand always renders
 > subs, so it was double-rendering them, and doing it in a bogus manner
 > since the OSD code does not support multiple instances (image/font
 > size are initialized only once)... The only clean way I found around
 > this problem was to allow the user to disable the auto-inserted expand
 > filter.

Hmm, this is tricky indeed.  What about:

  Do not automatically insert the expand filter into the MEncoder filter chain.
  Useful to control at which point of the filter chain subtitles are rendered
  when hardcoding subtitles onto a movie.


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