[MEncoder-users] Generating switchable binary subtitles with MEncoder

[Francois Visagie]

On 10/29/07, Giacomo Comes <comes at naic.edu> wrote:
> On Mon, Oct 29, 2007 at 06:53:54PM +0200, Francois Visagie wrote:
> >
> > Also, the whole reason I hoped to turn to MEncoder for encoding binary
> > subtitles was because I got turned off spumux (I am actually using
> > dvdauthor for authoring). The reasons in my case were 1) unless you
> > provide it with SSA subtitles, it adjusts the timing with no way of
> > disabling that behaviour (and I'm recreating DV DATECODE display which
> > depends on perfectly adjacent subtitles to prevent flashing) and
>
> Can you clarify what you mean with "it adjusts the timing"?
> What spumux does that you want to disable?

DATECODE values have 1-second precision and are stored once a second.
The ripped DATECODE subtitles are 1s long each. When displayed as text
subtitles, this creates the appearance of a persistent, smoothly
updating date/time read-out. However spumux shortens the subtitles a
little to prevent adjacency, which is exactly what I didn't want since
that causes a flashing effect.
>
> > 2) it doesn't do anti-aliasing. In fact it only seems to use text and border
> > colours, possibly in addition to background which is transparent of
> > course.
>
> The code in spumux that render text subtitles in graphic subtitles
> comes from mplayer. So basically both should do the same work.
> About anti-aliasing, what I know is that it requires a lot of colors.
> ImageMagick when it renders a one color text with anti-aliasing can use
> up to 256 different colors. The rendering looks very nice, but then
> if you put it in a DVD subtitle you cannot have more that 4
> colors in total. How do you keep the anti-alias effect if you can only
> use 1 or may be 2 colors for the text and 1 or 2 for the border?
> I suspect that MPlayer use anti-alias and it looks nice because when
> it displays the subtitle on screen it can use as many colors as it needs.
>
> But I may be totally wrong on this as I'm not an anti-alias expert.
> If what I'm saying is incorrect I hope somebody else can correct me.

In my view you're on the right track here. When hard-coding subtitles
a program can proverbially take all the time and colours in the world.
Having said that, I know for a fact that spumux only uses two colours.
MaestroSBT uses colours better and produces better quality DVD
subtitles, but I still have to find a way to mux those into the
dvdauthor project with unaltered timing.

Kind regards,
Francois