[MPlayer-dev-eng] Font hinting in libass

Uoti Urpala uoti.urpala at pp1.inet.fi
Thu Apr 19 01:30:27 CEST 2007

On Thu, 2007-04-19 at 02:40 +0400, Vladimir Mosgalin wrote:
> Hi Uoti Urpala!
>  On 2007.04.19 at 00:09:27 +0300, Uoti Urpala wrote next:
> > I think there should be a way to disable native hinting, but I'm not
> > sure whether it should be an option (including all the flags above?) or
> > if some other mode would be suitable as a default.
> Well, at least it should be tested separately on freetype compiled with
> native hinting and without one.

Why? Wouldn't that just mean some of the hinting options fall back to

>  I suspect that most people don't care
> about fonts and use freetype without bytecode interpreter, since
> regular hinting together with urw-fonts or dejavu-fonts, "out of the
> box" setup for most distributions produces more or less satisfying
> results. Still, people who have recompiled freetype with BCI enabled
> probably care more about fonts quality and will likely to see problem
> with subtitle fonts.

At least current Debian ships FreeType with the bytecode interpreter
fully enabled by default.

> Anyway, if I understand your problem right, you mean that "native
> hinting" method (BCI) produces bad results on embedded fonts, while
> producing nice results on the same fonts when they aren't embedded and
> different load method is used?

No, I meant those fonts produce bad results when "native" hinting is
enabled. I do not have a reason to believe things would be any different
if I'd extract them and then use a different load method.

> If you found some embedded font which always renders worse with BCI
> enabled (no matter if embedded or not), it sounds like freetype bug
> too.. freetype simply has problems with rendering some fonts.
> Can you provide link to subtitles or video with embedded font? I'd like
> to see that kind of bug.

Try the font I posted earlier. The most easily verifiable problem I
noticed is that with "native" hinting 'i' and 'j' are too tall compared
to other small letters. If you try rendering a string like "ririri" it
should be pretty clear.

Why do you think it has to be a FreeType bug? Surely there are at least
a few fonts floating around that really have incorrect hinting
information and render badly if it's used?

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