Over the past few weeks, I've come across a few groups (which shall remain nameless) that seem to be stuck in a vsfilter way of doing thing. To me, these groups are apparently slow to react or oblivious to the need for scripts that are friendly to libass (and perian).
Take episode one of 'Winter Series X' for example, the episode was typeset in such a way that it was capable of crashing or lagging even the most recent of MPlayer builds. The problem was three-fold.
- Apparently libass doesn't like \pos tags with decimals.
- Enormous letters that appear on screen and speed by with ridiculous placement values are a no-no.
- Using Japanese style brackets in scripts will bring fontconfig to its knees.
Fortunately, keen-eyed Linux users like myself are very quick to point out these problems and if the group is smart, they release patches or a v2. ;)
But the problem is deeper than the actual bugs themselves. Fansubbers cannot simply assume that their softsubs or even encodes will play properly on Linux. At the very least, you should run a script through MPlayer on a Linux virtual machine to see if everything renders properly.
To get a sense of how things 'work' on Linux, we need to be informed of the current state of affairs for the software critical to playing fansubs (not necessarily softsubs).
MPlayer and its frontends such as SMPlayer, have been stable for relatively proper decoding for years. There are really no outstanding issues here, however, some will argue that the correct-pts option is pretty essential for proper scene-timing to render precisely and accurately.
The standard for softsubs on Linux. At heart, libass is a clone of vsfilter and boasts the code to match. libass isn't perfect though, as I mentioned above, it can be quirky at times. Aside from that, libass is capable of handled pretty any karaoke or softsub effects that you throw at it.
A year ago, this player was absolute shit. Today, it is polished turd that can handle styled softsubs through libass. The fansub community is owed a ton of thanks from the VLC dev team for the progress that has been made so far. If not for the lobbying and bug hunting of the Aegisub devs and brave testers like myself, it would still be an unusable player. In some senses, it still is unusable because of the horrid AVC decoding.
Part of the Gnome desktop for Linux and standard on most Gnome-based distros, Totem is still a work in progress as far as I'm concerned. It has up to date decoding, but the softsub support is still very primitive and does not support styling. The heart of this problem is rooted in the gstreamer backend it relies on. I am currently pushing hard for styled subs to be included and progress based on libass seems promising, despite a noteworthy performance penalty.
Based on the xine backend. No data aside from the fact that certain Linux players make use of Xine and that styled softsubs are not supported.
~~~ Known libass quirks ~~~
- Transparency breaks if you use shadows
- Anti-aliasing breaks if you use transparency
- If you use decimal points on some tag it practically ignores the tag
- No \be (blur edges) strength
- No implementation for any of the tags in vsfilter 2.39c
- No @font support