Hardsubs and Softsubs(Devil Doll, 2003-11-14)
There are two things that are summed up as being "fansubs" but are totally different in nature: "hardsubs" and "softsubs", as I try to coin a naming for them.
Hardsubs are video containers where the subtitles have been encoded into the video stream. You get all you need in one package, but you cannot separate the video from the subtitles then - it is like a program binary.
Softsubs are simple files (mostly text only) whose format depends on the exact subtitle encoding software to be used to interpret these. These are of no use unless you possess a video stream where you can insert them into. This insertion can now be done on a normal PC without hardcoding, by installing some separate DirectShow filter codec and having it insert these subtitles into the display of the video program "on the fly". You may then even do some editing of the subtitles, save the text file (which is then re-read by the subtitles codec automatically), rewind the video some seconds and instantly replay the scene with the modified subtitles!
Dynamically embedding softsubs into a video stream allows for easy production of modified subtitle versions, especially of those in any number of languages. You need some "raw" version of the video (be that taken from the purchased DVD or from some download source) and the DirectShow codec, and tell the codec which subtitle file to read - and that's it!
Especially all the timing and encoding work has to be invested just once (normally for the English version) and the translators to other languages have then little to do except for translating the English text lines into their target language. (Of course the quality of such a re-translation depends a lot on the quality of the English sub in the first place...) In this aspect softsubs are like the Open Source aspect of software in the WWW: The subbers give you their "source code" and you may adapt it to your own requirements, like a different language, adding colors for the "roles" of the characters, changing fonts, positions or sizes of the text lines, change the exact time of text display and whatever you would like to change.
As for the legal aspect, there might not be any difference between hardsubs and softsubs. But at least one might argue that a softsub text file would be of significant use for purchasers of an English (or even Japanese) DVD who aren't understanding English well enough - there are other countries besides the U.S., if you might have forgotten about that. ;-) So for Anime fans of 'restricted access' to understanding English it will be reasonable to search the 'appropriate ressources' for softsub files of their native language.
I finally got impatient and decided to go find the answer to my own question. Terms like "Hardsubbing" or "Hardsubs" were turning up occasionally in anime reviews I would read from various websites, and I was wondering what they meant. At a website called "Lazy Man's Guide to MKV" (whatever that is) I found the following definition:
"The average anime digisub uses SSA subs as well, but they are "hardsubbed". This means the subtitles are part of the image, and these subs are permanent. Hardsubs cannot switch languages or disable subtitles. Also, hardsubs use more bits than softsubs because the subtitles must be encoded with the image. The saved bits used in a softsub allow the video image to be clearer and crisper"
Devil Doll 2004-11-18:
Standard AVI video containers (Microsoft Audio/Video) can only hold hardsubs because they can only hold one video stream and a number of audio streams. That's why AVI files must contain hardsubs where the subtitles are hard-coded into the video stream.
But there are more modern and better container formats, such as Ogg Media (OGM) and Matroska (MKV) that can hold more and different types of streams, now even including text streams (normally SRT subtitle format but can be Substation Alpha (SSA) as well). In this case you can put a video stream and a subtitle text file into the container and decide whether to use the subtitles when watching the video. You can even have several subtitle files within one container and decide at playing time which of these to use (it may even be more than one at a time, so that one might put footnotes/technical comments into a separate subtitle stream etc.).
Which means that if you have a softsubbed video in one of these modern containers then you can even extract the subtitles and modify them (such as translating them into your own language, without needing to redo all the work of timing).
The downside of these modern containers is that they aren't (yet) supported by stand-alone DVD players (for TV sets without PCs) while the typical AVI files (even including modern video codecs such as DivX5 or Xvid) are fully supported by modern players nowadays.