Adding hardsubs to avi without recompressing

[sauzan]

I'm sorry if this sounds stupid but i cant seem to find the answer anywhere.

The situation is this : I have an avi file, with video and audio already compressed. I have a subtitle file in .ass format. What can I do to create the hardsub without recompressing the video again? Thought of using avimux but that dont support ass format..

[castellanos]

Use Subtitle Work Shop to convert your ass file into srt, then try to use AVIMux again.
Greetings! :)

[niamh]

It will be soft subs though, there is no way to insert hard subs without reencoding.

[chipzoller]

The best way to do this (albeit you will have to recode slightly) is probably to use VirtualDub and load your video file and choose fast recompress and use the textsub filter to add those subs into the AVI. I have not had great experience using AVIMux, pretty crappy utility in my experience.

[sauzan]

Thanks for the replies!

I am quite concerned with keeping the quality and size of the original avi file. Is there any difference between the fast recompress and full processing mode in this case?

Just wondering how the anime fansubbers did it, the quality of the subbed avi still seems pretty good

[chipzoller]

Sauzan,

I suppose the first thing I would try is the AVI mux utility within VobSub although I can't guarantee it's functionality as I have had minimal success using this tool.

I know what you are asking and I've have tried to do this many times unsuccessfully with AVI mux. I would try this first and then if that doesn't work you'll have to fast recompress. The quality shouldn't degrade too much and in the end you'll have your AVI with those text subs. I am not aware of another tool out there that will mux in subtitles with an already created AVI.


Chip

[Liisachan]

If you have to add subs losslessly (i.e. without losing the quality of the original vid), the only way is softsubbing.
If you have to hardsub, you'll lose the quality of the vid, more or less (but the loss can be small and can be acceptable).

You cannot use textsub.vdf in the Fast recompress; basically you have to use the Full recompress to use textsub.vdf (if not via AVS). In the Full recompress, the color space of the input is converted to RGB, and then again reconverted to YV12 etc. In theory, that can be very slightly lossy, but in this case, you can ignore the difference; the error because of the color space conversion is too much smaller than your loss by recompressing itself.

Originally posted by sauzan
Just wondering how the anime fansubbers did it, the quality of the subbed avi still seems pretty good I suppose they are generally recompressing the raw to hardsub it using textsub.vdf or vsfilter.dll. If the raw is HQ, even the default settings of XviD 1.0.x will be good enough. The loss by recompressing is less than you'd think and probably many ppl even don't notice it. Essentially they are HQ because the raws are HQ, and some files are not HQ because the HQ raws are not available (old anime etc). In a way, such a vid is not HQ because the fansubber (encoder) is good. Anyone can do the same thing if the raw is HQ.

However good encoders know how to 'directly' hardsub without recompressing, too. That is only possible when you have a 'lossless' source (DVD itself, huffyuv-captured TV...etc.) If your souce is already MPEG-4 compressed in AVI, you have no choice but to recompress and hardsub it (or softsub it wihout recompressing). Furthermore, in some cases, great effort has been poured to fix the problematic raw--NR, fixing frames that are wronly IVTCed, color correction, and even frame-by-frame manual retouching. That is not what anyone can do, but you can make a decent hardsub using a bad raw--Paradoxically the recompressed one might look better than the original raw.

[chipzoller]

Yes, I just did some looking after my last post and remembered you can't invoke filters on a fast recompress operation, so as Lisachan suggested, you must softsub the subtitles if you don't want to recode.

Personally, I would recode the thing with hardcoded subs and choose an acceptable amount of loss (which can be small or large) but if done on animation it usually is very small.

[Nimo]

Excuse me, I'm not sure i understand it correctly.

This full-processing are about hardsub a compressed video by one-time encoding? (not hardsub by using 2-pass encoding?)

For example
If i have compressed avi(XviD) and subtitle separately. And i want to hardsub it. (using origin codec)

- Is it possible to hardsub it with one-time encoding? (If my origin video is HQ and i don't want to 2-pass encoding again, also i want to preserve a file size, quality ...)

[chipzoller]

You have no choice. You must re-encode using Full Processing mode running a 2-pass encode. This is because those subtitles need to be converted into frame data and thus requires those selected frames to be recalculated etc. etc.

I'm not sure if submux can do the muliplexing with an xvid video...but then again, I'm no expert.


Chip

[Cyberman]

Originally posted by chipzoller
You have no choice. You must re-encode using Full Processing mode running a 2-pass encode.

Huh? Why is a 2Pass encode mandatory?

[Liisachan]

Ofcos 1-pass works fine with both Fast recompress and Full recompress. Obvious.

[chipzoller]

Oh, my mistake.

[Nimo]

So, It look like there're no way to hardsub without lossing quality and consume more file size using 1-pass. Right?
So sad... :(

This is because those subtitles need to be converted into frame data and thus requires those selected frames to be recalculated etc. etc.
But I think most subtitle are static element which is not effect the motion too much....
Anyway it just a hypothesis. Video encoding should be more complicate than i though!

[Liisachan]

No, you can use 2pass too. The loss is probably less than you think.
Most of what you think HQ vids are also recompressed from the MPEG-2.

So, enough theory. Try it out and check the result with your own eyes.

[Cyberman]

Originally posted by Nimo
But I think most subtitle are static element which is not effect the motion too much....
Anyway it just a hypothesis. Video encoding should be more complicate than i though!

The subs may be static, but the background often isn´t. Even so, they provide lots of sharp edges which are hard to encode and require tons of bitrate.