Calculate Subtitle Synchronizaiton

[lomaidala]

I used SubRip to extract an SRT file from a DVD, but the subtitles are out of sync.

It's quite easy to find guides that explain how to change the timing of subtitles, but what I haven't been able to find is how to calculate exactly how much the synchronization is off by.

Anyone know how to do this?

[pearlblack15]

Use Subtitle Edit and follow the following guide. It should help you syn your subs to the video

https://www.videohelp.com/guides/how-to-sync-a-subtitle-using-subtitle-edit-id1264#1264

[lomaidala]

Thanks, but this seems to be a method for manually adjusting subtitle timing by ear, line by line. Does anyone know how to view the timestamps of original DVD subtitles? If I could see the exact start and end times of just the first and last subtitles, I think I'd be set.

[manono]

Does anyone know how to view the timestamps of original DVD subtitles?

You can extract the VobSubs and have a look at the IDX which has all the timestamps. VobSub Configure, part of the VobSub package, can do it, among other apps.

I wouldn't think the two sets of times would be significantly different, though.

[videobruger]

@iomadala

Take you time to learn SubTitleEdit. Instead of the guide above why don't you try the "Visual Sync" and see if that solve your problem. And BTW it'll OCR a SRT file from idx/vobsub (or DVD) as well.

[lomaidala]

Thanks manono, but when I extract the IDX and SUB files using VobSub Configure, copy the timestamps from the first and last subtitles into my SRT file, and load it into the video, the subtitles are out of sync -- much more so for the last subtitle.

Thanks for the recommendation, videobruger. I'll keep Subtitle Edit in mind if no one here has solutions for the current software being used.

[manono]

...but when I extract the IDX and SUB files using VobSub Configure, copy the timestamps from the first and last subtitles into my SRT file, and load it into the video, the subtitles are out of sync -- much more so for the last subtitle.

Then, as I suspected from the beginning, the decrypt probably wasn't complete. VobSubs do contain the original timings. They're the DVD subs. Is this a newish film with newish copy protection? And how did you decrypt the DVD to the hard drive? In any event, I don't find it at all difficult to redo timings if for some reason they're off. It's not as if they have to be correct down to the last millisecond. Many professional subbers these days actually have the subs begin slightly before the talking. Even audio most people can't tell is off if it's within 100ms or so.

[lomaidala]

Thanks again, manono. The DVD is from 2001 and I ripped it using DVD Shrink. I re-authored it to only include the main title, one audio track, and the subtitles. No compression.

What you're saying would make perfect sense, only the original DVD subtitles do play perfectly. It's only when I rip to SRT or copy timing to SRT that they go out of sync.

[manono]

What you're saying would make perfect sense, only the original DVD subtitles do play perfectly.

Now I don't understand. You're saying the subs play in-synch when you play the DVD, right? If so, then sure, of course they do. And are you also saying the VobSubs are slightly out-of-synch when they're played? Or only after conversion to SRT? Me, I'd have trouble believing the VobSubs are OK, but not the SRTs made from those same VOBSubs.

Another thing you can do is to extract the SUP files from the DVD using PGCDemux. Then open them in SubtitleCreator and check the timestamps. They should be the same as those for the VobSubs.

And while in PGCDemux, tick 'Single'Cell' to check if you have unreferenced cells that might be throwing off the sub timings. They will be real short, 0.12 or 0.15 of a second.

What are you doing with the video? Reencoding it for DVD or MKV perhaps? Are SRTs necessary, or can you use the original graphic-based subs or perhaps SSA or ASS subs?

[lomaidala]

The subs play in-synch when I play both the DVD and the ripped version on my hard drive. How do I play VobSubs?

With PgcDemux, I extracted the subs by PGC rather than by VOB id because none of the VIDs looked long enough to be the entire video. Looking at the subtitles in SubtitleCreator, the timestamps are different from the VobSubs! Selecting "Single Cell" in PgcDemux does display some very short ones, several of them only 0.15 of a second.

What I'm doing with the video is creating an alternate translation for the subtitles. The end result I want to have is a universally playable video with subtitles that I can show my friends over at their places.

The first thing I thought of was to burn to DVD video, since virtually everyone can play DVDs. But once I realized it would cost me 9 blank DVDs to do this (because it's a TV series), I started thinking about alternate methods.

What I'm thinking of doing now is converting the videos to AVIs with SRTs to cut down on the number of discs required, or maybe to just abandon discs altogether and use a flashdrive instead. Any other suggestions are more than welcome, as I am a complete amateur with all this stuff.

The ASS format would actually be ideal because it's what I'm used to using in Aegisub before converting to SRT.

[manono]

The subs play in-synch when I play both the DVD and the ripped version on my hard drive. How do I play VobSubs?

You name them the same as the video they're to be played with. Movie.idx, Movie.sub, and Movie.vob (or Movie.avi), is one example.

Selecting "Single Cell" in PgcDemux does display some very short ones, several of them only 0.15 of a second.

I think that removing them would solve your problem. Those cells are a single frame but have instructions to play for longer. When played as a DVD they're fine, but when reencoded they throw off the synch because all you get is the single (probably black) frame.

I have no idea how you're making your AVI or whatever you're saying doesn't display the subs correctly, but when you mentioned DVD Shrink as your decrypter earlier I winced to myself. It's probably the reason you're having the problem you're having. I'd try again, this time using DVDFab HD Decrypter. Then check for those tiny cells. If they're still there, run the DVD through FixVTS. If they're still there after that, get rid of them all using PGCEDIT or VobBlanker.

Or just change the timings. Much easier and if you do it half decently no one, including yourself, will never know the difference. They're off by a constant amount (right?) and any number of programs can correct them. I use either SubtitleCreator or Sub Station Alpha. If the SUP file from PGCEdit has the right timings, then convert it instantly to IDX/SUB using SubtitleCreator and then OCR to SRT or whatever you like.

[lomaidala]

Selecting "Single Cell" in PgcDemux does display some very short ones, several of them only 0.15 of a second.

I think that removing them would solve your problem.

I thought I should also mention that many subtitles (about half maybe) end at 00:00:00,000 (which don't get fixed after using FixVTS). Despite this, they play fine in the original video!

I have no idea how you're making your AVI or whatever you're saying doesn't display the subs correctly

It's in the DVD format, if that's the right term (multiple Vobs in a VIDEO_TS folder) -- the one I got using DVD Shrink.

Or just change the timings. Much easier and if you do it half decently no one, including yourself, will never know the difference. They're off by a constant amount (right?) and any number of programs can correct them.

The problem with this is that it's going to take forever because of the number of episodes -- I would have approximately 10,000 subtitles to re-time. That's why I'd much rather extract the pre-existing timestamps. Plus I just don't feel confident in deciding how long to display each subtitle.

To answer your other question, the extracted subtitles are not off by a consistent amount. They are more out of synch at the end than they are at the beginning.

Since I currently don't have access to the disc I ripped that video from, I'm going to apply your instructions to a different disc (unless you want me to wait until I have access to the other disc, which I can do but it might be a while). I ripped this different DVD using two different methods: one with DVD Shrink, and the other with DVDFab HD Decrypter. The following is true in both cases:

• There are no tiny cells.
• There are no timestamps ending at 00:00:00,000.
• Timestamps are still out of synch.

However, the subtitles extracted from the version ripped with DVD Shrink seem to get progressively more out of synch as the video goes on, whereas the ones ripped with DVDFab HD Decrypter do seem to be off by a consistent amount at both the beginning and end. Also, just like with the disc I mentioned first, the subtitles play fine in the ripped video.

How do I play VobSubs?

You name them the same as the video they're to be played with.

I was able to play VobSubs with a random video my matching the file names, but not with the one in question. Does this not work if the video is spread across multiple Vobs in a VIDEO_TS folder?

Thanks again for the help!

[manono]

but what I haven't been able to find is how to calculate exactly how much the synchronization is off by.

To answer your other question, the extracted subtitles are not off by a consistent amount. They are more out of synch at the end than they are at the beginning.

Then what good would it be to find is how to calculate exactly how much the synchronization is off by? All this time I was assuming they're off by a set amount all the way through, something that's easy to fix by setting a delay in the subs.

I'm afraid I'm going to have to retire from this. Partly because I don't understand the problem. Partly because I never have and never will use DVDShrink for anything like what you're using it for (although many do). Partly because I now have no idea how to help you solve your problem.

Maybe decrypt the entire DVD to the hard drive and let AutoGK have at it. It can extract the VobSubs and then burn them into the video if you like, or you can keep them external. I only mention this because you said at one point you were thinking of making an AVI. Open the IFO in AutoGK (because you need the subs), and not the VOBs. Or get the subs from an external subtitle site, several of which are mentioned in a sticky in the Subtitles Forum here.

Good Luck.

[lomaidala]

but what I haven't been able to find is how to calculate exactly how much the synchronization is off by.

To answer your other question, the extracted subtitles are not off by a consistent amount. They are more out of synch at the end than they are at the beginning.

Then what good would it be to find is how to calculate exactly how much the synchronization is off by?

The idea I had was to copy the timestamps of the actual start and end times of the first and last subtitles, then compare them against the extracted start and end times of the first and last subtitles I obtained via OCR, and then use the difference to calculate and apply the correct timing throughout the entire extracted subtitle file using the Time Stretch / Speed Adjust feature in SubRip.

All this time I was assuming they're off by a set amount all the way through,

I think you must have assumed that because you missed this, from Post #6:

Thanks manono, but when I extract the IDX and SUB files using VobSub Configure, copy the timestamps from the first and last subtitles into my SRT file, and load it into the video, the subtitles are out of sync -- much more so for the last subtitle.

But now that I'm using DVDFab HD Decrypter instead of DVD Shrink, the timing does now seem to be off by a set amount.

that's easy to fix by setting a delay in the subs.

But how do you know how much to delay the subs by? How does one determine the exact delay?

I'm afraid I'm going to have to retire from this.

I will clarify a few things in case that changes things or in case someone else here is willing to pick up where you left off.

Partly because I don't understand the problem.

The problem is that I can't see what the actual start and end times are for any of the DVD's subtitles. What I see are timestamps that result in out of synch subtitles.

Partly because I never have and never will use DVDShrink for anything like what you're using it for (although many do).

But I'm no longer using DVDShrink! I'm now using DVDFab HD Decrypter, per your recommendation. When I mentioned DVD Shrink in my last post, it was really only something extra I added in reference to a test I did to narrow down what might be causing the issue, not to state the tool for my process.

Maybe decrypt the entire DVD to the hard drive and let AutoGK have at it. It can extract the VobSubs and then burn them into the video if you like, or you can keep them external. I only mention this because you said at one point you were thinking of making an AVI. Open the IFO in AutoGK (because you need the subs), and not the VOBs.

Thanks for the recommendation -- AutoGK seems like a useful tool. However, having ripped the disc to my hard drive using DVDFab HD Decrypter, and having converted that to avi using AutoGK, the subtitles are now part of the video, yet they are still out of synch.

The other thing that perplexes me is the range of timestamps. I get different results depending on which program I use to extract the subtitles. Here are the various timestamps for the very first subtitle.

PgcDemux
(.sup)
00:03:04:951

VobSub
(.idx)
00:03:04:868

AutoGK
(.idx)
00:03:04:934

Or get the subs from an external subtitle site, several of which are mentioned in a sticky in the Subtitles Forum here.

Unfortunately I've been unable to find any among those links with the correct timing.

Even though I still have no way of of calculating the timestamps, thanks a bunch for all the time and effort you put in to helping me.

[manono]

But now that I'm using DVDFab HD Decrypter instead of DVD Shrink, the timing does now seem to be off by a set amount.

Well, at least you're making progress.

But, in my opinion, you're being way too anal about this:

PgcDemux
(.sup)
00:03:04:951

VobSub
(.idx)
00:03:04:868

AutoGK
(.idx)
00:03:04:934

You're quibbling about the timings you get from three different apps whose greatest difference is less than 100ms - less then one tenth of a second? And two of them have a difference of 17/1000th of a second? If you wish to use the middle ones adjust the timings by maybe 0.08 and be done with it. You'll never be able to tell the difference. But maybe, although there are only minor differences between the three, in actual use the differences are much greater between the dialog and the time the subs show up? In that case, choose one of the VobSubs and set a delay.

However, having ripped the disc to my hard drive using DVDFab HD Decrypter, and having converted that to avi using AutoGK, the subtitles are now part of the video, yet they are still out of synch.

Yes, by default AutoGK burns the subs into the video. If you wish to keep them separate, go into the Advanced Settings and check the 'Use External Subtitles' box. And you can use those external subs with the AVI to determine how much the delay should be. Take a guess, change the delay for them all (I use SubtitleCreator for this), test them out, and then adjust if necessary.

[lomaidala]

You're quibbling about the timings you get from three different apps whose greatest difference is less than 100ms - less then one tenth of a second?

No, I'm just saying it's strange that they're different. I don't care at all about the difference. It's entirely possible I wouldn't be able to tell the difference. But the fact that they are different is something that I thought should be brought to the attention of this thread, in case those are signs that something's not right with either how I'm extracting the timestamps, or how the programs extract them.

Extra details like the timestamps that I added in my previous post seem to be leading you to believe that they're the focus of this thread. They are not. The point is:
Any set of timestamps I use results in subtitles that are noticeably off from the spoken dialog, and I have no way of measuring exactly how much. If there isn't a way of seeing the exact timestamps down to the millisecond, then I'm willing to live with that. But if it is possible, I'd like to know how.

Yes, by default AutoGK burns the subs into the video. If you wish to keep them separate, go into the Advanced Settings and check the 'Use External Subtitles' box.

I saw that option, but when I try it, I get this error:
"WinRAR is not found. You cannot use this option without it."

Thing is, I do have WinRAR. How do I get AutoGK to find it?

I also have a mistake to correct. While the timestamp I listed for the .idx from AutoGK was correct, it was from the 'letbox' subtitle track, not the 'wide' subtitle track. The timestamps from the 'wide' .idx are identical to the ones from the VobSub .idx. So if I'm not mistaken, that means I really have two different results for the timestamps, not three.

in my opinion, you're being way too anal about this

Some of the best work comes from anal people. I'll take that as a compliment.

[manono]

"WinRAR is not found. You cannot use this option without it."

Possibly a 32bit/64bit problem. See if this thread solves (or complicates) it for you:

http://forum.doom9.org/showthread.php?t=154468

[lomaidala]

I've figured it out! Well, almost.

A separate subtitle file (in this case, an .srt) will play out of synch if the video it's being tested with is in the VIDEO_TS format -- even if the same timestamps from the DVD are used. Testing with the VIDEO_TS seems to be what was throwing me off.

I tried out the .srt I got (using SubRip) on the AVI I got (using AutoGK) and the subtitles played almost perfectly! To reach a higher level of accuracy, I took the first and last subtitle start times in the .srt and compared them to the first and last timestamps found in the .idx, calculated the difference, then used SubRip to correct the timing in the .srt using Time Stretch. The result is the most accurate subtitles file I've been able to create thus far. But a good number of subtitles are still off by just a tiny bit. I'm wondering if this has to do with the fact that my calculations are based solely on start times.

In SubRip, how is the "total Subtitles file duration" measured when "Time Stretch" is used? I would assume the answer is "from the beginning of the first subtitle to the end of the last subtitle". If that's true, how do I see when timestamps end in the .idx file? All I see are start times.

"WinRAR is not found. You cannot use this option without it."

Possibly a 32bit/64bit problem. See if this thread solves (or complicates) it for you:

http://forum.doom9.org/showthread.php?t=154468

Thanks! I think I'll pass on it for now. It does look like it might complicate things.

[jagabo]

Your problem is the playback of the video, not the subtitles. Your VOB files use variable frame rates and many players don't handle that properly. You need to convert the video to constant frame rate. The best way to do this is to use DgIndex with Honor Pulldown Flags enabled, inverse telecine (if appropriate), then encode with a constant frame rate.

[lomaidala]

I see the Honor Pulldown Flags option, but which option encodes with a constant frame rate, and how do I know if I should inverse inverse telecine?

[manono]

I see the Honor Pulldown Flags option, but which option encodes with a constant frame rate...

Both Honor Pulldown Flags and Force Film give you constant framerates (29.97fps for the former, 23.976fps for the latter). Don't use Ignore Pulldown Flags.

...how do I know if I should inverse inverse telecine?

If it's a movie on NTSC DVD, almost always the final framerate should be 23.976fps. If you make the D2V using Honor Pulldown Flags, then it needs an IVTC. If the film percentage is very high (100% is best - look at the bottom of the D2V), then you can safely Force Film and get 23.976fps without an IVTC.

[lomaidala]

My disc is NTSC DVD, so after opening all the VOBs with DGIndex, I did this:

Video > Field Operation > Forced Film
File > Save Project and Demux Video

My percentage is pretty high; the bottom of the d2v file reads "FINISHED 99.70% FILM". I assume this means I successfully converted the video to constant frame rate, and that inverse telecine is not necessary.

How do I now encode with a constant frame rate?

[manono]

I assume this means I successfully converted the video to constant frame rate, and that inverse telecine is not necessary.

That's right. It's 23.976fps already and an IVTC isn't needed.

How do I now encode with a constant frame rate?

It's all explained in the included docs, particularly the DGDecodeQuickStart.html. You create an AviSynth script and open it (in VDub or some other encoder) just as you would any video. To quote one important paragraph:

What is This Index File and What Do I Do with It?
DGIndex created an index file called *.d2v. It is read by DGDecode, which actually decodes the MPEG and delivers the video. The index file just contains information that tells DGDecode where each frame is located and some information about each frame. But you can't just execute DGDecode directly! It has to be done through Avisynth. We'll make a script file called myvob.avs using a text editor. Later in this document I'll show you how to configure DGIndex to make the script automatically, but for now, you need to know the old-fashioned way. So put this text into a new text file you make called 'myvob.avs':

LoadPlugin("...\DGDecode.dll")
MPEG2Source("myvob.d2v")

Replace the path '...' in the first line with the path to the location where you placed DGDecode.dll.
Finally, use VirtualDub to open the 'myvob.avs' script file just as if it was an AVI file. That's it! You have your video and can navigate randomly on the VirtualDub timeline.

[lomaidala]

Thank you. I wrote a script, but I'm unable to open myvob.avs in VirtualDub due to the following error:

Avisynth open failure:
Script error: there is no function named "AC3Source"

I think this is because my audio is AC3 and I don't have the source filter for it. The link in the DGIndex guide to such filters is not working. Where should I be getting it from?

Here's my script for myvob.avs:

LoadPlugin("C:\dgmpgdec158\DGDecode.dll")
MPEG2Source("C:\DGIndex Conversion\VTS_01_1.d2v")
AC3Source("C:\DGIndex Conversion\VTS_01_1 T80 3_2ch 448Kbps DELAY -22ms.ac3")
AudioDub(video,audio)

[manono]

Why put the audio into the script? If this is for DVD then you can easily bring it back in during the authoring stage. Most MPEG-2 encoders don't handle audio anyway. If it's for something else you can mux it in later. There's no AC3Source built into AviSynth the way there is a WAVSource.

If you have to do it this way, then one solution is to get the NicAudio.dll and then use NicAC3Source.

http://www.avisynth.nl/users/warpenterprises/

Don't forget to account for that delay when muxing. Either that or remove it entirely using DelayCut.

[lomaidala]

Why put the audio into the script?

Because it seemed like the next logical step in what jagabo was recommending, but I don't really know what I'm doing. Since I'm trying to match the timing of my custom subtitles with the timing of the original DVD subtitles, I just guessed the best way to follow his advice was to encode the AVI with video and audio so I could test out my subtitles to see if the timing was any better.

If you have to do it this way,

I would like to do whichever way gives me the best results, so I guess the answer is no. Would the best next step be to encode the video without audio, then mux in the audio? The end result needs to be an AVI.

[manono]

Correct me if I'm wrong, but it seems all you care about is creating an in-synch subtitle file to add to the DVD. Your goal isn't to reencode anything, but just to have some way to synch up the subs. Is that correct?

And then afterwards you want to add the new subs to the DVD you already have? Anyway, depending on how you intend to make your AVI with audio, you can encode in VDub for XviD AVI using your script without audio and add in the separate audio at the same time in the audio section. That way you'll keep the AC3 unchanged, where using it in the script will give you back the video with a WAV file in it (unless you have VDub reencode it at the same time, maybe to MP3 audio). Again, don't ignore the delay. It's a small one, but still worth getting right.

[lomaidala]

Correct me if I'm wrong, but it seems all you care about is creating an in-synch subtitle file to add to the DVD.

Correct, except for one thing: I want to add the subtitle file to an AVI, not a DVD. The original video is from my DVD, but I want it to be an AVI. I want the timing for the AVI subtitles to exactly match the timing of the original DVD subtitles. For the particular effects I want to use (subtitles that can fade in and out), the best way I know is to embed the subtitles into the AVI, which I've done before using VirtualDub. But I'm open to any other way that would give me better results, or do the thing I'm doing but faster.

Your goal isn't to reencode anything, but just to have some way to synch up the subs. Is that correct?

I would say that's correct, although it sounds as if I will have to reencode by necessity, due to the fact that I want the end result to be an AVI. Converting a DVD to an AVI would require reencoding, right?

Anyway, depending on how you intend to make your AVI with audio,

Just whatever method gives me the best results. I'm willing to do extra work for better quality.

you can encode in VDub for XviD AVI using your script without audio and add in the separate audio at the same time in the audio section. That way you'll keep the AC3 unchanged,

Sounds great! But when I tried this, it said the file "is of an unknown or unsupported file type." What am I doing wrong? I selected the AC3 file by going to Audio > Audio from other file...

where using it in the script will give you back the video with a WAV file in it (unless you have VDub reencode it at the same time, maybe to MP3 audio).

I didn't realize that. Your suggestion for the other method sounds much better.

Again, don't ignore the delay. It's a small one, but still worth getting right.

Will I still have to adjust the delay if I keep the AC3 unchanged and add it to the audio section in VDub separately from the script? Or was that just for the script method?

[manono]

See if installing the AC3 ACM Codec allows VDub to accept AC3 audio input in Audio->Audio from other file. You can set a delay at the same time you're adding in the audio. That's in the 'Interleaving' section of Audio. The amount of the delay is in the name of the AC3 track demuxed by DGIndex, -22ms.

Oh, so it's an AVI you want. Should be easy to make. Yes, you'll be reencoding. You might want to crop and resize as at 720x480 the aspect ratio will be wrong.

I don't know how you'll be playing the AVI (computer, DVD/MPEG-4 player, WDTV, through a Roku, etc.), but you don't necessarily have to hardcode the subs into the video. They can be kept separate/external and many players can play them just fine, along with the video.

[lomaidala]

See if installing the AC3 ACM Codec allows VDub to accept AC3 audio input in Audio->Audio from other file.

I've now installed it, but I'm still getting the same error.

You might want to crop and resize as at 720x480 the aspect ratio will be wrong.

Thanks! Funny coincidence, but I actually just learned how to do this myself a few days before your post.

I don't know how you'll be playing the AVI (computer, DVD/MPEG-4 player, WDTV, through a Roku, etc.), but you don't necessarily have to hardcode the subs into the video. They can be kept separate/external and many players can play them just fine, along with the video.

That's the problem, since I'll be taking the episodes to various friends' places to show them, I don't even know how I'll be playing the AVIs! That's why I have my PlayStation 2 with Simple Media System to bring as backup. Since it has limited display options with external subtitles, I thought embedding them would be the best choice.