The ultimate problem with subtitles in OGM

[marc_albero]

Hi you all, encoding family

I have more problems with subtitles in OGM. I have found a thread that treated the issue, but it ended 2 mounths ago without giving any solution (as far as I know).

I decided to reexplain the issue and to try to get the clever people think a little.

The problem is as follows:

I mux audio and video directly from an AVI with Oggmux 0.8.5 or Graphedit (Vorbis implementation 0.9.9.1 and Subtitle iplementation 1.1.2.2).

I give to Oggmux just the name of the avi in the video stream input, and it muxes audio and video (no audio file is given nor needed, though Oggmux complains a little before it starts muxing). As for the Graphedit way, I simply add two file readers pointing to the very same avi file. From one I take the video. From the other just the audio.

This 2 methods work flawlessly as long as no subtitle is involved. The resulting file plays everywhere. I even remember having muxed 2 audio streams in the past and everything worked right.

I try with subtitles: they were all converted to SRT format With Subtitle Studio. I don't suppose any problem with a wrong conversion. At least, Waldvogel's subtitle parser doesn't complain. There are 6 subtitle streams. I use the sub parser and the OGG muxer to generate an ogm file.

The resulting ogm doesn't play. With BSPlayer no image is generated. The time slider doesn't advance, nor does the time counter. The play button is pressed, but the film doesn't advance. The screen is black (the first frame?). The same with Windoes Media Player, but if you move the slider you see a still picture at that position of the movie. The film doesn't advance. No subtitles are showed (but they can be chosen in the menu).

I render the ogm file in graphedit and it plays right (well, the aspect ratio is all wrong, no means of full screening, subtitles are far too big... but it plays right). As for the OGG filters: the splitter enables always all the streams, which are available for displaying upon changing the graph connections. I have tried to play disabling that option under WMP, but nothing happened. I have also tried to disable those HTML tags in the sub mixer, but nothing happened. There aren't other buttons to play around with. I confess I haven't changed the font size, but I don't think it would solve the situation and make the players start playing the ogm...

(NOTE: I use WMP6.4 and BSPlayer 0.85 Build 484)

I try again with only 3 subtitles. The same problems appear.

All this happens with both methods: Oggmux and Graphedit.

So: a muxing problem or a player incompatibility issue? I don't know.

-Are there new versions of the OGG filters/OggMux I should use?

-Are there any settings in BSPlayer or WMP which will solve the issue?

-What should I do? I supposed OGM was designed to include subtitles without problems! It's a bit deceiving... :-(

[Koepi]

Sounds to me like your subtitle files might be broken.

Did you look if the timestamps are allright, and not all 00:00:00.000?
Did you take a look if the HTML tags are supported by SubDS from Tobias? He doesn't support the whole html palette...

I've no problems until now, every time I test this stuff it only doesn't work if some timestamps are broken or unsupported html TAGs are in those files.

I hope this helps.

Regards,
Koepi

[marc_albero]

I had forgotten it.

The audio stream of the AVI file was VBR mp3 (ca. 128kbps)

Is there any way to encapsulate MP3 with Vorbis header and all that?

@ Koepi : What does "broken" mean? I guess you mean that a line doesn't start before another line has ended. Yes, that surely happens. I downloaded the subs from a webpage and they are far from being perfect. In fact I remember having muxed subs from a DVD rip (which were perfect), and I think they worked good... Can it be the reason to stop the playback?

As far as I know the format is respected (if not, the parser should reject it)

[marc_albero]

What are the html tags.... I am newbie...

[Taranli Maren]

<b>bold</b>
<i>italics</i>
<u>underline</u>

These are the only ones that I'm sure work. These tags still don't work in vobsub, so I always strip them anyways.

I would also recommend converting the vbr mp3 to vorbis. There will be very little loss of quality if you maintain a decent bitrate, and it will mux and play back much better. Headac3he I believe can convert from mp3 to vorbis.

[triffid]

I had the same problem, and I believe it has to do with conflicts between directvobsub and the Ogg Subtitle Mixer DS filters. DVobsub always wants to play Ogg subtitles, especially if Morgan is involved (Morgan Stream Switcher also seems to want to take over with OGM files). I believe that with Morgan Stream Switcher and Dvobsub, there were weird problems, and without Morgan and with Dvobsub more problems, and without DVobsub and with Morgan there were other problems. One of them was the one you mentioned. I have uninstalled Morgan Stream Switcher and Direct VobSub, and everything is fine. However, this isnt really an acceptable solution as it cripples playback of multi-track AVIs, and I assume subtitle playback with AVIs will be crippled as well. Is there any sort of fix that allow Dvobsub, Morgan, and the Ogg filters to coexist without trying to do eachother's jobs? That would be a real solution to problems lots of people have been having with the OGM format.

Thanks in advance
-triffid

[Koepi]

Well, as long as the vbr mp3 is muxed with the avi already it shouldn't make any problems except for that you can't enter which language the stream has within oggmux, you'd need to use graphedit for that.

But finally, we tracked your problem down to "broken" srt subtitle files, which is good, as I don't need to scratch my head that bad that I loose hair anymore ;)

Regards,
Koepi

P.S.: just open your subtitle files with notepad, it should look like this:

1
00:02:15,807 --> 00:02:17,604
Someone better call the police.

2
00:03:38,247 --> 00:03:39,885
There was a bombing at the
U.S. embassy.

[buba king]

Again kinda OT..

(when) will The OggDS support Uncompressed (or even better, compressed) sub images? so i dont have to use OCR (witch sucks in some cases with very "1337" subs) :devil:

[marc_albero]

I haven't installed morgan nor dVobSub.

@Koepi: can you explain why those errors in the subtitle timing lead to that big playback problem? Why is OGM so sensible? BSPlayer can deal with that errors, why OGM not?

By the way:

1
00:02:15,807 --> 00:02:17,604
Someone better call the police.

2
00:03:38,247 --> 00:03:39,885
There was a bombing at the
U.S. embassy.

I can't see any problem in this subtitle sample. It should look like this:

1
00:02:15,807 --> 00:02:17,604
Someone better call the police.

2 HERE!
00:05:38,247 --> 00:03:39,885
There was a bombing at the
U.S. embassy.

That's what you find tipically.

What can I do to detect automatically those kind of errors in a SRT file and fix them? Is there any utility to do that?

Once the subs are fixed, will the VBR mp3 audio track give any problem? Have you ever tried to mux in such a scenario?
(I don't want to reencode. The audio quality stays on the border of acceptable quality, so, muxing with BR mp3 is necessary)

[Koepi]

WHY are the filters so sensible?

Well, simply because a timing-information like you showed there are WRONG - where to show that subtitle?

And if you want to automatically repair them - write an intelligent program that does it.