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Lars Andersen

Subtitle missing

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Lars Andersen

Hi,

I really hope someone could help me with this one. I'running Media Server 2.1.5.1 and have subtitles on all my IPTV channels except cmore channels.

All other channels seems ok and subtitles show up in DVBViewer pro and kodi.

I have downloaded VLC player and started a cmore stream and VLC shows the subtitle! So I knows it is included in the stream.

I hope I'm just missing a setting somewhere but I simply can not find it. I believe I have enabled everything I could find (teletext, dvbsubtitles).

Let me know if I need to upload a log file. Then I will try to do that.

 

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Griga

What type of IPTV is it? How do the URLs look like? Can you provide an example?

 

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Lars Andersen

Hi again,

 

Thanks for looking into it.

 

More info comes here. I have placed my url in transedit now and you can see result in the screenshot.

So we are talking teletext. When I choose Preview it is possible to see the different Subtitles. But even when I select them they do not show up in the picture. Nothing?

I know for sure it is working within the VLC player. 

2019-09-11_10-30-40.png

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Griga

Can you upload a sample somewhere? Best would be to record it with TransEdit while teletext subtitles are active:

  • Right-click the PID list in the Analyzer -> Select All.
  • Click Start Recording -> wait about 30 seconds -> Click Stop Recording
  • Settings -> Analyzer -> Output Directory tells you where the target directory is.

You may also want to inspect the teletext data by right-clicking the teletext stream in the PID list -> Teletext/Subtitle Analyzer. Data that is flagged as subtitle page should be displayed like this:

 

Zwischenablage01.png

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Griga

Looks like they are doing some non-standard stuff.... DVBViewer and TransEdit expect the teletext data packets to begin at a fixed offset. The stream does not comply with it. However, it is not so difficult to calculate the variable offset. This looks better now:

 

Zwischenablage01.png

 

But I don't understand why there is a hex page number 1FF. According to the PMT content it should be 199. Usually pages with hex digits are not intended to be visible for television viewers. And why is the page not flagged as subtitle page? Further investigations are required... do you have a TV set where you can look up the page numbers?

 

If I can make it work, you will have to test an updated DVBViewer version... so stay tuned :)

 

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Lars Andersen

This is very good news so far!

I hope your investigations will bring some lights on what is going on here because I cannot answer those questions. Very strange with the page numbers.

Unfortunately I don't have a TV to look up the page numbers.

 

I'm ready to test an updated version anytime 🙂

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Griga

If you want to inform your provider about the matter: The teletext stream violates the DVB specifications in ETSI EN 300 472, 4.1 Transport Stream (TS) packet format:

 

Zitat

The standard TS packet syntax and semantics are followed, noting the following constraint:
adaptation_field_control:  only the values "01" and "10" are permitted.

 

The stream uses the forbidden value "11" for adaptation_field_control.

 

This shifts the beginning of the teletext data within the transport stream packets to a non-standard position, so that the teletext data packets are no more aligned with the transport stream packets and get fragmented. Handling it requires additional buffering (including loss of some efficiency), though 99,99% of the DVBViewer users don't need it.

 

Anyway, it was an interesting task to find out why the subtitles don't work in DVBViewer... please check your PMs.

 

The video and the subtitles seem to be a bit out of sync. The subtitles are displayed too early (same in VLC). Is it normal for this broadcaster?

 

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Hansrh

Cmore usually uses DVB-subtitles and not Teletext, at least here in Sweden.

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Lars Andersen

Yes, it is working with subtitles now in the updated version. But as you mention the subtitles is coming a little to soon. This not good.

This seems to be the case for all the channels from canal digital (c more) now.

My provider has also viasat channels and there is no subtitle problems. But they are not teletext and seems to be "hardcoded" in the video.

Another thing is that I'm using Kodi as my front end and there is no subtitles there. Arrrrg. Because they have their own player I guess that also cannot handle this bad teletext.

 

I'm in the middle of migrating away from MediaPortal with ArgusTV as recording backend. I used satellite dish with ArgusTV.

I still have the setup running and have test recorded this movie "Friday light..." from satellite.

https://onedrive.live.com/?authkey=!AOyIk-SGZJQ5my0&id=ABDDB4C99536A12!18886&cid=0ABDDB4C99536A12

Subtitles is ok and also the timing. Maybe you can use it for getting more info.....

 

I'm trying to build a perfect IPTV setup and has chosen DVBViewer (Media server) and Kodi. I'm so close to keep the wife happy if I can get the c more subtitles working in Kodi.

Any suggestions are very welcome! 

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Griga
vor 9 Stunden schrieb Lars Andersen:

But as you mention the subtitles is coming a little to soon. This not good.

This seems to be the case for all the channels from canal digital (c more) now.

 

Whoever configured the Cmore teletext subtitle encoder did a bad job. Video, audio and subtitles are broadcasted with PTS (Presentation Time Stamps) that specify when it is output relative to each other. Of course DVBViewer (and also VLC, I guess) reads the PTS and takes them into account. If the PTS are wrong, there is not much we can do about it.

 

Maybe a setting that allows for manual adjustment by shifting the subtitle PTS x milliseconds to the future/past would help. The Cmore sample needs a 2500 ms subtitle delay (just tried by hardcoding it). However, you would need to change such a global setting every time after switching between channels with/without/with another sync issue, because they would all be affected. Making it a "per channel" setting would entail quite some work for developers and users.

 

VLC has a such a setting (tools -> track synchronization), that is automatically reset to 0 when the video stops. However, it doesn't seem to take effect on the Cmore sample. Or can you make it work?

 

vor 9 Stunden schrieb Lars Andersen:

Another thing is that I'm using Kodi as my front end and there is no subtitles there.

 

Posting  it in the Kodi forum (and providing a sample as well) may be more promising... or even better, writing to the provider, as already suggested above, and telling him, how troublesome the subtitles are. Things like that should be fixed at the source, not by work-arounds in all kinds of client software.

 

vor 9 Stunden schrieb Lars Andersen:

I still have the setup running and have test recorded this movie "Friday light..." from satellite.

 

The sample contains graphical DVB subtitles, no (tele)text based subtitles. That's something different. You can see it in the TransEdit Analyzer. Simply drag & drop the file into the TransEdit main window.

 

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