Subtitle error when playing streams

ben barker

Afternoon

I have found that, when playing DVB-T Freeview TV streams directly using the URLs from the playlist of the form:

http://192.168.1.1:9981/stream/channelid/1214818065?ticket=4F272A00EE655D3E59231748D73F7EC558445800

Both VLC and Totem initially return an error:

"application/x-subtitle-unknown decoder"

Which I need to clear down before the stream will play. I have so far been unable either to suppress this message, or to install whatever plugins those programs are expecting to make the error not appear in the first place.

Any ideas where this message is from, and how it can be avoided?

ProfYaffle

What version of tvheadend are you running? I guess you're using 3.4ish by the URL format, yes? I just tested streaming QUEST from 3.9.438 to VLC 2.1.3 on Win8.1 and had no such problem.

What I did notice, though, is that the subtitle stream comes through as dvbs/English if I use a passthrough (.ts) container, but changes format and language to 'undef' if I use mkv. So see if that's related... I presume (I haven't looked) that tvheadend is creating a file/buffer and relaying it to VLC, and the format of that file/buffer is determined by the recording options.

ben barker

Hi - I think you are onto something

I hadn't realised that the recording section also affected how live video was streamed.

When using the raw TS the subtitles identiffy in VLC as type "teletext" and I can view them (or not) as normal

When using MKV, they identify as "undf" when I look at the codec properties

ProfYaffle

I'd suggest you use .ts then and pretend you never saw anything :p

The mkv container option is a great idea, as I much prefer it to anything else, but I abandoned it some time ago because of various quirks and issues. Unless you really need to use it, I'd genuinely recommend looking at .ts as a default, it's less troublesome.

That said, .ts can sometimes have issues of its own because the passthrough means the streams are saved along with any timing errors, which remuxing at source seemed to cure for me. Not really a problem unless you want to edit the file.

Eric Valette

This is an vlc problem not tvheadend. Matroska format now supports S_DVBSUB streams, that is why XBMC and ffmpeg can play thoses files just fine. There is however a real mkv encoding problem as the actual code does not correctly find start code correctly and thus does not encode fourcc/isom correctly.

Eric Valette

I just added a pull request for the mkv generation that you can test

ben barker

Thanks - I found the problem both with VLC and with Totem - presumably though they share some of the same code under the bonnet - ffmpeg?

As noted above, using TS seems to work fine. Happy to test something if you think you have found a/the problem :-)

Eric Valette

ben barker wrote:
> Thanks - I found the problem both with VLC and with Totem - presumably though they share some of the same code under the bonnet - ffmpeg?
>

> As noted above, using TS seems to work fine. Happy to test something if you think you have found a/the problem :-)

For streaming TS is fine, for recording this is quite a bad idea. The fix is not for the S_DVBSUB streams but for h264 streams.