Tvheadend

Unless you have specifically configured TVHeadend to 'drop' the subtitles they are enabled by default - TVHeadend simply passes through (or re-encodes) the whole transport stream so it's up to the client to decode the subtitle data.

Which stream profile are you using? If it's HTSP then subtitles are passed through by default (no way to change this).
If it's anything else, from the TVHeadend webui, switch to the Configuration > Stream > Stream Profiles tab, pick the relevant stream profile and ensure that 'Subtitle codec' is set to 'Copy codec type'.

If that's all correct then it may simply be;
The program you are watching does not have subtitles (see below)
The format of the subtitles in the program you are watching isn't supported by the client

To check if there are subtitles in your current stream:
Go to Configuration > DVB Inputs > Services, filter the 'Channel' column by the channel that you are trying to watch, click the 'i' icon and ensure that the BOTTOM section of the screen has at least one TELETEXT or TEXTSUB entry.

Sometimes though, the combination of container, codec, subtitle and player just doesn't work. For example, TVHClient on my iPhone doesn't support DVB subtitles when used in a matroska container format.

Hi Jonathan Thomson and thank you for your reply.

My default profil is pass, and when I go to see Services detail about channel I see this.
Can you say me what is mean.

"und" just means the subtitle language is undefined, it's not generally an indication of a problem.

I've just tried streaming a channel that I know uses the DVBSUB format in VLC and it worked fine but I was using the "pass" streaming profile. Which profile are you using (for streaming - you said "pass" above, is that the name of the streaming profile you are using)? If I use a profile that uses MKV then DVBSUB subtitles do not work.

Are you getting any error messages when trying to select the subtitles track? When using VLC it complains about an unknown video or audio codec if I choose subtitles when using an MKV profile.

Does VLC even recognise that there are subtitles available? (In the menu on the desktop version or on the mobile version the subtitle button is only displayed when there are subtitles available).

Hi Jonathan Thomason. I use pass streaming profil and when I change this profil in htsp stream stop wrok.
On subtitle stream filters I setup DVBSUB but doesnt work.

Now I have subtitle on channel but I must turn on in VLC just as yo sadi.. Can you tell me my friend can it be posible auto turn on subtitle.

Kuribo Kuribo wrote:

Now I have subtitle on channel but I must turn on in VLC just as yo sadi.. Can you tell me my friend can it be posible auto turn on subtitle.

If you enable subs in VLC they should automatically stay enabled until you disable it again (unless there is no sub available).

I'm at a bit of a loss then - if you're using the 'pass' streaming profile then the whole transport stream is passed through to the client - so if there are subtitles in the stream, and that subtitle format is supported by the client, then the client will be able display those subtitles.

The stream filter on the subtitles confuses things a bit as not every provider uses the DVBSUB subtitles - so by selecting those exclusively (which is what I presume you are doing) you will get no subtitles if the provider uses teletext subtitles (TEXTSUB).

And when I use MKV (matorska) prifle and when play stream in VLC I have error on start stream in VLC.
Error is: audio or video codec not recognize.

VLC does not support DVBSUB subtitles in an MKV container (as per my post above)