Tvheadend

I have noticed following issue in TV recordings: if the DVB subtitles are not present at the exact moment when a recording starts, those DVB subtitles are not included in the recording even though subtitles will appear later. So if the program starts at 19:00 and it will have DVB subtitles and your recording starts 18:59 (when the DVB subtitles are not yet sent), you will completely lose these DVB subtitles even though they are sent starting at 19:00.

This is very common here in Finland with provider YLE channels. They seem not to send DVB subtitle stream constantly but only when a program starts which has subtitles. So if the program spoken language is native Finnish, there is usually no DVBSUB stream. But if program spoken language is e.g. English, there is DVBSUB stream but it is sent only when the foreign language program starts and the DVBSUB stream continues to exist until the foreign language program ends.

Below is example from tvheadend logs how it looks like.

First log example is for recording that started one minute before the program "Vallan linnake" started (20:00 start time). This program did have DVB subtitles (Finnish and Swedish), I verified it watching live TV. But as you can see, the log does not mention the DVBSUB stream.

2019-03-14 19:58:30.000 [   INFO] dvr: About to set stop timer for "Vallan linnake (7)" on "Yle Teema & Fem HD" at start 1552586400 and original stop 1552590000 and overall stop at 1552590180
2019-03-14 19:58:30.001 [   INFO] subscription: 001D: "DVR: Vallan linnake (7)" subscribing on channel "Yle Teema & Fem HD", weight: 300, adapter: "Panasonic MN88473 : DVB-C #1 (1)", network: "Elisa", mux: "362M
Hz", provider: "YLE", service: "Yle Teema & Fem HD", profile="pass" 
2019-03-14 19:59:00.003 [   INFO] dvr: /var/media/Seagate/tv/Vallan-linnake-(7)-Yle-Teema-&-Fem-HD2019-03-14.ts from adapter: "Panasonic MN88473 : DVB-C #1 (1)", network: "Elisa", mux: "362MHz", provider: "YLE",
 service: "Yle Teema & Fem HD" 
2019-03-14 19:59:00.003 [   INFO] dvr:  #  type              lang  resolution  aspect ratio  sample rate  channels
2019-03-14 19:59:00.003 [   INFO] dvr:  1  H264                    1920x1080   ?                                    
2019-03-14 19:59:00.003 [   INFO] dvr:  2  AC3               swe                             ?            ?         
2019-03-14 19:59:00.003 [   INFO] dvr:  3  TELETEXT     

I continued recording the program for about 15 minutes, stopped recording and tried to watch it: no DVB subtitles were present.

Here is example of starting to record the same program but now recording started after 21 mins the program started (I stopped previous recording). Now you can see that the DVBSUB stream is recognized:

2019-03-14 20:21:26.937 [   INFO] dvr: "Vallan linnake (7)" on "Yle Teema & Fem HD" recorder starting
2019-03-14 20:21:26.938 [   INFO] dvr: About to set stop timer for "Vallan linnake (7)" on "Yle Teema & Fem HD" at start 1552586400 and original stop 1552590000 and overall stop at 1552590300
2019-03-14 20:21:26.938 [   INFO] mpegts: 362MHz in Elisa - tuning on Panasonic MN88473 : DVB-C #1 (1)
2019-03-14 20:21:26.938 [   INFO] subscription: 002D: "DVR: Vallan linnake (7)" subscribing on channel "Yle Teema & Fem HD", weight: 300, adapter: "Panasonic MN88473 : DVB-C #1 (1)", network: "Elisa", mux: "362M
Hz", provider: "YLE", service: "Yle Teema & Fem HD", profile="pass" 
2019-03-14 20:21:27.628 [   INFO] dvr: /var/media/Seagate/tv/Vallan-linnake-(7)-Yle-Teema-&-Fem-HD2019-03-14.ts from adapter: "Panasonic MN88473 : DVB-C #1 (1)", network: "Elisa", mux: "362MHz", provider: "YLE",
 service: "Yle Teema & Fem HD" 
2019-03-14 20:21:27.628 [   INFO] dvr:  #  type              lang  resolution  aspect ratio  sample rate  channels
2019-03-14 20:21:27.628 [   INFO] dvr:  1  H264                    1920x1080   ?                                    
2019-03-14 20:21:27.628 [   INFO] dvr:  2  AC3               dan                             ?            ?         
2019-03-14 20:21:27.628 [   INFO] dvr:  3  TELETEXT                                                                 
2019-03-14 20:21:27.628 [   INFO] dvr:  4  AC3               dut                             ?            ?         
2019-03-14 20:21:27.628 [   INFO] dvr:  5  DVBSUB            fin                                                    
2019-03-14 20:21:27.628 [   INFO] dvr:  6  DVBSUB            swe   

I again continued recording the program for about 15 minutes, stopped recording and tried to watch it: now DVB subtitles were present as expected.

This is really annoying because to fix this at the moment, you can not start the recording at the time the program starts but maybe like 1 minute after to be sure that the DVBSUB stream is present when the recording starts. But this is no good solution because you will loose that 1 minute at the beginning of the recording.

This seems to be same issue that was supposed to be fixed in issue #4538

I assume that previously tvheadend did recognize that the stream DVBSUB is changed and then it created a new *.ts file but now it seems not to do this.

I have tried this with this setup: Raspberry Pi 3 with LibreElec 9.0.1 running tvheadend, kernel 4.19.23. I tried LibreElec tvheadend server versions:

• Build: 4.2.7-44 ~ LibreELEC Tvh-addon v9.0.118
• HTS Tvheadend 4.3-1774 ~ LibreELEC Tvh-addon v9.0.444
• HTS Tvheadend 4.2.4-23 ~ LibreELEC Tvh-addon v9.0.113

None of those versions worked (all were missing DVBSUB stream in recordings as described above).

Strange thing is that not even downgrading to version Tvheadend 4.2.4-23 (where this issue #4538 was fixed) did not help anymore. I am quite sure that this was working previously with version 4.2.4-23 but then I had probably different version of LibreElec with different kernel version (can not remember the exact version). So it seems that the kernel version might affect this also.