Missing DVB-T subtitles

[Caesium]

Hi

Using Linux server with the latest stable zip distribution, just downloaded today.

I'm having a problem with DVB-T subtitles not always being rendered. This is both in the Kodi client and in VLC. I noticed it was reproduceable on a certain channel so I made a quick recording of a channel that doesn't show the subtitles, and then one that does. There's some differences in the streams in the files.

This one from BBC1 HD doesn't render subtitles, even though they're present:

Code:

Input #0, mpegts, from 'Pointless/Pointless_20220218_17151800-1.ts':
  Duration: 00:00:14.94, start: 92460.293756, bitrate: 2685 kb/s
  Program 17540
    Stream #0:0[0x19c9]: Video: h264 (High) ([27][0][0][0] / 0x001B), yuv420p(tv, bt709, top first), 1920x1080 [SAR 1:1 DAR 16:9], 25 fps, 25 tbr, 90k tbn, 50 tbc
    Stream #0:1[0x19ca](eng): Audio: aac_latm (LC) ([17][0][0][0] / 0x0011), 48000 Hz, stereo, fltp
    Stream #0:2[0x19ce](eng): Unknown: none ([17][0][0][0] / 0x0011) (visual impaired) (descriptions) (dependent)
    Stream #0:3[0x19cd](eng): Subtitle: dvb_subtitle ([6][0][0][0] / 0x0006)
    Stream #0:4[0x1c86]: Unknown: none ([11][0][0][0] / 0x000B)
    Stream #0:5[0x1c97]: Unknown: none ([11][0][0][0] / 0x000B)
    Stream #0:6[0x1bc4]: Unknown: none ([5][0][0][0] / 0x0005)
    Stream #0:7[0x1bc6]: Unknown: none ([5][0][0][0] / 0x0005)

This one from ITV1 HD renders them fine:

Code:

Input #0, mpegts, from 'The Chase/Season 15/The.Chase.S15E09.ts':
  Duration: 00:00:10.12, start: 91602.102189, bitrate: 3350 kb/s
  Program 17603
    Stream #0:0[0xc9]: Video: h264 (High) ([27][0][0][0] / 0x001B), yuv420p(tv, bt709, top first), 1920x1080 [SAR 1:1 DAR 16:9], 25 fps, 25 tbr, 90k tbn, 50 tbc
    Stream #0:1[0xca](eng): Audio: aac_latm (LC) ([17][0][0][0] / 0x0011), 48000 Hz, stereo, fltp
    Stream #0:2[0xce](eng): Unknown: none ([17][0][0][0] / 0x0011) (visual impaired) (descriptions) (dependent)
    Stream #0:3[0xcd](eng): Subtitle: dvb_subtitle ([6][0][0][0] / 0x0006)

I don't know if the unknown streams are confusing the players, or what. I can share these TS files if it would help, they're only a few seconds long but long enough to demonstrate the problem.

I also have the tuner log from tuning these channels, see device-adapter2.log. In this file, at 18:05:41 is tuning to a channel that doesn't show any subtitles. Then at 18:06:34 tuning to one that does.

I did notice that the subtitle pid (PID 6605 / 0x19CD, as per the first paste above) isn't mapped on the first tune, but it is on the second tune (PID 205 / 0xCD). But they both seem to end up in the output file anyway.

Anyway before I ramble on too much more, anyone any idea what might be going on? Very happy to do any debugging requested!

[mvallevand]

NextPVR delivers the stream unfiltered to Kodi and VLC so this would not be a NextPVR problem. For recordings you might be able to remux them to remove those garbase Unnknown streams that do cause some players to have issues.

Martin

[Caesium]

Hey Martin,

Thanks for looking at this. I dug a bit deeper into my recorded files and I'm not really sure if NextPVR is passing through the contents of the dvb subtitle PID? It seems like the PIDs are in the PAT/PMT/whatever (my MPEG-TS is rusty) but then there's no actual content in PID 6605 in my Pointless file. There is content in PID 205 of The Chase, which makes sense as that one displays fine.

To determine this I just used a free Windows utility; https://github.com/daniep01/MPEG-2-Trans...t-Analyser

I've attached a screenshot of analysis of both the above files.

Is it possible that packets for the relevant PID aren't being passed through? The extra streams might be a bit of a red herring. Not sure how to debug this further yet..

I've put the files up here in case you're able to work anything out from them..

https://www.cae.me.uk/tmp/Pointless_2022...51800-1.ts
https://www.cae.me.uk/tmp/The.Chase.S15E09.ts

[Edit: repost for smaller screenshots]

[sub]

NextPVR is recording all the streams that are broadcast for a channel. It's not filtering them in any way. It's likely some shortcoming in whatever player you're using.

Those files are too short to properly test them here, but I can see NextPVR is reporting that DVB Subtitles is available in both.

[Caesium]

Here's a slightly longer test file, if you don't mind just trying that? https://www.cae.me.uk/tmp/bbc2_today_at_the_games.ts

I'm pretty sure I'm not seeing subtitle packets in it

From ffmpeg in this one;

Code:

  Program 17472
    Stream #0:0[0x65]: Video: h264 (High) ([27][0][0][0] / 0x001B), yuv420p(tv, bt709, top first), 1920x1080 [SAR 1:1 DAR 16:9], 25 fps, 25 tbr, 90k tbn, 50 tbc
    Stream #0:1[0x66](eng): Audio: aac_latm (LC) ([17][0][0][0] / 0x0011), 48000 Hz, 5.1, fltp
    Stream #0:2[0x6a](eng): Unknown: none ([17][0][0][0] / 0x0011) (visual impaired) (descriptions) (dependent)
    Stream #0:3[0x69](eng): Subtitle: dvb_subtitle ([6][0][0][0] / 0x0006)
    Stream #0:4[0x1c86]: Unknown: none ([11][0][0][0] / 0x000B)
    Stream #0:5[0x1c97]: Unknown: none ([11][0][0][0] / 0x000B)
    Stream #0:6[0x1bc4]: Unknown: none ([5][0][0][0] / 0x0005)
    Stream #0:7[0x1bc6]: Unknown: none ([5][0][0][0] / 0x0005)

So it should be PID 105 / 0x69, but MPEG-2 Analyser isn't showing any content in that PID. Not quite sure what's going on.. The players I'm trying are Kodi and VLC. I'll see if I can find another player to try

[mvallevand]

Since this is a Kodi problem, you need to look at upload the zipped Kodi debug logs. That sample doesn't look like it has dvb subtitles though.

Martin

[sub]

If you're in a position to capture a 1 minute full transport stream, and put it somewhere like onedrive / googledrive, then I'll double check with my signal generate what happens when recording this content.

Things work slightly differently on Linux, and while I'm 90% sure all the streams are included, there is the slightest possibility the stream isn't being included. A sample would allow me to check what happens at recording start.

[Caesium]

Hi Sub,

Yep no problem - I've put it on my server here: https://www.cae.me.uk/tmp/mux.ts (270MB)

This is the entire mux, so there's a few channels in it (dump at the bottom of post). I think the only problematic ones are BBC1 HD and BBC2 HD, the others seem ok?

Just to confirm, I did this:

Code:

# dvbv5-zap -c scan-rowridge -I DVBV5  "BBC TWO HD" -r
using demux 'dvb0.demux0'
reading channels from file '/srv/media/nextpvr/scan-rowridge'
service has pid type 05:  7110 7108
tuning to 474167000 Hz
video pid 101
  dvb_set_pesfilter 101
dvb_dev_set_bufsize: buffer set to 6160384
audio pid 102
  dvb_set_pesfilter 102
      (0x00)
Lock  (0x1f) Signal= -40.00dBm C/N= 37.75dB UCB= 66 postBER= 0
  Layer A: C/N= 75.57%
Lock  (0x1f) Signal= -40.00dBm C/N= 37.75dB UCB= 66 postBER= 0
  Layer A: C/N= 75.57%
DVR interface '/dev/dvb/adapter0/dvr0' can now be opened
Lock  (0x1f) Signal= -40.00dBm C/N= 37.75dB UCB= 66 postBER= 0
  Layer A: C/N= 75.57%
^CLock  (0x1f) Signal= -40.00dBm C/N= 37.75dB UCB= 66 postBER= 0
  Layer A: C/N= 75.57%

And then this for a minute:

Code:

dvbsnoop -s ts -tsraw -b > mux.ts

Code:

  Duration: 00:00:57.77, start: 4467.040856, bitrate: 39330 kb/s
  Program 17472
    Metadata:
      service_name    : BBC TWO HD
      service_provider:
    Stream #0:7[0x65]: Video: h264 (High) ([27][0][0][0] / 0x001B), yuv420p(tv, bt709, top first), 1920x1080 [SAR 1:1 DAR 16:9], 25 fps, 25 tbr, 90k tbn, 50 tbc
    Stream #0:8[0x66](eng): Audio: aac_latm (LC) ([17][0][0][0] / 0x0011), 48000 Hz, 5.1, fltp
    Stream #0:9[0x6a](eng): Unknown: none ([17][0][0][0] / 0x0011) (visual impaired) (descriptions) (dependent)
    Stream #0:10[0x69](eng): Subtitle: dvb_subtitle ([6][0][0][0] / 0x0006)
    Stream #0:5[0x1c86]: Unknown: none ([11][0][0][0] / 0x000B)
    Stream #0:11[0x1c97]: Unknown: none ([11][0][0][0] / 0x000B)
    Stream #0:12[0x1bc4]: Unknown: none ([5][0][0][0] / 0x0005)
    Stream #0:13[0x1bc6]: Unknown: none ([5][0][0][0] / 0x0005)
  Program 17540
    Metadata:
      service_name    : BBC ONE HD
      service_provider:
    Stream #0:28[0x19c9]: Video: h264 (High) ([27][0][0][0] / 0x001B), yuv420p(tv, bt709, top first), 1920x1080 [SAR 1:1 DAR 16:9], 25 fps, 25 tbr, 90k tbn, 50 tbc
    Stream #0:14[0x19ca](eng): Audio: aac_latm (LC) ([17][0][0][0] / 0x0011), 48000 Hz, stereo, fltp
    Stream #0:29[0x19ce](eng): Unknown: none ([17][0][0][0] / 0x0011) (visual impaired) (descriptions) (dependent)
    Stream #0:30[0x19cd](eng): Subtitle: dvb_subtitle ([6][0][0][0] / 0x0006)
    Stream #0:5[0x1c86]: Unknown: none ([11][0][0][0] / 0x000B)
    Stream #0:11[0x1c97]: Unknown: none ([11][0][0][0] / 0x000B)
    Stream #0:12[0x1bc4]: Unknown: none ([5][0][0][0] / 0x0005)
    Stream #0:13[0x1bc6]: Unknown: none ([5][0][0][0] / 0x0005)
  Program 17603
    Metadata:
      service_name    : ITV HD
      service_provider:
    Stream #0:18[0xc9]: Video: h264 (High) ([27][0][0][0] / 0x001B), yuv420p(tv, bt709, top first), 1920x1080 [SAR 1:1 DAR 16:9], 25 fps, 25 tbr, 90k tbn, 50 tbc
    Stream #0:31[0xca](eng): Audio: aac_latm (LC) ([17][0][0][0] / 0x0011), 48000 Hz, stereo, fltp
    Stream #0:20[0xce](eng): Audio: aac_latm (HE-AACv2) ([17][0][0][0] / 0x0011), 48000 Hz, stereo, fltp (visual impaired) (descriptions) (dependent)
    Stream #0:32[0xcd](eng): Subtitle: dvb_subtitle ([6][0][0][0] / 0x0006)
  Program 17664
    Metadata:
      service_name    : Channel 4 HD
      service_provider:
    Stream #0:0[0x12d]: Video: h264 (High) ([27][0][0][0] / 0x001B), yuv420p(tv, bt709, top first), 1920x1080 [SAR 1:1 DAR 16:9], 25 fps, 25 tbr, 90k tbn, 50 tbc
    Stream #0:1[0x12e](eng): Audio: aac_latm (LC) ([17][0][0][0] / 0x0011), 48000 Hz, stereo, fltp
    Stream #0:2[0x132](eng): Unknown: none ([17][0][0][0] / 0x0011) (visual impaired) (descriptions) (dependent)
    Stream #0:3[0x131](eng): Subtitle: dvb_subtitle ([6][0][0][0] / 0x0006)
  Program 17728
    Metadata:
      service_name    : Channel 5 HD
      service_provider:
    Stream #0:19[0x1901]: Video: h264 (High) ([27][0][0][0] / 0x001B), yuv420p(tv, bt709, top first), 1920x1080 [SAR 1:1 DAR 16:9], 25 fps, 25 tbr, 90k tbn, 50 tbc
    Stream #0:25[0x1902](eng): Audio: aac_latm (LC) ([17][0][0][0] / 0x0011), 48000 Hz, stereo, fltp
    Stream #0:26[0x1906](eng): Unknown: none ([17][0][0][0] / 0x0011) (visual impaired) (descriptions) (dependent)
    Stream #0:27[0x1905](eng): Subtitle: dvb_subtitle ([6][0][0][0] / 0x0006)
  Program 17920
    Metadata:
      service_name    : BBC THREE HD
      service_provider:
    Stream #0:33[0x1b59]: Video: h264 (High) ([27][0][0][0] / 0x001B), yuv420p(tv, bt709, progressive), 1920x1080 [SAR 1:1 DAR 16:9], 25 fps, 25 tbr, 90k tbn, 50 tbc
    Stream #0:17[0x1b5a](eng): Audio: aac_latm (LC), 48000 Hz, stereo, fltp
    Stream #0:34[0x1b5e](eng): Audio: aac_latm (HE-AACv2) ([17][0][0][0] / 0x0011), 48000 Hz, stereo, fltp (visual impaired) (descriptions) (dependent)
    Stream #0:35[0x1b5d](eng): Subtitle: dvb_subtitle ([6][0][0][0] / 0x0006)
    Stream #0:4[0x1c87]: Unknown: none ([11][0][0][0] / 0x000B)
    Stream #0:5[0x1c86]: Unknown: none ([11][0][0][0] / 0x000B)
    Stream #0:12[0x1bc4]: Unknown: none ([5][0][0][0] / 0x0005)
  Program 18112
    Metadata:
      service_name    : CBBC HD
      service_provider:
    Stream #0:4[0x1c87]: Unknown: none ([11][0][0][0] / 0x000B)
    Stream #0:5[0x1c86]: Unknown: none ([11][0][0][0] / 0x000B)
    Stream #0:6[0x1bc5]: Unknown: none ([5][0][0][0] / 0x0005)
  Program 20160
    Metadata:
      service_name    : TBN UK
      service_provider:
    Stream #0:15[0x1edd]: Video: h264 (High) ([27][0][0][0] / 0x001B), yuv420p(tv, bt470bg, top first), 544x576 [SAR 64:33 DAR 544:297], 25 fps, 25 tbr, 90k tbn, 50 tbc
    Stream #0:16[0x1ede](eng): Audio: aac_latm (LC) ([17][0][0][0] / 0x0011), 48000 Hz, stereo, fltp
  Program 20256
    Metadata:
      service_name    : 5SELECT
      service_provider:
    Stream #0:21[0x1d4d]: Video: h264 ([27][0][0][0] / 0x001B), none, 25 fps, 25 tbr, 90k tbn
    Stream #0:22[0x1d4e](eng): Audio: aac_latm (LC) ([17][0][0][0] / 0x0011), 48000 Hz, stereo, fltp
    Stream #0:23[0x1d52](eng): Unknown: none ([17][0][0][0] / 0x0011) (visual impaired) (descriptions) (dependent)
    Stream #0:24[0x1d51](eng): Subtitle: dvb_subtitle ([6][0][0][0] / 0x0006)

[mvallevand]

dvbv5-zap can capture the full mux with the -P option

Martin

[sub]

Yep no problem - I've put it on my server here: https://www.cae.me.uk/tmp/mux.ts (270MB)

This is the entire mux, so there's a few channels in it (dump at the bottom of post). I think the only problematic ones are BBC1 HD and BBC2 HD, the others seem ok?

Thanks. I've downloaded the file, and set it up in my signal generator and managed to scan in then channels, and can watch them. I'll check the subtitles a little later.