Hi,
We receive several live streams each containing subtitles tracks and we can’t display this subtitles with HLS or DASH players client side.
ffprobe commands on input source streams shows that this subtitles tracks can be encoded using either dvb_teletext or dvb_subtitle.
Example 1 :
Stream #0:0[0x1e1]: Video: h264 (Main) ([27][0][0][0] / 0x001B),
yuv420p(tv, top first), 720x576 [SAR 16:11 DAR 20:11], 25 fps, 25 tbr,
90k tbn, 50 tbc
Stream #0:1[0x1e2](fra): Audio: aac (LC) ([15][0][0][0] / 0x000F), 48000 Hz, stereo, fltp, 64 kb/s
Stream #0:1[0x1e2](eng): Audio: aac (LC) ([15][0][0][0] / 0x000F), 48000 Hz, stereo, fltp, 64 kb/s
Stream #0:4[0x20f](fra): Subtitle: dvb_teletext ([6][0][0][0] / 0x0006)
Example 2 :
Stream #0:0[0x1fe]: Video: h264 (High) ([27][0][0][0] / 0x001B),
yuv420p(tv, bt709, top first), 1920x1080 [SAR 1:1 DAR 16:9], 24.75 fps,
25 tbr, 90k tbn, 50 tbc
Stream #0:1[0x209](fra): Audio: ac3 ([6][0][0][0] / 0x0006), 48000 Hz, stereo, fltp, 192 kb/s
Stream #0:2[0x20a](eng): Audio: ac3 ([6][0][0][0] / 0x0006), 48000 Hz, stereo, fltp, 192 kb/s
Stream #0:3[0x21e](fra): Subtitle: dvb_subtitle ([6][0][0][0] / 0x0006)
This streams are transcoded using ffmpeg command line, keeping the subtitle track unchanged :
ffmpeg -i udp://<InputIP:Port>?fifo_size=5000000&overrun_nonfatal=1 \
-scodec copy
-vcodec <video options> \
-acodec <audio options> \
-f mpegts udp://<WowzaIP:Port>?pkt_size=1316
The output stream plays well for Audio and Video with HLS, DASH and RTMP on our Wowza server.
Following this tutorial :
Our server is well set up to injest DVB Teletext subtitle data for closed captionning as we can see in the log files on one sample channel :
241676 2018-10-08 15:06:15 CEST comment server INFO 200 -
RTPDePacketizerMPEGTSMonitorDVBTeletext.onPMT[/path/to/file.stream.stream]:
programID:1 - - - 1468438.722 - - - - - - - - - - - - -
- - - - - - - - - - - -
241677 2018-10-08 15:06:15
CEST comment server INFO 200 -
RTPDePacketizerMPEGTSMonitorDVBTeletext.onPMT[/path/to/file.stream.stream]:
Hit teletext PID: 0x102 - - - 1468438.722 - - - - - - - - -
- - - - - - - - - - - - - - - -
241678 2018-10-08
15:06:15 CEST comment server INFO 200 -
RTPDePacketizerMPEGTSMonitorDVBTeletext.onPMT[/path/to/file.stream.stream]:
Subtitle page: lang:fra type:5 magazine:8 page_number:88 - - -
1468438.722 - - - - - - - - - - - - - - - - - - - -
- - - - -
241679 2018-10-08 15:06:15 CEST comment server
INFO 200 -
RTPDePacketizerMPEGTSMonitorDVBTeletext.onPMT[/path/to/file.stream.stream]:
Add teletext PID: 0x102 - - - 1468438.722 - - - - - - - - -
- - - - - - - - - - - - - - - -
241777 2018-10-08 15:06:20 CEST comment server INFO 200 -
RTPDePacketizerMPEGTSMonitorDVBTeletext.onPMT[/path/to/file.stream.stream]:
programID:1 - - - 1468443.009 - - - - - - - - - - - - -
- - - - - - - - - - - -
241778 2018-10-08 15:06:20
CEST comment server INFO 200 -
RTPDePacketizerMPEGTSMonitorDVBTeletext.onPMT[/path/to/file.stream.stream]:
Hit teletext PID: 0x102 - - - 1468443.009 - - - - - - - - -
- - - - - - - - - - - - - - - -
241779 2018-10-08
15:06:20 CEST comment server INFO 200 -
RTPDePacketizerMPEGTSMonitorDVBTeletext.onPMT[/path/to/file.stream.stream]:
Subtitle page: lang:fra type:5 magazine:8 page_number:88 - - -
1468443.009 - - - - - - - - - - - - - - - - - - - -
- - - - -
241780 2018-10-08 15:06:20 CEST comment server
INFO 200 -
RTPDePacketizerMPEGTSMonitorDVBTeletext.onPMT[/path/to/file.stream.stream]:
Add teletext PID: 0x102 - - - 1468443.01 - - - - - - - - -
- - - - - - - - - - - - - - - -
We also enabled Closed Captions and especially AMF onTextData on our live application following this tutorial :
https://www.wowza.com/docs/How-to-configure-closed-captioning-for-live-streaming#ontextdata
After restarting the server, no substitles seem to be enabled for HLS Streams :
playlist.m3u8 :
#EXTM3U
#EXT-X-VERSION:3
#EXT-X-STREAM-INF:BANDWIDTH=15609181,CODECS="avc1.100.40,mp4a.40.2",RESOLUTION=1920x1080
chunklist_w1063099262.m3u8?ticket=chuck
chunklist_w1063099262.m3u8 :
#EXTM3U
#EXT-X-VERSION:3
#EXT-X-TARGETDURATION:11
#EXT-X-MEDIA-SEQUENCE:36
#EXTINF:10.2,
media_w1063099262_36.ts?ticket=chuck
#EXTINF:10.48,
media_w1063099262_37.ts?ticket=chuck
#EXTINF:9.4,
media_w1063099262_38.ts?ticket=chuck
ffprobe -i media_w1063099262_36.ts :
Stream #0:0[0x102]: Data: timed_id3 (ID3 / 0x20334449)
Stream
#0:1[0x100]: Video: h264 (High) ([27][0][0][0] / 0x001B), yuv420p(tv,
bt709), 1920x1080 [SAR 1:1 DAR 16:9], 25 fps, 25 tbr, 90k tbn, 50 tbc
Stream #0:2[0x101]: Audio: aac (LC) ([15][0][0][0] / 0x000F), 44100 Hz, stereo, fltp, 135 kb/s
Same for DASH Streams, only video and audio tracks are listed :
<?xml version="1.0" encoding="UTF-8"?>
<MPD xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="urn:mpeg:dash:schema:mpd:2011"
xmlns:xlink="http://www.w3.org/1999/xlink"
xsi:schemaLocation="urn:mpeg:DASH:schema:MPD:2011
http://standards.iso.org/ittf/PubliclyAvailableStandards/MPEG-DASH_schema_files/DASH-MPD.xsd"
profiles="urn:mpeg:dash:profile:isoff-live:2011"
type="dynamic"
minimumUpdatePeriod="PT10.055S"
publishTime="2018-10-08T14:57:08Z"
availabilityStartTime="2018-10-08T14:47:56Z"
timeShiftBufferDepth="PT49.96S"
suggestedPresentationDelay="PT15.0S"
minBufferTime="PT6.0S">
<ProgramInformation>
<Title>channel/3005/web_1080p.stream</Title>
</ProgramInformation>
<Location>http://<server>/<application>/manifest_mvtime_w1712721404_qdGlja2V0PWNodWNr.mpd</Location>
<Period id="0" start="PT0.0S">
<AdaptationSet id="0" group="1" mimeType="video/mp4" width="1920"
height="1080" par="16:9" frameRate="25" segmentAlignment="true"
startWithSAP="1" subsegmentAlignment="true"
subsegmentStartsWithSAP="1">
<SegmentTemplate
timescale="90000"
media="chunk_ctvideo_cfm4s_rid$RepresentationID$_cs$Time$_w1712721404_qdGlja2V0PWNodWNr_mpd.m4s"
initialization="chunk_ctvideo_cfm4s_rid$RepresentationID$_cinit_w1712721404_qdGlja2V0PWNodWNr_mpd.m4s">
<SegmentTimeline>
<S t="45039600" d="950400"/>
<S d="806400"/>
<S d="939600"/>
<S d="910800"/>
<S d="889200"/>
</SegmentTimeline>
</SegmentTemplate>
<Representation id="p0va0br15100423" codecs="avc1.640028" sar="1:1" bandwidth="15100423" />
</AdaptationSet>
<AdaptationSet id="1" group="2" mimeType="audio/mp4" lang="eng"
segmentAlignment="true" startWithSAP="1" subsegmentAlignment="true"
subsegmentStartsWithSAP="1">
<AudioChannelConfiguration schemeIdUri="urn:mpeg:dash:23003:3:audio_channel_configuration:2011" value="2"/>
<SegmentTemplate timescale="44100"
media="chunk_ctaudio_cfm4s_rid$RepresentationID$_cs$Time$_w1712721404_qdGlja2V0PWNodWNr_mpd.m4s"
initialization="chunk_ctaudio_cfm4s_rid$RepresentationID$_cinit_w1712721404_qdGlja2V0PWNodWNr_mpd.m4s">
<SegmentTimeline>
<S t="22070110" d="465916"/>
<S d="395268"/>
<S d="459743"/>
<S d="446468"/>
<S d="435223"/>
</SegmentTimeline>
</SegmentTemplate>
<Representation id="p0aa0br141831" codecs="mp4a.40.2" audioSamplingRate="44100" bandwidth="141831">
</Representation>
</AdaptationSet>
</Period>
</MPD>
Do we need to enable CEA-608 caption as well as AMF onTextData to have the subtitles visible on both HLS and DASH ?
Best Regards,
