Closed Captioning with multiple bitrates (smil) not working

Wowza Streaming Engine
1

Hi,

I’d like to use the speechToText module as described here: Convert speech to text to generate live stream captions with Azure AI Speech Services | Wowza Docs & APIs

So far it works fine for single streams, but I’d like to transcode in multiple bitrates.
I have the transcoder set to transcode the stream “wowzatest” into wowzatest_720p and wowzatest_360p streams.

When I access the HLS streams via “/wowzatest_720p/playlist.m3u8” everything works fine and I see the subtitles.

But I need bitrate switching, so I created this SMIL, according to the documentation: Convert speech to text to generate live stream captions with Azure AI Speech Services | Wowza Docs & APIs

<?xml version="1.0" encoding="UTF-8"?>
<smil title="">
  <body>
    <switch>
      <video height="720" src="wowzatest_720p" width="1280">
        <param name="videoBitrate" value="3500000" valuetype="data"></param>
        <param name="audioBitrate" value="128000" valuetype="data"></param>
        <param name="cupertinoTag.SUBTITLES" value="subs" valuetype="data"/>
      </video>
      <video height="360" src="wowzatest_360p" width="640">
        <param name="videoBitrate" value="1300000" valuetype="data"></param>
        <param name="audioBitrate" value="128000" valuetype="data"></param>
        <param name="cupertinoTag.SUBTITLES" value="subs" valuetype="data"/>
      </video>
      <textstream src="wowzatest_720p" system-language="ger">
        <param name="iswowzacaptionstream" value="true" valuetype="data"/>
        <param name="cupertinoTag.TYPE" value="SUBTITLES" valuetype="data"/>
        <param name="cupertinoTag.GROUP-ID" value="subs" valuetype="data"/>
        <param name="cupertinoTag.DEFAULT" value="YES" valuetype="data"/>
        <param name="cupertinoTag.FORCED" value="NO" valuetype="data"/>
      </textstream>
    </switch>
  </body>
</smil>

Unfortunately, when accessing the stream with “/smil:wowzatestmbr.smil/playlist.m3u8”, both streams don’t show subtitles (no CC icon).

Interestingly, the wowzatestmbr.smil/playlist.m3u8 contains this information: (doesn’t work)

#EXTM3U
#EXT-X-VERSION:3
#EXT-X-MEDIA:TYPE=CLOSED-CAPTIONS,GROUP-ID="subs",NAME="Deutsch",FORCED=NO,AUTOSELECT=YES,DEFAULT=YES,LANGUAGE="ger"
#EXT-X-STREAM-INF:BANDWIDTH=3628000,RESOLUTION=1280x720,CLOSED-CAPTIONS="cc"
chunklist_w857691546_b3628000.m3u8
#EXT-X-STREAM-INF:BANDWIDTH=1428000,RESOLUTION=640x360,CLOSED-CAPTIONS="cc"
chunklist_w857691546_b1428000.m3u8

Whereas when accessing the wowzatest_720p/playlist.m3u8 directly, it shows this: (works)

#EXTM3U
#EXT-X-VERSION:3
#EXT-X-MEDIA:TYPE=SUBTITLES,GROUP-ID="subs",NAME="Deutsch",FORCED=NO,AUTOSELECT=YES,URI="subtitlelist_lde_w663707475.m3u8",LANGUAGE="de"
#EXT-X-STREAM-INF:BANDWIDTH=2448140,CODECS="avc1.4d401f,mp4a.40.2",RESOLUTION=1280x720,SUBTITLES="subs"
chunklist_w663707475.m3u8

Any ideas?

2

Hi, if it’s of interest: I have a module that does this - PM me or email info@ztream.io

3

So it’s not possible with standard WSE? That’d be strange…
I sent you a mail :slight_smile:

1 Like
4

Hello @Bernhard_Schmidt

Thanks for reaching out!

We’ve already addressed your query regarding “Closed Captioning with multiple bitrates (smil) not working” in the support ticket you submitted - 36112165271.

Please refer to the detailed response provided in the ticket for the solution. If you have any further questions after reviewing it, please feel free to open a new support ticket, and we’ll be happy to assist you further.

Regards,
Vihari

5

Hey Vihari! Can you share the answer so rest of community can benefit?

6

@Vihari_Kumar Can you follow-up. Does this work if it is configured properly? If so, what is the trick?

Or does this not currently work in WSE?

7

.. doesn’t want to share his “secret” knowledge .. :slight_smile:

8

Hello @Scott_Kellicker2

We apologize for the delay in the response as we were working with Bernhard on troubleshooting the issue. We found that a property named “cupertinoLiveCaptionsUseWebVTT” was not enabled in the Application.xml which was causing the captions to not be viewed on playback. As mentioned in the article, the renditions include WebVTT captions.

Bernard confirmed that enabling the property resolved the issue and the workflow is working as expected.

We will be updating the article to mention the property “cupertinoLiveCaptionsUseWebVTT” needs to be enabled.

Best Regards,
Drumil Desai​

Technical Support Engineer

Wowza | The solution you start with, the partner you scale with.

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