Article: How to stream WebVTT subtitles to iOS for closed captioning

Wowza Streaming Engine
1

You can view the page at How to stream WebVTT subtitles to iOS for closed captioning

2

I think the point that videodoctor and I are trying to make is that we don’t want to have to duplicate the same caption files for every bitrate that lives in other folders, we think the specifying the full path in the textstream src would make more sense. E.g.

Currently captions_for_vod_1 has to be replicated into every folder that the vod1 asset lives in. Is my understanding correct, and if so is there a way around it?

Thanks for your help.

3

thanks Richard.

Just to confirm:-

http://localhost:1935/vod/smil:sample.smil/manifest.f4m?wowzacaptionfile=commonFile.ttml —> works

but

http://localhost:1935/vod/smil:sample.smil/manifest.f4m?wowzacaptionfile=/captionsdir/commonFile.ttml -->doesn’t appear to (nor setting it in smil file)

We now have 14 different bit rates in 14 folders - so an option that works would be most appreciated!

4

With ABR VOD SMIL files, why does the captions file need to have the same name as the VOD file when there’s a src attribute for that specifies a full file name? I use a dynamic SMIL creation script for assets, and the current convention seems odd to me. Right now, the Wowza log output seems to look for the caption file on any stream switch, and it’s looking for an exact match to the currently playing file. So, I’d need to make a duplicate caption file for each resolution in the SMIL file, according to my testing.

5

Hi,

We’ll need to look into this closely and post here when we have an update.

Daren

6

The caption file needs to be in the same folder as the video asset.

To use a .smil for ABR you need to be using Wowza 3.6.2 version 6596 or later.

Create a .smil file “vod.smil” for example, the caption info must be added to the smil file using a textstream tag.

And the playback URL would look like this:

http://[wowza-ip-address]:1935/vod/smil:vod.smil/playlist.m3u8

See this section of the article for more details:

VOD ABR playback

Salvadore

7

Hi,

I’ve implemented my system to support onTextData and CEA-608 captioning via server-side-api.

I need to implement the last one WebVTT captioning via server-side-api but I cant find any guides and documentations.

please give me some hint.

thank you.

8

Hi,

I am trying to figure out a solution that allows me to transcribe subtitles live on the fly to go along with a live stream, using WebVTT and iOS. Anyone know of a way to accomplish this?

Thank you,

Alex

9

Hi,

You can use ?wowzacaptionfile=commonFile.ttml in the playback URL, like this:

http://localhost:1935/vod/smil:sample.smil/manifest.f4m?wowzacaptionfile=commonFile.ttml

Richard

10

Okay, I think I see what you are asking now. Let me see what works.

Richard

11

I have been testing and we’ve discussed internally, and it doesn’t work as you are expecting (with content in a sub-folder of content root folder and .ttml file in another sub-folder or content root), but it should. There is not a way to point to the content root. I will open a ticket for you on this, and internal ticket for work.

Thanks for the report,

Richard

12

Huw,

Yes, this has been fixed in development, and should be included in the next patch. I don’t have an exact time frame but I think it will be in the upcoming patch.

Richard

13

Hi,

We’ll need to look into this closely and post here when we have an update.

Daren

I would be interested in the outcome of this as well, as I am having difficulties using captions with smil files. They fine when used directly (i.e. no smil file), but when trying to combine then with bitrates in smil files they don’t work. My scenario is slightly different in that the files have the same names but different but in separate folders.

Many Thanks

Huw

14

Hi Richard,

Has there been any progress on this ticket?

Many Thanks

Huw

15

Huw,

Please email support@wowza.com and we can provide you a patch for this issue.

Scott

16

Hi,

I’ve implemented my system to support onTextData and CEA-608 captioning via server-side-api.

I need to implement the last one WebVTT captioning via server-side-api but I cant find any guides and documentations.

please give me some hint.

thank you.

Hello, cykarma.

There are really no guides for implementing this. We expected that the Wowza team would add additional caption types but not that user’s would.

Can you open a ticket at support@wowza.com and reference this forum post. I’d like to understand what you’ve done/tried so far. I’m both curious as to your use case as well as how you’ve implemented your plug-in and where you are stuck.

Scott