# Adaptive Bitrate SMIL file syntax

**URL:** <https://community.wowza.com/t/adaptive-bitrate-smil-file-syntax/92763>\
**Category:** Wowza Streaming Engine\
**Tags:** closed-captioning\
**Created:** [January 28, 2021, 4:17pm UTC](https://community.wowza.com/t/adaptive-bitrate-smil-file-syntax/92763 "2021-01-28T16:17:00Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![Dan\_LaSusa](https://avatars.discourse-cdn.com/v4/letter/d/f475e1/32.png) [@Dan\_LaSusa](https://community.wowza.com/u/Dan_LaSusa)\
**Post date:** [January 28, 2021, 4:17pm UTC](https://community.wowza.com/t/adaptive-bitrate-smil-file-syntax/92763/1 "2021-01-28T16:17:00Z")

</div>

Hi!

We’re using an SMIL file to deliver ABR streaming to both an MPEG-DASH and HLS stream to jwplayer.

```
sources: [
{file: "https://wowza_server/_definst_/smil:sample.smil/manifest.mpd"},
{file: "https://wowza_server/_definst_/smil:sample.smil/playlist.m3u8"}]

```

As part of the SMIL we’re including the captions

```
<smil>
<head>
</head>
<body>
  <switch>
    <video src="sample-high.mp4" system-bitrate="3000000"/>
    <video src="sample-medium.mp4" system-bitrate="1500000"/>
    <video src="sample-low.mp4" system-bitrate="500000"/>
    <textstream src="sample.srt" systemLanguage="eng" >
      <param name="isWowzaCaptionStream" value="true" />
    </textstream>
  </switch>
</body>
</smil>

```

The video works with both streams, but the captions only work properly with the MPEG-DASH stream. In the HLS stream, the captions are set to the lower left corner (instead of centered) and the CC selector shows “Off” or “Unknown CC” instead of “English”

I found this page on Wowza’s website: [Understanding SMIL file syntax | Wowza Docs & APIs](https://www.wowza.com/docs/understanding-smil-file-syntax)

But there wasn’t any reference for `textstream` options/parameters.

Are there any resources available that talk about `textstream` or how we can configure the SMIL to support some additional options for captions in the HLS stream?

**Things we’ve tried:**

We’ve tried using parameters such as “label”, “Title”, “srcLang” with values set to both “eng” or “English” but none of that has worked.

We’ve also tried those options in the `textstream` directly and also set as a `param`

Thank you for any assistance, or points in the right direction!

Dan

---

<div class="post-metadata">

**Author:** ![Rose\_Power-Wowza\_Com](https://sea2.discourse-cdn.com/flex002/user_avatar/community.wowza.com/rose_power-wowza_com/32/431_2.png) [@Rose\_Power-Wowza\_Com](https://community.wowza.com/u/Rose_Power-Wowza_Com)\
**Post date:** [January 28, 2021, 7:38pm UTC](https://community.wowza.com/t/adaptive-bitrate-smil-file-syntax/92763/2 "2021-01-28T19:38:59Z")

</div>

We do have a docs article that covers the **textstream** parameter in a smil file with some examples. I hope this helps.

[https://www.wowza.com/docs/how-to-stream-webvtt-subtitles-to-ios-for-closed-captioning](https://www.wowza.com/docs/how-to-stream-webvtt-subtitles-to-ios-for-closed-captioning)