Bug Description
1. Summary
We are noticing a player crash related to VTT subtitles when a subtitle containing the < character is displayed. The issue occurs when using Shaka subtitles. We do not encounter the problem with the native player’s subtitle engine.
Bug Severity
- Impacts operation of app
- Blocks current development
- Improvement suggestion
- Issue with documentation (If selected, please share the doc link and describe the issue)
- Other
2. Steps to Reproduce
- Load video with subtitle tracks containing the “<” char. For example:
12 00:02:53.240 --> 00:02:55.280 - <Buon Natale. - Grazie, dottoressa. - Turn on subtitles
- Go to the moment when the caption containing the “<” character is displayed.
3. Observed Behavior
The application crashes when it tries to render a caption containing the “<” character.
4. Expected Behavior
The application correctly displays the caption without any crashes.
4.a Possible Root Cause & Temporary Workaround
The crash occurs in the TimeMarchesOnAlgo class of @amzn/react-native-w3cmedia, when executing the renderActiveCues method. It appears that the rendering engine interprets the “<” character as the opening of an HTML tag that is not closed.
We tried using the native player subtitles as an alternative, but as reported in this task, it does not support switching between multiple subtitle tracks.
5. Logs or crash report
Crash report:
11817#crash_1765905331_5000_5000_25753_145689511_Toolkit-UI.acr (657,6 KB)
6. Environment
Please fill out the fields related to your bug below:
-
SDK Version: 0.20.3067
-
App State:
Foreground -
OS Information
NAME="OS" OE_VERSION="4.0.0" OS_MAJOR_VERSION="1" OS_MINOR_VERSION="1" RELEASE_ID="10" OS_VERSION="1.1" BRANCH_CODE="TV Ship" BUILD_DESC="OS 1.1 (TV Ship/4446)" BUILD_FINGERPRINT="4.0.184842.0(3072cab629675a74)/4446N:user-external/release-keys" BUILD_VARIANT="user-external" BUILD_TAGS="release-keys" BUILD_DATE="Sun Nov 16 06:26:48 UTC 2025" BUILD_TIMESTAMP="1763274408" VERSION_NUMBER="1001010444650"
7. Example Code Snippet / Screenshots / Screengrabs
Include any relevant code or component setup in React Native that can help reproduce the bug.
import { ExampleComponent } from 'custom-sdk';
<ExampleComponent config={{ key: 'value' }} />
Playback Issues
Please share the following details in addition:_
- Player SDK:
Shaka - Player SDK Version:
4.6.18, 4.8.5 - Video Codecs:
h.264 - Manifest Types:
dash - Subtitles Format:
text/vtt - @amzn/react-native-w3cmedia:
2.1.80, 2.1.87
Q: If applicable, please provide your media/content url
If this is created dynamically, tokenized, etc please provide a way for us to access it
[N/A or Content / Media Url for testing]
Q: Are there any special headers required to reproduce the issue you are facing?
[N/A or Insert Headers]
Additionally please provide the following if possible
Provide Screenshots / Screengrabs / Logs. Please include as much information as you can that will help debug.
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Additional Context
Any Additional Context you would like to provide?
Add any other relevant information, such as recent updates to the SDK, dependencies, or device OS that may affect the bug.
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