Hello, I'm trying to add subtitles in the conversion to fmp4 as follows;

`mp4-dash.py --hls MP4/video.mp4 [+format=webvtt,+language=por]MP4/por.vtt [+format=webvtt,+language=forced]MP4/forced.vtt
`

But I'm getting this error message and no subtitles are added, any solution?


```
Parsing media file 1: MP4/video.mp4
Splitting media file (audio) MP4/video.mp4
Splitting media file (audio) MP4/video.mp4
Splitting media file (video) MP4/video.mp4
Processing and Copying subtitles file MP4/por.vtt
Processing and Copying subtitles file MP4/forced.vtt
ERROR: local variable 'language_name' referenced before assignment
```
Subtitles with mp4-dash
This is a GitHub Issue
repo:Bento4
owner:axiomatic-systems
Title : Subtitles with mp4-dash
Issue date:

--- start body ---
Hello, I'm trying to add subtitles in the conversion to fmp4 as follows;

`mp4-dash.py --hls MP4/video.mp4 [+format=webvtt,+language=por]MP4/por.vtt [+format=webvtt,+language=forced]MP4/forced.vtt
`

But I'm getting this error message and no subtitles are added, any solution?


```
Parsing media file 1: MP4/video.mp4
Splitting media file (audio) MP4/video.mp4
Splitting media file (audio) MP4/video.mp4
Splitting media file (video) MP4/video.mp4
Processing and Copying subtitles file MP4/por.vtt
Processing and Copying subtitles file MP4/forced.vtt
ERROR: local variable 'language_name' referenced before assignment
```
--- end body ---
