# Rules for extracting captions from sources
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To use captions in a source, Elemental Live must be able to extract the captions. The rules are as follows:
+ Elemental Live can always extract sidecar captions from the source, so long as Elemental Live supports the captions format.
+ Elemental Live can always support captions from a streaming source, so long as Elemental Live supports the captions format and the input type.
+ Elemental Live can't necessarily extract captions from a file source. Even if Elemental Live supports the captions format, it can extract the captions only from specific container types. See the table that follows.


| Container in file input | Elemental Live can extract captions from the container? | 
| --- | --- | 
| Adobe Flash |   | 
| Audio Video Interleave (AVI) |   | 
| HLS | Yes | 
| Matroska |   | 
| MP4 | Yes | 
| MPEG Transport Stream (TS) | Yes | 
| MPEG-1 System Stream |   | 
| MXF | Yes | 
| No container | Yes | 
| QuickTime | Yes | 
| WAV | Yes  |