Thanks for reporting your issue. Please make sure these boxes are checked before submitting your issue - thank you!

- [X] I looked for a similar issue and couldn't find any.
- [X] I tried with the latest version of GPAC. Installers available at http://gpac.io/downloads/gpac-nightly-builds/
- [ ] I give enough information for contributors to reproduce my issue (meaningful title, github labels, platform and compiler, command-line ...). I can share files anonymously with this dropbox: https://www.mediafire.com/filedrop/filedrop_hosted.php?drop=eec9e058a9486fe4e99c33021481d9e1826ca9dbc242a6cfaab0fe95da5e5d95

Detailed guidelines: http://gpac.io/2013/07/16/how-to-file-a-bug-properly/

I have a need to download one MP4 file and generate fragment MP4 file on the fly. I followed the example https://github.com/gpac/gpac/wiki/HAS-advanced#quick-record-examples, but got this failure. Can someone please help?
```
 % gpac -i http://localhost:8000/gear4.mp4 -o grab/record.mp4:frag
Unknown argument ":frag" set but not used by any filter - possible matches
- range in filters httpin fin
- store (inter|flat|fstart|tight|frag|sfrag) in filters mp4mx
```


Quick record example fail: Unknown argument ":frag" set but not used by any filter
This is a GitHub Issue
repo:gpac
owner:gpac
Title : Quick record example fail: Unknown argument ":frag" set but not used by any filter
Issue date:

--- start body ---
Thanks for reporting your issue. Please make sure these boxes are checked before submitting your issue - thank you!

- [X] I looked for a similar issue and couldn't find any.
- [X] I tried with the latest version of GPAC. Installers available at http://gpac.io/downloads/gpac-nightly-builds/
- [ ] I give enough information for contributors to reproduce my issue (meaningful title, github labels, platform and compiler, command-line ...). I can share files anonymously with this dropbox: https://www.mediafire.com/filedrop/filedrop_hosted.php?drop=eec9e058a9486fe4e99c33021481d9e1826ca9dbc242a6cfaab0fe95da5e5d95

Detailed guidelines: http://gpac.io/2013/07/16/how-to-file-a-bug-properly/

I have a need to download one MP4 file and generate fragment MP4 file on the fly. I followed the example https://github.com/gpac/gpac/wiki/HAS-advanced#quick-record-examples, but got this failure. Can someone please help?
```
 % gpac -i http://localhost:8000/gear4.mp4 -o grab/record.mp4:frag
Unknown argument ":frag" set but not used by any filter - possible matches
- range in filters httpin fin
- store (inter|flat|fstart|tight|frag|sfrag) in filters mp4mx
```


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