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/
- [x] 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/bug-reporting/

I'm currently trying to work in a multitrack playlist hls packager, but gpac is not aplying the group correctly to each track 

```bash
gpac \
      -i udp://0.0.0.0:5010/:gpac:listen=true:tsprobe=true:#HLSGroup=LL_V_Group:#Representation=LL_V_Track:#HLSMExt=DEFAULT=YES reframer:rt=on \
      -i udp://0.0.0.0:5011/:gpac:listen=true:tsprobe=true:#HLSGroup=Aug1_V_Group:#Representation=Aug1_V_Track:#HLSMExt=DEFAULT=NO reframer:rt=on \
      -i udp://0.0.0.0:5012/:gpac:listen=true:tsprobe=true:#HLSGroup=Aug2_V_Group:#Representation=Aug2_V_Track:#HLSMExt=DEFAULT=NO reframer:rt=on \
      -i udp://0.0.0.0:6010/:gpac:listen=true:tsprobe=true:#HLSGroup=LL_A_Group:#Representation=LL_A_Track reframer:rt=on \
      -i udp://0.0.0.0:6011/:gpac:listen=true:tsprobe=true:#HLSGroup=Aug1_A_Group:#Representation=Aug1_A_Track reframer:rt=on \
      -i udp://0.0.0.0:6012/:gpac:listen=true:tsprobe=true:#HLSGroup=Aug2_A_Group:#Representation=Aug2_A_Track reframer:rt=on \
      -o http://origin:8081/live/upload/playlist.m3u8:gpac:buf=-150:ll_part_hb=-1:ll_rend_rep=true:hls_ap=true:seg_sync=no:segdur=6.0:cdur=0.5:llhls=sf:hlsc=true:cmaf=cmf2:dmode=dynamic:pssh=v:hmode=push
```

The generated playlist looks something like this...

```
#EXTM3U
#EXT-X-VERSION:6
#EXT-X-INDEPENDENT-SEGMENTS

#EXT-X-MEDIA:TYPE=VIDEO,GROUP-ID="Aug1_V_Group",DEFAULT=NO,NAME="Aug1_V_Track",URI="playlist_1.m3u8"
#EXT-X-MEDIA:TYPE=VIDEO,GROUP-ID="Aug2_V_Group",DEFAULT=NO,NAME="Aug2_V_Track",URI="playlist_2.m3u8"
#EXT-X-MEDIA:TYPE=VIDEO,GROUP-ID="LL_V_Group",DEFAULT=YES,NAME="LL_V_Track",URI="playlist_3.m3u8"
#EXT-X-STREAM-INF:BANDWIDTH=1024443,CODECS="mp4a.40.2,avc1.4D401F",RESOLUTION=1280x720,VIDEO="Aug1_V_Group"
playlist_4.m3u8

#EXT-X-STREAM-INF:BANDWIDTH=1024430,CODECS="mp4a.40.2,avc1.4D401F",RESOLUTION=1280x720,VIDEO="Aug1_V_Group"
playlist_5.m3u8

#EXT-X-STREAM-INF:BANDWIDTH=1024443,CODECS="mp4a.40.2,avc1.4D401F",RESOLUTION=1280x720,VIDEO="Aug1_V_Group"
playlist_6.m3u8

```

Is possible to see that the generated EXT-X-STREAM-INF is not pointing to the seted VIDEO with the HLSGroup, this happens also when the primary is the VIDEO (hls_ap=false) the AUDIO attribute in the EXT-X-STREAM-INF is pointing to the same audio and not the one setted in the HLSGroup

am I using GPAC wrong? could this be a bug?

Thanks in advance
HLSGroup not being applied correctly
This is a GitHub Issue
repo:gpac
owner:gpac
Title : HLSGroup not being applied correctly
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/
- [x] 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/bug-reporting/

I'm currently trying to work in a multitrack playlist hls packager, but gpac is not aplying the group correctly to each track 

```bash
gpac \
      -i udp://0.0.0.0:5010/:gpac:listen=true:tsprobe=true:#HLSGroup=LL_V_Group:#Representation=LL_V_Track:#HLSMExt=DEFAULT=YES reframer:rt=on \
      -i udp://0.0.0.0:5011/:gpac:listen=true:tsprobe=true:#HLSGroup=Aug1_V_Group:#Representation=Aug1_V_Track:#HLSMExt=DEFAULT=NO reframer:rt=on \
      -i udp://0.0.0.0:5012/:gpac:listen=true:tsprobe=true:#HLSGroup=Aug2_V_Group:#Representation=Aug2_V_Track:#HLSMExt=DEFAULT=NO reframer:rt=on \
      -i udp://0.0.0.0:6010/:gpac:listen=true:tsprobe=true:#HLSGroup=LL_A_Group:#Representation=LL_A_Track reframer:rt=on \
      -i udp://0.0.0.0:6011/:gpac:listen=true:tsprobe=true:#HLSGroup=Aug1_A_Group:#Representation=Aug1_A_Track reframer:rt=on \
      -i udp://0.0.0.0:6012/:gpac:listen=true:tsprobe=true:#HLSGroup=Aug2_A_Group:#Representation=Aug2_A_Track reframer:rt=on \
      -o http://origin:8081/live/upload/playlist.m3u8:gpac:buf=-150:ll_part_hb=-1:ll_rend_rep=true:hls_ap=true:seg_sync=no:segdur=6.0:cdur=0.5:llhls=sf:hlsc=true:cmaf=cmf2:dmode=dynamic:pssh=v:hmode=push
```

The generated playlist looks something like this...

```
#EXTM3U
#EXT-X-VERSION:6
#EXT-X-INDEPENDENT-SEGMENTS

#EXT-X-MEDIA:TYPE=VIDEO,GROUP-ID="Aug1_V_Group",DEFAULT=NO,NAME="Aug1_V_Track",URI="playlist_1.m3u8"
#EXT-X-MEDIA:TYPE=VIDEO,GROUP-ID="Aug2_V_Group",DEFAULT=NO,NAME="Aug2_V_Track",URI="playlist_2.m3u8"
#EXT-X-MEDIA:TYPE=VIDEO,GROUP-ID="LL_V_Group",DEFAULT=YES,NAME="LL_V_Track",URI="playlist_3.m3u8"
#EXT-X-STREAM-INF:BANDWIDTH=1024443,CODECS="mp4a.40.2,avc1.4D401F",RESOLUTION=1280x720,VIDEO="Aug1_V_Group"
playlist_4.m3u8

#EXT-X-STREAM-INF:BANDWIDTH=1024430,CODECS="mp4a.40.2,avc1.4D401F",RESOLUTION=1280x720,VIDEO="Aug1_V_Group"
playlist_5.m3u8

#EXT-X-STREAM-INF:BANDWIDTH=1024443,CODECS="mp4a.40.2,avc1.4D401F",RESOLUTION=1280x720,VIDEO="Aug1_V_Group"
playlist_6.m3u8

```

Is possible to see that the generated EXT-X-STREAM-INF is not pointing to the seted VIDEO with the HLSGroup, this happens also when the primary is the VIDEO (hls_ap=false) the AUDIO attribute in the EXT-X-STREAM-INF is pointing to the same audio and not the one setted in the HLSGroup

am I using GPAC wrong? could this be a bug?

Thanks in advance
--- end body ---
