Hi,

I am encountering frequent crashes while playing back tiled VR content using the compositor, you can find the way to reproduce it below.

Encoder command:

```
 gpac\
 -i test_30fps.mp4:FID=I reframer:rt=on:SID=I:FID=REGULATED\
 ffsws:SID=REGULATED:FID=Y:osize=1024x512:ofmt=yuv420\
 -+kvazaar-params=preset=ultrafast,tiles=4x4,slices=tiles,mv-constraint=frametilemargin,input-format=P420,qp=16,rc-algorithm=lambda\
 ffenc:SID=Y:FID=K1:c=libkvazaar:b=10M:size=$SIZE:fintra=4:rc\
 tilesplit:SID=K1:FID=1 -o http://localhost:8080/live.mpd:gpac:dmode\=dynamic:segdur\=4:cdur\=2:asto\=2:llhls\=off:profile\=live:rdirs\=outdir:template\=seg_live_:SID\=1  -stats  -logs=all@info -log-file=file_to_tiles_server.log
```

Player command

``` 
gpac compositor:src=http://localhost:8080/live.mpd#VR vout:buffer=8000 -graph -logs=all@info -log-file=compositor_crash.log 
```

[Link containing](https://www.mediafire.com/file/991b9w4ilkyo9ac/compositor_crash1.zip/file):

- player log
- encoder log
- screenshot of the stacktrace
The video file used https://github.com/gpac/gpac/issues/1849

OS: ubuntu 21.04 
GPAC: version 1.1.0-DEV-rev1283-gc51f07f11-master
Compiled in debug
Ran using` _NV_PRIME_RENDER_OFFLOAD=1 __GLX_VENDOR_LIBRARY_NAME=nvidia` to make use of the nvidia GPU 

-------
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/2013/07/16/how-to-file-a-bug-properly/

Playing with back tiled video in VR with compositor crashes
This is a GitHub Issue
repo:gpac
owner:gpac
Title : Playing with back tiled video in VR with compositor crashes
Issue date:

--- start body ---
Hi,

I am encountering frequent crashes while playing back tiled VR content using the compositor, you can find the way to reproduce it below.

Encoder command:

```
 gpac\
 -i test_30fps.mp4:FID=I reframer:rt=on:SID=I:FID=REGULATED\
 ffsws:SID=REGULATED:FID=Y:osize=1024x512:ofmt=yuv420\
 -+kvazaar-params=preset=ultrafast,tiles=4x4,slices=tiles,mv-constraint=frametilemargin,input-format=P420,qp=16,rc-algorithm=lambda\
 ffenc:SID=Y:FID=K1:c=libkvazaar:b=10M:size=$SIZE:fintra=4:rc\
 tilesplit:SID=K1:FID=1 -o http://localhost:8080/live.mpd:gpac:dmode\=dynamic:segdur\=4:cdur\=2:asto\=2:llhls\=off:profile\=live:rdirs\=outdir:template\=seg_live_:SID\=1  -stats  -logs=all@info -log-file=file_to_tiles_server.log
```

Player command

``` 
gpac compositor:src=http://localhost:8080/live.mpd#VR vout:buffer=8000 -graph -logs=all@info -log-file=compositor_crash.log 
```

[Link containing](https://www.mediafire.com/file/991b9w4ilkyo9ac/compositor_crash1.zip/file):

- player log
- encoder log
- screenshot of the stacktrace
The video file used https://github.com/gpac/gpac/issues/1849

OS: ubuntu 21.04 
GPAC: version 1.1.0-DEV-rev1283-gc51f07f11-master
Compiled in debug
Ran using` _NV_PRIME_RENDER_OFFLOAD=1 __GLX_VENDOR_LIBRARY_NAME=nvidia` to make use of the nvidia GPU 

-------
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/2013/07/16/how-to-file-a-bug-properly/

--- end body ---

The issue describes a crash in the GPAC compositor when playing back tiled VR content, which may indicate a potential vulnerability related to memory management or resource handling in the compositor. However, without specific details on the nature of the crash or exploitability, it is difficult to classify this as a security vulnerability. It appears to be a bug rather than a security issue.