## Description
There is a segment fault detected by AddressSanitizer

## System info
```
Ubuntu 20.04.2 LTS
clang version 12.0.0-++20210402082642+04ba60cfe598-1~exp1~20210402063359.71
MP4Box - GPAC version 1.1.0-DEV-rev1705-gc3ed3094a-master
```

## Build command
```
./configure --static-mp4box --prefix=`realpath ./install` --enable-sanitizer --cc=clang --cxx=clang++
```

## crash command
```
MP4Box -dxml -out /dev/null poc_file
```

## Pocs
[poc.zip](https://github.com/gpac/gpac/files/8000905/poc.zip)


## Crash output
```
==16957==ERROR: AddressSanitizer: SEGV on unknown address 0x62d000142554 (pc 0x00000093684b bp 0x7fff830b8310 sp 0x7fff830b8180 T0)
==16957==The signal is caused by a READ memory access.
    #0 0x93684b in avc_parse_slice /programs/mp4box/builds/build8/src/media_tools/av_parsers.c:5730:7
    #1 0x93684b in gf_avc_parse_nalu /programs/mp4box/builds/build8/src/media_tools/av_parsers.c:6142:9
    #2 0xcda24e in gf_inspect_dump_nalu_internal /programs/mp4box/builds/build8/src/filters/inspect.c:1068:9
    #3 0xcd8b3f in gf_inspect_dump_nalu /programs/mp4box/builds/build8/src/filters/inspect.c:1222:2
    #4 0x4f4863 in dump_isom_nal_ex /programs/mp4box/builds/build8/applications/mp4box/filedump.c:1288:5
    #5 0x4f8170 in dump_isom_xml /programs/mp4box/builds/build8/applications/mp4box/filedump.c:2001:9
    #6 0x4e0da8 in mp4boxMain /programs/mp4box/builds/build8/applications/mp4box/main.c:6171:7
    #7 0x7f99dcef20b2 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x270b2)
    #8 0x41ea6d in _start (/programs/mp4box/builds/build8/bin/gcc/MP4Box+0x41ea6d)

AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV /programs/mp4box/builds/build8/src/media_tools/av_parsers.c:5730:7 in avc_parse_slice
==16957==ABORTING
```
There is a segment fault detected by AddressSanitizer
This is a GitHub Issue
repo:gpac
owner:gpac
Title : There is a segment fault detected by AddressSanitizer
Issue date:

--- start body ---
## Description
There is a segment fault detected by AddressSanitizer

## System info
```
Ubuntu 20.04.2 LTS
clang version 12.0.0-++20210402082642+04ba60cfe598-1~exp1~20210402063359.71
MP4Box - GPAC version 1.1.0-DEV-rev1705-gc3ed3094a-master
```

## Build command
```
./configure --static-mp4box --prefix=`realpath ./install` --enable-sanitizer --cc=clang --cxx=clang++
```

## crash command
```
MP4Box -dxml -out /dev/null poc_file
```

## Pocs
[poc.zip](https://github.com/gpac/gpac/files/8000905/poc.zip)


## Crash output
```
==16957==ERROR: AddressSanitizer: SEGV on unknown address 0x62d000142554 (pc 0x00000093684b bp 0x7fff830b8310 sp 0x7fff830b8180 T0)
==16957==The signal is caused by a READ memory access.
    #0 0x93684b in avc_parse_slice /programs/mp4box/builds/build8/src/media_tools/av_parsers.c:5730:7
    #1 0x93684b in gf_avc_parse_nalu /programs/mp4box/builds/build8/src/media_tools/av_parsers.c:6142:9
    #2 0xcda24e in gf_inspect_dump_nalu_internal /programs/mp4box/builds/build8/src/filters/inspect.c:1068:9
    #3 0xcd8b3f in gf_inspect_dump_nalu /programs/mp4box/builds/build8/src/filters/inspect.c:1222:2
    #4 0x4f4863 in dump_isom_nal_ex /programs/mp4box/builds/build8/applications/mp4box/filedump.c:1288:5
    #5 0x4f8170 in dump_isom_xml /programs/mp4box/builds/build8/applications/mp4box/filedump.c:2001:9
    #6 0x4e0da8 in mp4boxMain /programs/mp4box/builds/build8/applications/mp4box/main.c:6171:7
    #7 0x7f99dcef20b2 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x270b2)
    #8 0x41ea6d in _start (/programs/mp4box/builds/build8/bin/gcc/MP4Box+0x41ea6d)

AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV /programs/mp4box/builds/build8/src/media_tools/av_parsers.c:5730:7 in avc_parse_slice
==16957==ABORTING
```
--- end body ---
