I am trying to use ffmpeg, kvazaar, GPAC to split a mp4 file into tiles.
Following the"HEVC Tile based adaptation guide", here is the command line and results:

```
ffmpeg  -i 008.mp4 -s:v 3840x1920 -r 30 -vf scale=3840x1920 -c:v rawvideo -pix_fmt yuv420p 008.yuv

kvazaar -i 008.yuv --input-res 3840x1920 -o 008.hvc --tiles 3x3 --slices tiles --mv-constraint frametilemargin 

MP4Box -add 008.hvc:split_tiles -fps 30 -new video_tiled.mp4

MP4Box -rem 3 video_tiled.mp4 -out test_tile_lost.mp4

gpac -i test_tile_lost.mp4 hevcmerge vout

``` 

![image](https://github.com/gpac/gpac/assets/149464349/2c63eda4-067f-48a7-8310-bd76d7dc92c8)

![image](https://github.com/gpac/gpac/assets/149464349/36b9b0cd-deb1-4f6d-8b89-8a9fb11c9e30)

What did I miss?

Any help is appreciated!

Unexpected error at Reproduce HEVC Tile based adaptation guide
This is a GitHub Issue
repo:gpac
owner:gpac
Title : Unexpected error at Reproduce HEVC Tile based adaptation guide
Issue date:

--- start body ---
I am trying to use ffmpeg, kvazaar, GPAC to split a mp4 file into tiles.
Following the"HEVC Tile based adaptation guide", here is the command line and results:

```
ffmpeg  -i 008.mp4 -s:v 3840x1920 -r 30 -vf scale=3840x1920 -c:v rawvideo -pix_fmt yuv420p 008.yuv

kvazaar -i 008.yuv --input-res 3840x1920 -o 008.hvc --tiles 3x3 --slices tiles --mv-constraint frametilemargin 

MP4Box -add 008.hvc:split_tiles -fps 30 -new video_tiled.mp4

MP4Box -rem 3 video_tiled.mp4 -out test_tile_lost.mp4

gpac -i test_tile_lost.mp4 hevcmerge vout

``` 

![image](https://github.com/gpac/gpac/assets/149464349/2c63eda4-067f-48a7-8310-bd76d7dc92c8)

![image](https://github.com/gpac/gpac/assets/149464349/36b9b0cd-deb1-4f6d-8b89-8a9fb11c9e30)

What did I miss?

Any help is appreciated!

--- end body ---
