Signing mp4-files with external manifest results in faulty mp4-files (not playable, mp4-box-structure broken)

tested with c2patool 0.9.12 and c2patool 0.9.3

Once I run signing of a mp4-file with an external manifest, created mp4-file shows broken mp4-structure (no moof/mdat) and playback is broken (runs fine with internal C2PA-manifest).

Here's sample:

./c2patool sample_source.mp4 \
-r http://testhost.com/test/manifest.c2pa \
-m test.json \
-f -o ext_dest.mp4

Here are the given files:

https://github.com/user-attachments/assets/805832ee-1a37-472d-853d-6a4b9d879e3d

https://github.com/user-attachments/assets/f6a3771b-9821-48b9-85da-3dc21a5a7a88

(test.json same as https://github.com/contentauth/c2patool/blob/main/sample/test.json and self signed certs)

contentauth / c2patool

Signing mp4-files with external manifest results in faulty mp4-files (not playable, mp4-box-structure broken) #280