H.264 streams with not seekable I-frames

[eumagga0x2a]

Old (older than autumn 2014) Avidemux versions suffered from an issue when remuxing H.264 transport streams to MKV or MP4 that all I-frames became not seekable. Now we've got a nice sample

https://we.tl/m0a253i6qZ

showing at least a similar if not exactly the same problem. It would be great to be able to avoid reencoding, saving old treasures in their full quality.

Reference: Große MKV: keine I-Frame-Navigation

[eumagga0x2a]

Fixed by [mkv/h264 info] Optionnaly keep the recovery time in case it is not duplicated every time. It helps finding IDR frame masquerading as NON IDR frame + recovery=0, thanks a lot!