Remuxing a segment of videos with updated pts/dts on packets stopped working at version 14

[ciuncan]

We are accessing RTSP streams and depending on the events, we mux the packets into a new output container to record some segments. We create an mp4 output container and create a video stream in it with the new .add_stream_with_template, providing the original input container's video stream. We then copy the packets by creating a new Packet and using .update method to copy the contents of original packet into the new one then update time_base, pts and dts by shifting the values so that initial packet starts with pts 0.

This method was working with previous versions but it stopped working when we upgraded to version 14. Trying to play with ffplay gives many No frame errors, investigating the packets from the written video file show that they are all zero sized.

Downgrading 13.1.0 makes it work again. Let me know if you need further information.