[Libav-user] Container duration

[Yuriy Pryyma]

I have some question regarding duration

1)Why we are adding "magic" 5000 to AVFormatContext duration in 
av_dump_format function?

See here

https://github.com/FFmpeg/FFmpeg/blob/9b79c65ec06f2bbe4f44c615b9df70db23126250/libavformat/dump.c#L576

2) How to set container duration longer then stream duration? Because as 
I understand it is deduced from streams durations

3) How duration is calculated if stream have not zero start 
time(frame.pts > 0). So stream start 1 second afther beginning and  have 
duration 2 seconds. So video will have duration 3 seconds? But if using 
example muxing.c I set ost->frame->pts = 60 + ost->next_pts++. Duration 
was the same(tested with avprobe) but video actually played longer then 
10 seconds.