ffmpeg time duration option -t not respected if -fflags nobuffer is used with HLS

[cjaone]

Summary of the bug:

If -fflags nobuffer is used, the output stream will be shorter than specified by the -t <duration> option.

If -fflags is omitted the length of the recording will be exactly <duration> seconds.

How to reproduce:

% time ffmpeg -report -fflags nobuffer -i https://mcdn.daserste.de/daserste/de/master.m3u8 -y -loglevel error -c copy -t 10 0.ts

Above URL may not work for you, could be geolocated (Germany).

Resulting file "0.ts" (not attached to this ticket) has playing duration of 6 seconds (expected: 10 seconds).

Without the "-fflags nobuffer" the duration is 10 seconds.