[FFmpeg-user] Changing -g value while livestreaming and reencoding?

[Tim Beyer]

Dear ffmpeg community,

I am using ffmpeg in an nginx environment to reencode Livestreams on
Ubuntu.

So there are 2 Livestreams with the exact identical options going into the
reencode. Both are streaming to a server in germany - one comes from
germany, the other comes from the US eastcoast. So I have the problem, that
Twitch moans after some time about the Keyframe Interval of the stream
coming from the US.

This is the line I am using to reencode:

exec_push ffmpeg -i rtmp://localhost/input/$name -c:v libx264 -preset slow
-profile:v main -b:v 2175k -minrate 2175k -maxrate 2175k -bufsize 2175k -r
40 -g 80 -c:a aac -strict -2 -b:a 160k -f flv rtmp://server \-c copy -f flv
rtmp://server;

Does anybody have a clue what could cause this and how to prevent it?
Changing x264 cpu preset on the machine where the stream comes from to
something faster doesn't work, and the reencode-server is just at ~50%
usage with 'slow' as well.


Here my version info:

ffmpeg version 2.6.3 Copyright (c) 2000-2015 the FFmpeg developers
built with gcc 4.8 (Ubuntu 4.8.2-19ubuntu1)
configuration: --extra-libs=-ldl --prefix=/opt/ffmpeg --enable-avresample
--disable-debug --enable-nonfree --enable-gpl --enable-version3
--enable-libopencore-amrnb --enable-libopencore-amrwb
--disable-decoder=amrnb --disable-decoder=amrwb --enable-libpulse
--enable-libx264 --enable-libx265 --enable-libfdk-aac --enable-libvorbis
--enable-libmp3lame --enable-libopus --enable-libvpx --enable-libspeex
--enable-libass --enable-avisynth --enable-libsoxr --enable-libxvid
--enable-libvo-aacenc --enable-libvidstab
libavutil      54. 20.100 / 54. 20.100
libavcodec     56. 26.100 / 56. 26.100
libavformat    56. 25.101 / 56. 25.101
libavdevice    56.  4.100 / 56.  4.100
libavfilter     5. 11.102 /  5. 11.102
libavresample   2.  1.  0 /  2.  1.  0
libswscale      3.  1.101 /  3.  1.101
libswresample   1.  1.100 /  1.  1.100
libpostproc    53.  3.100 / 53.  3.100


Thanks a bunch,
Tim