[FFmpeg-user] libavfilter : using amix

[Mr Artichaut]

The numbers seems good :
add 1024 samples on input 0 (44100 Hz, time=0.023220, ttime=5.410249)
add 1024 samples on input 1 (44100 Hz, time=0.023220, ttime=5.410249)
remove 1024 samples from sink (44100 Hz, time=0.023220, ttime=5.410249)

The issue is that, when my input0, which is the shortest, is finished, I
don't pull any data from the sink anymore. Every av_buffersink_get_frame
failed telling me that it needs data from input0. If I continue to write
data from input 1 it doesn't use it and instead keeps asking for data from
input 0.

My amix filter is configured with "duration=longest" but it's the same
thing with shortest.