[FFmpeg-user] ffmpeg: sync audio and video stream

[Matwey V. Kornilov]

Hello,

I need help with filter concept. Basically, I would like to achieve the
following. I have two input streams (not files): audio/video stream and
second auxiliary audio stream. I would like to mix audio channel from
first input and audio channel from second input and output it as output
audio/video stream. What I failed to do is to sync two audio streams. I
would like the second audio stream be resampled onto first stream time
stamps online and missed audio be replaced with silence. I.e. input
audio/video stream has to be retransmitted as output without delay under
any circumstances. I tried to use -af asyncts filter for second input,
but this didn't help: when frames in second audio stream are missed,
then output framerate decreases.