How to synchronize streams in FFmpeg?

Question

fmpeg

Given:

• IP camera JVC VN-H257;
  
• Linux based OS
  
• fmpeg.
  

Task:
Combine audio and video stream into one file, because the camera does not mix audio and video itself, and distributes them separately (to different addresses).
Problem:
FFmpeg for some reason opens input streams in turn: opens the first stream, buffers, then opens the second stream, buffers, and only after that it starts to mix them, for this reason, the audio / video series is out of sync within 10- 15 seconds.
Question:
How can I force FFmpeg to open all input streams at the same time, and only after that start muxing? I would like to reduce the desynchronization to a minimum, ± 1s.
Peculiarities:
Because the camera gives audio exclusively in its proprietary µ-Law format mixed with various data, then the audio stream is pulled out from stdin (with the help of a small utility I cut out the excess to get a “normal” µ-Law) + audio is encoded using libfaac during mixing. There may be additional overhead associated with this, and it may also increase desynchronization. But this moment can be omitted.

Answer 1

Try lzone.de/cheat-sheet/ffmpeg with the words "Correcting Time-Shift" and, in general, google on this topic.