[FFmpeg-user] Change commands during runtime when the stream is being piped into stdin

[Joao Pedro Borges Martins]

I want to send a command to change the audio filters on an already running
FFmpeg process using the process stdin but the audio data is being passed
in the stdin itself, I tried prefixing the command with `#` but had no
success. The program just considers my command as a malformed packet and
lags the stream for a bit.

Using node js ChildProcess to handle the FFMpeg:

*> Initial args:* `-i - pipe:1 -analyzeduration 0 -loglevel 0 -f s16le -ar
48000 -ac 2`
*> Command sent into stdin*: `af=bass=g=20:f=110:w=0.3\n` (Tried # and
encoding in binary)