[FFmpeg-user] Use multiple lavfi input generators

[Elliott Balsley]

I’m having trouble figuring out the syntax for this.  I want to generate a test file using video testsrc and audio sine wave.  I can do both separately, but how can I get both together?

ffplay -f lavfi -i testsrc=s=1920x1080 (this works)
ffplay -f lavfi -i sine=frequency=800 (this works)

ffplay -f lavfi -i testsrc=s=1920x1080 -i sine=frequency=800
Argument 'sine=frequency=800' provided as input filename, but 'testsrc=s=1920x1080' was already specified.

ffplay -f lavfi -i testsrc=s=1920x1080,sine=frequency=800
[lavfi @ 0x7faf0e821400] Too many inputs specified for the "sine" filter.
testsrc=s=1920x1080,sine=frequency=800: Invalid argument