File 'output.mkv' already exists. Overwrite ? [y/N] y
No pixel format specified, yuv444p for H.264 encoding chosen.
Use -pix_fmt yuv420p for compatibility with outdated media players.
[atempo @ 0x2c5ac60] Value 4.000000 for parameter 'tempo' out of range [0.5 - 2]
Last message repeated 1 times
[atempo @ 0x2c5ac60] Error setting option tempo to value 4.
[Parsed_atempo_0 @ 0x2c5aba0] Error applying options to the filter.
[AVFilterGraph @ 0x2c59da0] Error initializing filter 'atempo' with args '4'
Error opening filters!