Current frame number being processed
Frames per second (encoding speed)
Output bitrate, e.g. "2048.0kbits/s"
Total bytes written so far
Output time in microseconds
Output time as human string, e.g. "00:01:23.456789"
Duplicate frames count
Dropped frames count
Encoding speed relative to realtime, e.g. 2.5 means 2.5×
Whether this is an intermediate update or the final one
OptionalpercentPercentage 0–100 if duration is known, otherwise undefined
Parsed progress information emitted by FFmpeg on stderr. FFmpeg writes key=value lines terminated by progress=continue|end.