How many threads does ffmpeg use by default?

As of 2014, it uses an optimal number. You can verify this on a multi-core computer by examining CPU load (Linux: , Windows: task manager) with different options to ffmpeg: (optimal); (single-threaded); (2 threads for e.g. an Intel Core 2 Duo); none (the default, also optimal). 2015 edit: on a 12-core CPU, some ffmpeg commands have Linux showing at most 200% cpu (only 2 cores), no matter what number is given to . So the default may still be optimal in the sense of "as good as this ffmpeg binary…