Only call av_register_all() if using legacy versions of libavformat Add a preprocessor #define to ensure we only call av_register_all() when working with libavformat versions older than 58.9.100. The function was removed entirely in ffmpeg 5.0.
Print apostrophes instead of acute accents in loudgain.1 This manual page uses the \' groff sequence to print acute accents, when it should just print apostrophes.
