ECHO              343 ffmpeg.c                   tty.c_lflag &= ~(ECHO|ECHONL|ICANON|IEXTEN);
ECHO              224 libavfilter/af_aecho.c ECHO(flt, float,   -1.0,      1.0      )
ECHO              225 libavfilter/af_aecho.c ECHO(s16, int16_t, INT16_MIN, INT16_MAX)
ECHO              226 libavfilter/af_aecho.c ECHO(s32, int32_t, INT32_MIN, INT32_MAX)