[FFmpeg-user] ffmpeg ac-3 encoding speed

[Davor Josipovic]

I am encoding “dts (DTS), 48000 Hz, 5.1(side), s16, 1536 kb/s” to “ac3,
48000 Hz, 5.1(side), flt, 640 kb/s” with this command:

ffmpeg -i %tmp_orig_audio% -c:a ac3 -ab 640k -q:a 0 %tmp_enc_audio%

Now, on an Intel i3 machine using only one core, approximately 60sec of
this DTS stream is converted each second. It is almost as fast as the disk
can write and read.

Is this encoding speed normal or am I doing something wrong? I remember
that encoding stereo with LAME on high compression was much much slower. So
I wonder whether the quality of the resulting AC-3 stream is optimal? Can
it be tweaked?