[FFmpeg-user] Strange results with -preset

[Carl Eugen Hoyos]

2018-01-28 18:38 GMT+01:00 Cecil Westerhof <Cecil at decebal.nl>:
> I need to upload a set of videos, but before I do that I need to
> shrink them. But I get a very strange result. Of-course the preset
> veryfast is faster as faster, fast, medium, slow, slower and veryslow.
> But the strange thing is that it also create a smaller version of the
> file. My original file is 733.8 MB. It is a mts file I also convert to
> mp4. The results:
> |-----------+-------+------|
> | preset    |  size | time |
> |-----------+-------+------|
> | veryslow  |  83.8 |   52 |
> | slower    |  94.6 |   27 |
> | slow      | 100.2 |   15 |
> | medium    | 109.0 |   13 |
> | fast      | 117.7 |    9 |
> | faster    | 106.2 |    7 |
> | veryfast  |  83.2 |    5 |
> | superfast | 177.4 |    4 |
> | ultrafast | 328.5 |    3 |
> |-----------+-------+------|

While this is not the x264-user mailing list, I'd like to comment
that it seems to be a common misconception today that the
quality setting of a video encoder is the only thing affecting
the quality of the output file - this is not true.
You may get smaller files with faster encoding but they are
expected to be of worse quality. Since you did not specify a
bitrate, you cannot expect a specific output file size.
And if you need smaller files, but the encoding time is not
your biggest need, you should specify a different quality
setting.

(Since your FFmpeg version is antique, you may of course
just have found a bug.)

Carl Eugen