[FFmpeg-user] How to select x264 preset when do ffmpeg 2-pass encoding is helpful for quality ?

[Lou]

On Mon, 7 Oct 2013 19:04:36 +0800
littlebat <dashing.meng at gmail.com> wrote:

> A question: If a slower preset is helpful for the quality at a
> specified bitrate when do a 2-pass encoding with libx264 encoder?

Sorry, but I don't quite understand the question.

> For example: select "ultrafast" in pass 1 and "veryslow" in pass 2, or,
> select "ultrafast" for both 2 passes?

You should use the same preset for both passes to avoid errors such as:
[libx264 @ 0x20ac580] different weightp setting than first pass (1 vs 2)

Note that the first pass should have "turbo" settings applied (disable
slower options generally not useful for first pass) unless x264 option
--slow-firstpass is used (maybe there are some exceptions).