"x264 -tune stillimage" for normal content - it is safe?

[oxyViz]

Hello. Have a presentations material, which are mostly still images (slides directly from powerpoint) with rare and short additions of real video content.

May I use "-tune stillimage" on such mixed material or it is better do not use any preset on it? Other encoder params - "-preset veryslow -crf 18".

Asking because can't see any visual difference: no blur on images without "-tune stillimage" and no blocking on real video encoded with stillimage tune param. Only one thing that i can see is much less CPU load on decoding "-tune stillimage", because less deblocking, i think.

without tune: -tune stillimage:
deblock=1:0:0 deblock=1:-3:-3
psy_rd=1.00:0.00 psy_rd=2.00:0.70
chroma_qp_offset=-2 chroma_qp_offset=-4
aq=1:1.00 aq=1:1.20

[Dark Shikari]

--stillimage basically jacks up the psy settings very high because you can get away with it on images where temporal stability isn't an issue. Thus, sharpness and detail at the expense of stability.

For moving content it may cause more temporal artifacts than usual.

[oxyViz]

Thank you for the answer Dark Shikari.

For moving content it may cause more temporal artifacts than usual.
Okay. I'll better avoid such use. Recently know about more suitable for such case approach - multiple different SPS and PPS. Now looking how to do it with ffmpeg and libx264.