Image coding with x264

[benwaggoner]

So, I'm finally working on a project involving H.264 I-frames as a still image codec for use in Silverlight. x264 is the encoder being used, with all the images being packed as frames in an .mp4 file.

I was wondering if anyone has played around with this scenario before and found some good settings. I'm using these parameters as my starting point:

--level 4 --preset veryslow --tune film --crf 19 --keyint 1 --slices 1

Obviously not having any kind of interframe coding simplifies things a lot!

[nm]

--tune film
There's also --tune stillimage which sets:
--aq-strength 1.2 --deblock -3:-3 --psy-rd 2.0:0.7

[benwaggoner]

There's also --tune stillimage which sets:
--aq-strength 1.2 --deblock -3:-3 --psy-rd 2.0:0.7
Ah! I'd forgotten about that.

Can anyone involved share the thinking/goal behind those particular psychovisual settings? It seems there's going to be a pretty huge coding efficiency hit with such low in-loop deblocking parameters. Perhaps this is meant more for high quality photo archiving?

My target here is getting as small as possible for "good enough" content used in internet delivery. Like something around JPEG quality 60 maybe.

[Dark Shikari]

Ah! I'd forgotten about that.

Can anyone involved share the thinking/goal behind those particular psychovisual settings?If there is no motion, temporal artifacts are irrelevant, thus we can jack up psy settings to 11 and get away with it.

It seems there's going to be a pretty huge coding efficiency hit with such low in-loop deblocking parameters.It's not an in-loop filter if you don't have interframes.

In still-image coding, where there is no coding efficiency effect of deblocking, weaker deblocking is preferred for psychovisual reasons.

Perhaps this is meant more for high quality photo archiving?That doesn't even make any sense. At lower QPs, deblock strength goes down on its own.