Special settings for encoding a slideshow (all frames are different)?

[naugas]

I'm about to encode a slideshow ripped from dvd, using megui/x264. Each frame is a different photo, and it seems to me that a good way to do this is to slow down the framerate so each frame/picture is shown a few seconds.

But I discovered that many rules for encoding "normal" video doesn't apply in this situation, and using the high-quality presets in megui makes the resulting video more than twice as large as the original vobs. Removing b-frames shrinks the output size, but are there other things I can do, regarding compression, quality and encoding speed? I guess everything on motion estimation can be dropped... And what about enforcing every frame to be a keyframe?

Any help appreciated!

[akupenguin]

Yes, you should force all frames to be keyframes. Once you do that, a lot of other settings (like motion estimation) become irrelevant.

I get x264 HP I-frames-only at about 1.35x smaller than lavc-mpeg2 I-frames-only for a given SSIM. (Encoding both from a lossless source, not transcoding from DVD.)

[naugas]

Ah, I see, thanks!

I was reading some posts about enforcing keyframes using two-pass and modifying the stats-file in between, but then I realized I could set the keyint settings to 1 when encoding instead.

The commandline I ended up using which seems to work well (stats to see what's happening):
x264.exe --qp 27 --pass 1 --stats stats_qp-27 --keyint 1 --min-keyint 1 --vbv-maxrate 25000 --threads auto --thread-input --progress --no-psnr --no-ssim --sar 8:9