Directshowsource VC-1 decoding slower resizing to 720p then keeping native 1080p

[turbojet]

I'm not 100% sure if this is an avisynth, encoder or decoder problem but I'm guessing avisynth. The issue happens with libavcodec and wmv9 (direct and ffdshow passthrough) decoders. What happens is both x264 (first pass) and CCE encode slower resizing 1080p to 720p when decoding VC-1. I tested lanczos and bicubic resizing. This is the opposite of AVCHD/MPEG2 decoding behavior.

Here's some speeds decoding with libavcodec via directshowsource and lanczosresize:
x264 first pass
1080p: 30.5
720p: 22.5

CCE SP2
1080p: 1.2x
720p: 0.7x

DG NV tools show regular behavior with x264 first pass
1080p: 32.2
720p: 45.8

but not with CCE SP2
1080p: 2.3x
720p: 1.7x

x264 2nd pass and crf encoding show regular behavior (720p faster then 1080p)

I've tested on 3 different boxes with the same behavior, could someone who understands the avisynth code take a look at it?

[Adub]

Uh, you want to actually post the Avisynth code for us to look at?

[turbojet]

I'm too naive to know for sure what code is affecting this but I would guess it's in directshowsource.cpp which seems to have some other bugs as well.

This is using avisynth 2.58, if it came across to you as me posting bugfix it's not, it's a bug report.

[Blue_MiSfit]

Yeah, it's impossible to figure anything out without more details.

We need your script, and all encoding settings.

~MiSfit

[turbojet]

Script:
Directshowsource("vc1.m2ts/mkv")
LanczosResize(1280,720) or BicubicResize(1280,720)

x264 --pass 1 --bitrate

cce sp2: default aka standard which is cbr 6000

Happens on 6 different vc-1 sources I've tried. Also found out 480p VC-1 resized decoding in x264 first pass/cce is about the same speed as 1080p VC-1 decoding, it's usually around 4x the speed.

example here (http://www.mediafire.com/?gnyz5wjh2nj) to keep it simple just run vc1.cmd.

After a little more testing I found out that compressibility has a lot to do with it and the higher the bitrate the slower 1080p runs which brings it closer to 720p speeds but that still leaves ccp sp2 not affected by bitrate and dgnv's normal behavior.