x264 rev 999 macroblocking problems!

[Blue_MiSfit]

Hi All,

Encoding using rev 999 with the following settings through MeGUI produces very nasty blocky output!


--pass 2 --bitrate 8600 --stats ".stats" --level 4.1 --keyint 240 --min-keyint 24 --ref 3 --mixed-refs
--bframes 3 --b-adapt 2 --weightb --subme 7 --trellis 1 --partitions p8x8,b8x8,i4x4,i8x8 --8x8dct
--vbv-bufsize 30000 --vbv-maxrate 30000 --vbv-init 0.1 --threads auto --thread-input --progress
--no-psnr --no-ssim --aud --output "output" "input"


Here's the MeGUI encoding log:

---[NoImage] avis [info]: 1920x1080 @ 23.98 fps (500 frames)
---[NoImage] x264 [info]: using SAR=1/1
---[NoImage] x264 [info]: using cpu capabilities: MMX2 SSE2Fast SSSE3 Cache64
---[NoImage] mp4 [info]: initial delay 1001 (scale 24000)
---[NoImage]
---[NoImage] x264 [info]: slice I:38 Avg QP:15.99 size: 87222
---[NoImage] x264 [info]: slice P:270 Avg QP:15.70 size: 47778
---[NoImage] x264 [info]: slice B:192 Avg QP:20.08 size: 30333
---[NoImage] x264 [info]: consecutive B-frames: 34.2% 15.6% 46.8% 3.5%
---[NoImage] x264 [info]: mb I I16..4: 38.7% 57.5% 3.8%
---[NoImage] x264 [info]: mb P I16..4: 5.8% 25.8% 1.4% P16..4: 14.6% 5.4% 3.9% 0.0% 0.0% \
skip:43.1%
---[NoImage] x264 [info]: mb B I16..4: 1.5% 7.6% 0.2% B16..8: 33.7% 1.4% 2.1% direct:10.0% \
skip:43.3% L0:38.7% L1:46.6% BI:14.7%
---[NoImage] x264 [info]: 8x8 transform intra:73.2% inter:76.1%
---[NoImage] x264 [info]: ref P L0 77.2% 14.8% 8.0%
---[NoImage] x264 [info]: ref B L0 87.3% 12.7%
---[NoImage] x264 [info]: kb/s:8454.3
---[NoImage] encoded 500 frames, 5.80 fps, 8457.12 kb/s
--[Information] Final statistics
---[NoImage] Video Bitrate Desired: 8600 kbit/s
---[NoImage] Video Bitrate Obtained (approximate): 8457 kbit/s


http://img291.imageshack.us/my.php?image=snapshot20081028181248bs4.png

That's what it looks like :)

Sample coming!

The source is a 50mbps CBR MPEG-2 trailer for Journey to the Center of the Earth.

~MiSfit

[Blue_MiSfit]

http://www.mediafire.com/?sharekey=32d600f0ab3cb846d2db6fb9a8902bda

There's the source sample

If you encode it, you'll start to see _very_ nasty blocking starting around frame 83.


I did a vanilla CRF20 encode, and the problem goes away, so my money is on a VBV bug.


~MiSfit

[Dark Shikari]

--vbv-init 0.1Wait a minute, giving x264 only 10% of the total buffer size for the first I-frame is a bad idea? However could I have guessed? :p

I just tested your exact same settings here and there was no problem, on either git x264 or my latest internal build.

[Dark Shikari]

Further tests show that it is the VBV issue Gabriel recently issued a patch for, aggravated by multithreading. I only have two cores, so it wasn't really noticeable, but my local build has quantizers 12 lower on the first I-frame than the git build, so I assume the patch has resolved whatever issue there was.

[Blue_MiSfit]

Thanks! I'll make sure to update the build ASAP!

Is there a recent build with this patch applied floating around somewhere?

~MiSfit