Patchy artifacts in re encoded video

[sanosuke]

Hi
I'm using staxrip for my encodes and recently i had been experimenting with codec settings in staxrip for getting better picture quality at lower bitrates. So i encoded a ripped movie file and the output was awesome, i could hardly see any difference in the quality but annoyingly, I notice artifacts in several 'fast-motion' and 'dark' scenes. Please help me to adjust the codec settings to ensure that such artifacts do not appear in my next encode.
I've attached a file containing some screenshots of such artifacts.

These are my encoding settings:

cabac=1 / ref=8 / deblock=1:-2:-1 / analyse=0x3:0x133 / me=umh / subme=10 / psy=1 / psy_rd=1.00:0.15 / mixed_ref=1 / me_range=32 / chroma_me=1 / trellis=2 / 8x8dct=1 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=-3 / threads=3 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / constrained_intra=0 / bframes=4 / b_pyramid=2 / b_adapt=2 / b_bias=0 / direct=3 / wpredb=1 / wpredp=2 / keyint=250 / keyint_min=25 / scenecut=40 / intra_refresh=0 / rc_lookahead=60 / rc=2pass / mbtree=1 / bitrate=617 / ratetol=1.0 / qcomp=0.60 / qpmin=10 / qpmax=51 / qpstep=4 / cplxblur=20.0 / qblur=0.5 / ip_ratio=1.40 / aq=1:1.50


Thanks in advance

[poisondeathray]

this looks like decoding errors, not encoding settings problem

what software for playback ? what decoder ? Try something else, like MPCHC, or SMPlayer - do the artifacts still remain ?

weightp is known to cause this sort of problem with some decoders, you can try disabling it

[sanosuke]

this looks like decoding errors, not encoding settings problem

what software for playback ? what decoder ? Try something else, like MPCHC, or SMPlayer - do the artifacts still remain ?

weightp is known to cause this sort of problem with some decoders, you can try disabling it

I'm using MPCHC for playback. Er.. how should i disable weightp? do you mean the weighted b-frames prediction in x264vfw settngs?

[poisondeathray]

--weightp 0

The option might not be available in the vfw version GUI , you would enter that on the extra commandline box

But ffdshow and mpchc decoders have fixed the issue with weightp, so it's unlikely to be the problem , assuming you are using recent build

What dimensions are you encoding ?

[sanosuke]

--weightp 0

The option might not be available in the vfw version GUI , you would enter that on the extra commandline box

But ffdshow and mpchc decoders have fixed the issue with weightp, so it's unlikely to be the problem , assuming you are using recent build

What dimensions are you encoding ?

ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : High@L4.0
Format settings, CABAC : Yes
Format settings, ReFrames : 8 frames
Muxing mode : Container profile=Unknown@4.0
Codec ID : V_MPEG4/ISO/AVC
Duration : 1h 33mn
Nominal bit rate : 617 Kbps
Width : 1 280 pixels
Height : 544 pixels
Display aspect ratio : 2.35:1
Frame rate : 23.976 fps
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.037
Writing library : x264 core 93 r1542 5b86182

[poisondeathray]

617 kbps is quite low for 1280x544 , it's likely contributing to these artifacts - especially if this is an action type movie with lots of motion , explosions etc..

For a typical movie with those dimensions, most people end up with 4-5Mbps , you're using 6-8x less bitrate . x264 is efficient but not that efficient! Use a higher bitrate and/or preprocess with denoising filters to lower your bitrate requirements, or resize smaller

[sanosuke]

Oh ok.
Thanks for all your help.