Blotched color - EQM_V3EHR + xvid 1.1.0b2 + mencoder

[mwahal]

Hi,

I downloaded Sharktooth's EQM_V3EHR matrices for converting high definition recording to xvid. I'm using linux 2.6.12.1 (debian/KnoppixMyth), mencoder latest (CVS build) and xvid-1.1.0-beta2.


Number of passes = 2
Bitrate = 6000
Parameters passed to xvidoptions.
trellis:chroma_me:chroma_opt:hq_ac:vhq=4:par=ntsc169:bvhq=1:max_bframes=3:quant_type=mpeg
Video filters : hqdn3d=2:1:6,pp=ci [cubic deinterlacing]


Hardware Platform to display xvid: IOData LinkPlayer2

No scaling or zooming is done, the aspect and the frame size is left intact.
I'm doing cubic deinterlacing[pp=ci], but removing that didn't make any difference in the color.

[I did remove trellis based on some xvid bug with EHR matrices, but that didnt help either.]

I'm experimenting with high definition CSI_Miami clip in which starts with a long shot of miami beach and then camera focuses on a RED ford mustang front/hood driving on a freeway.

In the original mpeg, the color of the mustang's hood is bright red with uniformity. When I encode to xvid, I get blotchiness on the front/hood. The color is not uniform and has lots of blotches on it. You can sort of make out variousI'll try to find a way to grab an image and post it.

I also tried a 3000kbps version, but the red colors on mustang are still blotchy. When the car moves, the colors on the hood sort of move in waves up and down.

Thanks in advance

Mudit

[Sharktooth]

EHR is not intended to be used that way, the bitrate it's even too low for it... however it's not a matrix problem.
The rule of thumb is to use a LOW bitrate matrix for HD encodes, coz more pixels = more bits and if you want to keep a good compression you need a low bitrate matrix.

[mwahal]

Sharktooth,

I did try your HR, UHR, at 3mbps, 6mpbs. Also, tried your EHR at 9mpbs. Cant get any satisfactory results.

Shall I add more video filters such as deblocking, deringing, etc ? Or scale the image down to 1/2 or 1/4th the resolution ?

I've seen some xvid clips of high defn programs at half resolution and 2mpbs bitrate, and they look amazing. I simply want to achieve similar video quality using xvid.

Thanks
Mudit

[Sharktooth]

high bitrate matrices are definatly not for HD encodes... switch to a low bitrate one or h.263.
also ensure your videocard or driver have no problems interpolating colors (this may be the cause of your problem).

[mwahal]

I did switch to LR and ULR and used 1500/2000kbps. Still the colors are blotchy. I'll try another clip for experiment.

I'm using IOData LinkPlayer 2 for display (connected to Panny 50" DLP).

Thanks
Mudit

[mwahal]

At this time, I'm trying to simply backup mpeg2 to xvid, and probably save some disk space. Not looking to create a single CD backup or anything. Just want to have some decent HD like quality.

So, shall I try LR and ULR with 3-5mbps bit rate ?
Thanks

Mudit

[Sharktooth]

do a compression test and set a convenient bitrate.

[IvS]

mwahal: What is the bitrate you get? Very low bitrate may be the reason for the artifacts. Personally, I can't encode any HD content with 1.1.0 beta 2 and not get a far lower bitrate than I specify. Settings other than 2-pass work fine. (Refer to my post here (http://forum.doom9.org/showthread.php?p=734195#post734195))