Artifact issues with VP6 codec

[KeyMs92]

Hi,

I'm experiencing occasional artifact issues when reencoding VP6 flv files. The artifacts seem to occur on the 'active' bits in the video, i.e. the elements that are stored in the keyframes (e.g. backgrounds) are unaffected.

More specifically, I'm using the VP6 6.4.2 VFW codec in VirtualDub, set to VP62 (Heightened Sharpness Profile) using these settings. I didn't touch any advanced settings. I'm using two passes of which the second one is "Best Quality". Finally, I also have a rotate filter enabled and I'm using Smart Rendering (to be able to join the videos with the ones that weren't reencoded).

Here's some info about the video:

Video
ID                               : 0
Format                           : VP6
Format profile                   : Heightened Sharpness
Codec ID                         : VP6F
Codec ID/Hint                    : On2
Duration                         : 1mn 18s
Bit rate                         : 403 Kbps
Width                            : 512 pixels
Height                           : 288 pixels
Display aspect ratio             : 16:9
Frame rate                       : 25.000 fps
Bits/(Pixel*Frame)               : 0.109
Stream size                      : 3.75 MiB (99%)

[poisondeathray]

use a higher bitrate or better compression. VP6 was notorious for keyframe popping where you would get pixellation ("keyframes" as in I-frame)

[KeyMs92]

I'll try a higher bitrate. Unfortunately I must use the VP6 compression, since I'm using the smart rendering method to split the videos, i.e. the reencoded files must be able to join with the original/not-reencoded files. It's pretty bad though. You'd think such ugly artifacts wouldn't occur at all! :P

[poisondeathray]

In my tests, smart rendering only works correctly with xvid/divx in vdub . Other VFW formats have problems and errors. It's work in progress . So if even using a higher bitrate doesn't work, it might be vdub issue

[KeyMs92]

Alright, I narrowed it down to the problem. It seems that if you higher the sharpness (only available in the profile I use) to about 8, on a scale of 1 to 10, the artifacts become noticeable. It's seems quite random but true :P