Bad PAL-DV Encoder/Decoder Quality in DirectShow

Hi all,

for testing the quality of DirectShow DV Encoder & -Decoder, I made a filter graph with 8 consecutive Decode->Encode stages (simply in GraphEdit). Input was a a normal PAL-DV file, output of the eight deocde/encode stages was to the video renderer.

The quality of the displayed image is very bad, with darkened stripes every 8 pixel horizontally and vertically. Also color steps appear in diagonal borders between certain color combinations, for example at red/white borders.

This seems to be not a DV-problem, since for example the same decode->encode sequence using the Mainconcept-DV-Codec does not show these problems.

I suspect that something with the color conversion routines is wrong. The native PAL-DV-format is YUV 4:2.0, but the MS DV Decoder supplies only YUYV or similar things, or RGB variants. According to the specs, the MS DV Encoder does not even know any YUV format, just RGB. So there seems to be no possibility to stay in a native YUV-format when DV material has to be processed (which would presumably reduce decoding artifacts).

Does anyone has experienced similar problems Any idea how to solve this Or is it simply not possible to get good PAL DV data using MS DirectShow decoder/encoder

Thanks for any comments/hints! - cpix