Dark regions issue

[molerus]

Hi!

I'm recording TV series from my digital sat reciever using Pinnacle DC10. The capture by itself is ok, but when converted to XviD, the dark regions become ugly dark-green. It's not so visible on the monitor, but becomes very nasty on the TV-screen. The original MJPEG capture when output on TV is ok, just the XviD compression is shitty. In order to get rid of these regions I must level-correct film prior to encoding, but firstly it supresses some details and secondly compressibility drops by about 50%. Has anyone encountered such problem? Are there any solutions. Maybe it's the MJPEG decoder problem (I use Morgan MJPEG).

Help!!:scared:

[dilly]

I don't know much about MJPEG, but you say the problem manifests itself when you go to XviD. Maybe you have luma masking enabled - this is a feature of XviD which uses less bits for the very dark/very bright regions which the human eye cannot distinguish very well. It sometimes results in a more compressible stream, and other times results in ruining the video entirely. If you have it on, turn it off, or use it only in the 2nd pass.

Also, make sure you're using a good build of XviD (Koepi's is considered 'standard') as due to the open-source nature of XviD, unless you know FOR SURE what you're using, you don't really know what you're using - it COULD be a bug from an old version or a codec conflict. I know mixing ffdshow/Koepi/Nimo can really screw up XviD playback.

[baker]

I had a similar problem but it had more to do with capture, it was on www.vcdhelp.com I posted clips etc... but no body could help!! I ended up ditching capture!

Baker

[molerus]

Hi!

In fact there is a way to avoid uglyness in dark regions. But it is achieved at the cost of overall brightness. Namely you must load the MJPEG clip through AviSynth, setting the input colorspace in AVISouurce to YUY2. The picture becomes much darker though, but the green snots are gone. Personally I use Levels correction, set as follows:

input 0-255, gamma 1.20
output - 2-255