mpeg2 encoding issue: overly bright image

logiquem wrote on 10/3/2006, 8:32 AM
When encoding with MainConcept from Vegas 5, i always get a slightly overly bright image by comparaison to original DV footage. (i encode with CBR 9000 baud/NTSC interlaced settings for my projects).

1. has this problem with MainConcept codec been already noted by somebody else?
2. Has this issue been resolved with Vegas 6 or 7 version?


farss wrote on 10/3/2006, 2:02 PM
Neither are the problem.
Video from most cameras overshoots the 100% mark and the player clips it at 100%.
Check your source video with the scopes set to Studio RGB and you'll see the problemo.

I use a custom color curve to correct this, there's also a Computer RGB to Studio RGB switch in the Color Corrector which I think isn't exactly what you need but it's pretty close.

My custom curve leaves anything below 0 at 0 and then reduces the gain between 0 and 110 so that at 110 the output is 100, only straight lines with one node. Seems to work very well.

corug7 wrote on 10/3/2006, 8:07 PM
Most NTSC set top players add a 7.5 IRE setup to your video, so it should look a little brighter. If you encoded your video with an black level of 0 IRE, then the set top player is actually playing back your video as it is supposed to be seen. If you encoded your video with black levels at 7.5 IRE, then your playback device is probably setting your black levels around 15 IRE, resulting in washed out blacks.

It is normal for DVD footage to play back brighter than DV footage. Here's a link to an excellent resource.

Hope this helps.

logiquem wrote on 10/4/2006, 10:23 AM
I made a direct comparaison this morning between the DV source and the mpeg2 file and they are indeed identical in term of color and luminosity rendition, so you are right, it's not a codec problem.

Reading the source you mentionned,

everything is clearer now.

The cause of the noticable difference i see between the NTSC output from my little camcorder used as a D/A converter for monitoring and the NTSC output from the DVD player can indeed be attribued to the player 7.5 IRE setup.

I also found an another cullprit : my monitor has "DVD" and "other" options on component input image setup and it seems that the "DVD" setting is precisely there to compensate a source with 7.5 IRE setup and induce a sensible general brightness reduction.

Thanks Corey and Bob for your usefull input about this issue.