Brightness issue

[pieroxy]

Hi,

I was trying to compare xvid and divx when I discovered that my xvid encodes are much brighter than my divx ones...

My process is:
1. DVDShrink (reauthor keeping only the main movie, no compression)
2. DGIndex/DVD2AVI
3. VFAPI to convert to AVI
4. VirtualDubMod

When I encode in DivX, the resulting file has the same color as the original. When in XviD, the resulting file is much brighter...

Any idea as of why?
Thanks

[breez]

What decoders are you using for playback?

[chilledoutuk]

i agree compare the video files in a media player like vlc or mplayer.

Aleternativly change the fourcc of the video files so that they all use the same decoder.

[pieroxy]

I tried with media player, and also opened it in vdubmod. Both show the same brightness difference.

In GSpot it shows that the divx file is decoded with divx and the xvid file with xvid. Should I try and make them decoded both with xvid or both with divx?

[chilledoutuk]

test them with vlc it uses its own codecs so that would hopefully rule that out.

http://nightlies.videolan.org/

[pieroxy]

Well... I could hardly believe my eyes. With VLC, the xvid file is the file matching the original. The divx file, however, is much more saturated than the original.

At least, the luminance problem is gone ;)

Edit: I triple-checked everything...

[breez]

Ok, there's multitude of possibilities why this is happening.

1) Differing output renderers between players (you can change this in settings).

When colorspace conversion is done in VMR9, video levels (black at 16, white at 235) are usually preserved. With your PC monitor calibrated for PC levels (0-255) this results in bright/washed out picture.

When overlay is used the 16-235 is usually expanded to 0-255 to conform to the display with PC levels.

2) Colorspace conversion done at the decoder or media player application.

In these cases the colorspace conversion may or may not preserve video levels and it can cause the difference.

[pieroxy]

I will now die out of shame. It turns out the "brightness" knob was pushed to the maximum in the xvid decoder settings... I honestly don't know who pushed it... Well, I'm the only one using the thing, so I must've done it, but I sure don't remember it and I reinstalled my PC a couple of weeks ago, so it must have been recent...

Weird. But problem solved. Sorry about that. :scared: :(

[celtic_druid]

Speaking of colourspace conversions. You might want to look into using AVISynth instead of VFAPI.

[raeltheimperialaerosolkid]

Well, I got the same issue while using XviD as decoder and MPC as player. Same thing happend with a stand alone player (LG DX9900) on a normal TV. The XviD encodes were so bright that everything seemed to be in the mist...;)
On th PC I solved the problem simply using VLC (well, I didn't try to use the post processing feture in the XviD decoder... I will do it asap). On the SAP I could only change the TV settings...:(