Why do all my Capture MJPEG to DIVX; always look like crap?

[LanEvo7]

I've been capturing for a while now and using VBR half D1 resolution without much complaints. In looking for a better solution, I tried converting to MPEG4 Divx since in theory the quality should be better at mpeg4 than mpeg2 if the bitrate is the same. Somehow it always comes worse than MPEG2. I set mpeg2 at 2100 and it still looks better than divx at 2000.

[bugster]

My guess would be it is related to interlacing. Moeg-2 supports interlacing, divx (AFAIK) does not. So when you encode your captures to mpeg-2, the interlacing can be preserved, when you encode to divx, it needs to be de-interlaced and this can be tricky to do well. Take a look at the de-interlace filter in virtualdub, it might help.

[DJRumpy]

The DivX codecs comes with a built in deinterlacer and the pro version now supports interlaced video. You should be able to access it via the codec properties. Can you describe this 'poor' output more clearly? I've encoded a few interlaced projects in DivX without issue, and good output quality.

[LanEvo7]

I use divx 5.0.5 with interlaced enabled. At 2000 bitrate for divx, which is pretty high for mpeg 4, there are fewer problems. Everything looks fine, but my mpg2 still looks better. The interlace lines break up less often in mpg2 than in divx.

When I use lower biterates like 780, which is divx's default, I get lots of pixel breakage and the colors looked smeared. I thought divx might be able to give a better size/quality ratio and justify me buying an MPEG4 dvd player, but if the quality looks equal to or worse than my mpg2 conversions why bother.

[LanEvo7]

By the way, how do i select the correct aspect ratio for my divx files. Like if I encode to MPEG2 at half d1, I can select it to display at 4:3. How do I do that with Divx?

[DJRumpy]

DivX does not support aspect ratio. It's a 'what you see is what you get' format. You cannot embed a property that says 'this video is 16:9'. You simply resize it to the aspect ratio you want. If you wanted a 4:3 DivX, and the width was 640, then you would devide 640 by 1.3333, to get the new hight (1.3333 is the decimal value of 4:3 - 4/3=1.33333).

You are doing multipass for your DivX encodes right? CBR is not a good idea. If you must do single pass, consider CQ mode. Single pass CBR tends to look pixelated in DivX, unless the bitrate is high enough to counter any bit shortages. Encoded properly, MPEG-2 simply cannot compare to MPEG-4 encoding at the same bitrate.

[LanEvo7]

Thanks for all the help. 2 pass did make the difference. Now it looks much better. The problem is, it took my 5 hours to convert a 42 min MJPEG file. That is extremely long. Is there anyway to shorten the time without any hardware changes? I have an amd xp1700.