How to convert things in vitualdub...

[RadicalEd]

For some reason nobody here seems to know what the different processing modes in virtualdub do.

IF you are converting something from mpeg1, 2, any divx codec or variant thereof, and anything other than uncompressed rgb or huffyuv in rgb mode, and not doing any filtering in vitualdub, you should use FAST RECOMPRESS mode.

When you are converting from a RGB source, or using virtualdub to filter the video, are the only times you should use Full Processing mode.

Why? It's simple really, any of the above mentioned formats other than RGB operate in the YUV colorspace. Virtualdub's Fast Recompress mode also operates in YUV, as opposed to Full Processing which operates in RGB.
Thus, when virtualdub is say encoding an mpeg2 file off a DVD into XviD, in fast recompress mode the video is staying in the YUV colorspace from source to encode. When vdub is in Full Processing mode the video is going YUV -> RGB -> YUV. This is bad because it A. Slows down the process alot due to converting between colorspaces, and B. degrades the quality of the chroma planes causing color bleeding and such.

Keep this in mind when writing guides for the site, helping others, and doing your own encodes.

[geeforce]

Hi, would this apply to frameserving? eg. avi > mpeg2(tmpgenc).

Because I have noticed that virtual dub makes the mpeg2 looks as is has faint colour patches on playback.

[RadicalEd]

omg you've exhausted my incredibly deep knowledge bank

Seriously, I've never used virtualdub to frameserve. It seems to be able to do it in fast recompress mode, so I'd guess so, but I honestly don't know. I've always used avisynth to frameserve which does operate in YUY2 (and now the more precise YV12).

Although TMPG is weird in that it converts all input to RGB before encoding, reguardless of the source, meaning if you're encoding to mpeg1/2 with tmpg the yuv > rgb >yuv conversion is inevitable (much like nandub). The main place where fast recompress is almost essential is when encoding right from virtualdub into divx, xvid, or huffyuv

[Baldrick]

Thanks for the tip. Will add that to my virtualdub to divx guide.

[mats.hogberg]

Cool! And what would an "RGB source" source be?
On the other hand - I always use some kind of filter in VDub (logo, resize, subtitle) so...

/Mats

[RabidDog]

this should be in the virtualdub hints and tips section NOT the how to convert section.. it says NOTHING about actual conversion and in my opinion is a somple tip. Please move it out of the HOW_TO guides.

[Ðøn Sarcasmo]

hi , i am desperetly trying to convert my home movies i stupidly saved to mpeg1 a year or so back ...


i read what you post and noticed my colors were off from the original ... i use the mp4 codec ..(fast and full compression mode) and both look different from the original. (even at equal bitrates)

also ... ive tried using other codecs to re encode my mpgs such as XviD , divx 3-5 and fast and slow motion and none of them work for different reasons ...

xvid / divx 3-5 wont start at all ... (although i know my xvid (and some of my divx) codecs are installed and work to encode otehr formats)

the only divx versions that work are the fast and slow motion options , both of which produce horriable video quality

So i guess my question is ... have they resolved this issue of the yuv / rgb in any newer versions of Vdub? or do you know any other app that could help with this problem ? I mean thats sounds pretty stupid to me , eitehr i should be able to filter my fast recompress , or i should be able to do full compression in yuv ... what the heck were they thinking? (rhetorical :P )

and how big of a problem is it ? cuz you say that doing it the fast recompress way will give better color quality ... as far as i see it fast and normal encoded videos look almost identicle to each other... and completly differnt to a trained eye from the original file... is it just an unavoidable terrable reality that there will always be some color loss?

any reponse or tips you think of sharing would be SOO appreciated ... thanks alot in advance

PS , go easy ... im newb

[maniktushar]

Does this apply if I use only like 1 filter for resize and cropping in converting VCD to DivX

[YnoT]

So for converting DVD to XVID or DIVX with VirtualDub, only use Fast recompression

what kinda format to use Slow recompression?

thanks

[manono]

Hi-

what kinda format to use Slow recompression?

There is no Slow Recompression. You mean Full Processing Mode (which also happens to be slow).

If you use VDub's filtering or frameserving, you're stuck in Full Processing Mode and the RGB colorspace. Better to frameserve using AviSynth. Let it do any necessary color conversions (when frameserving to CCE or TMPGEnc, for example).

Even more than 2 and a half years after Radical Ed's original post, many people around here are still promoting VDub filtering and VFAPI frameserving.

[mats.hogberg]

I think the problem is, it's much easier to explain how to do VDub frame serving to a n00b, than to teach him/her how to write AVS scripts!

/Mats

[manono]

Hi Mats-

You're right, of course, and you make a good point. But if you assume a newcomer is serious about his video encoding, and is willing to do his homework by reading and learning (a big assumption, I'll grant you), then it's only logical to make AviSynth one of your most important tools when doing the things for which it was designed. If someone coming here for the first time wants it all handed to him, then I, for one, haven't much sympathy for him.

And it's not as if the information is so hard to find or learn or use. AviSynth.org is, of course, the place to start. The documentation that comes with the DGMPGDec package (necessary for DVD backups into a number of formats) tells you how to use it and set up scripts. FitCD will set up basic scripts for you. And GKnot will set up much more complex scripts, allowing for IVTC and all kinds of other filtering. I recommend GKnot's automatic scripting for newcomers, as it makes it all so easy. For AVI and DVD backups I still use it for my MPEG2Source line, as well as for cropping and resizing for AVI, which I then add into my basic template scripts, and for getting bitrates. There's a bit of a learning curve, as there is for most things worth knowing, but the payoff can be huge.

[YnoT]

thanks for the advice guys.