Why use Full Processing Mode in VDub?

[Davop]

When i do direct stream processing, i get smaller files, it takes less time and is better quality files then when i do Full process and use a codec like XviD. The movie has the little lines in it like in an Mpeg-2 file, but those are really only noticable during the credits. Any reason i should do full processing mode?

[Davop]

awww man... i found out the hard way. You have to keep the VOB files if you dont use full stream?

[Robert Simandl]

If you need to crop out black bars (say you recorded a 4x3 letterboxed avi and you want to convert it to a 16x9 avi), you can only do that in full processing mode.

Also, if your source is DV, full processing with an mpeg-4 codec will give you a significantly smaller file than direct stream processing.

[celtic_druid]

I would never use full processing mode as it means converting to RGB24. Always direct streaming or fast recompress. If you have a MPEG2 source though then directstreaming will simply result in RAW output.

[Davop]

Well i was ripping a DVD as an AVI. And when i deleted the VOB files the video went blank but there was still audio

[junkmalle]

Direct Stream Copy simply copies the input video stream to the output. The video is not maniplated at all (no filters, no resizing, no cropping, no changing codec, etc.)

Fast Recompress uncompresses the compressed video but leaves it in a YUV colorspace. This allows you to change the codec (or compression parameters with the same codec) but you still can't filter, resize, crop, etc. You get slightly less loss of color accuracy using this mode.

Full Processing Mode uncompresses the video to YUV colorspace, then converts to RGB. All the filters require this mode, so if you want to filter, resize, crop, etc. you have to use Full Processing Mode. For output RGB is converted back to YUV and then sent to the codec for compression.

The conversion from YUV to RGB and back is not completely losses and takes time. If you're not going to use any filtering you should avoid Full Processing Mode.

[celtic_druid]

In recent versions of VDub and VDubMod with fast recompress you can keep the entire process in YV12, so no loss of colour accuracy. If you need to resize, etc. though you need to use AVISynth.

[absinthecarolinas]

Does this mean that when I send scripts to VDub for compression to, for instance, XviD, I should really be using "Fast Recompress" instead of full processing mode? In other words, if all my filtering, resizing, cropping, etc. is done in the script and no VDub filters are used, you're saying fast recompress is more accurate/faster?

Oh, and what is "normal recompress?" I've always wondered what the normal and fast recompress options were for ...

-abs

[junkmalle]

Normal Recompress decodes the the incoming video to RGB but doesn't allow any filters to be used. This probably avoids a little processing to setup for the filtering pipeline. You would want to use this if your output codec doesn't support YUV video as a source.

If you've handled all your video processing in AVISynth you should be able to avoid RGB conversion within VirtualDub -- unless your output codec only supports RGB.

[absinthecarolinas]

Okay, so it sounds like the "fast" option is the one to go with for DVD (or whatever)-to-XviD/DivX conversion, right? That would not convert it to RGB, and if necessary couldn't you stick a "converttoyv12()" at the end of your script?

I've always used full processing, thinking that was the way to go.

-abs

[junkmalle]

Okay, so it sounds like the "fast" option is the one to go with for DVD (or whatever)-to-XviD/DivX conversion, right?

Yes, as long as all your handling in AVISynth is in YV12 colorspace.

That would not convert it to RGB, and if necessary couldn't you stick a "converttoyv12()" at the end of your script?

If you have to add converttoyv12() your video has already been converted to RGB and the damage is already done (YV12 to RGB conversion) or your original source was RGB (a computer generated animation for example). In either case it doesn't really matter who does the conversion back to YV12. It might be a little faster done in AVISynth because then you would be passing less data to VirtualDub.