AMV size

Lyrs · Post by **Lyrs** » Thu Oct 03, 2002 4:26 pm

Wow, I haven't seen Alumini is a long time...where have you been? Wait, I'll just checked out your site for that info.

Anyway, to the topic at hand. I haven't ripped any serious DVD footage yet, but I do have a cople gigs of Counter-strike footage that I recorded. 1.6 gigs for about 3 minutes. Resolution: 1024 x 768, but I had to change that to a much more manageable resolution.

Lyrs

Zarxrax · Post by **Zarxrax** » Thu Oct 03, 2002 4:37 pm

Aluminum: yes, you should use YUY2 mode, as it compresses significantly better than the RGB. And yes, it is also lossless in that it introduces no artifacts, only loses some color info. However when you compress your video for distribution, mpeg or divx or whatever you will use are going to through out that color info anyways, so you arent really losing anything at all by using YUY2.

Big Big Truck · Post by **Big Big Truck** » Thu Oct 03, 2002 4:54 pm

I use HuffYUV. Will look into YUY, though, thanks for the suggestion.

RadicalEd0 · Post by **RadicalEd0** » Thu Oct 03, 2002 5:05 pm

Yupp, like I said, YUY2 mode
mostly because it compresses 2x more than rgb, is generally lossless unless you're recompressing several times, and because that way the vid never leaves the YUV colorspace except during editing.

RadicalEd0 · Post by **RadicalEd0** » Thu Oct 03, 2002 5:09 pm

Big Big Truck wrote:I use HuffYUV. Will look into YUY, though, thanks for the suggestion.

o err.. we're all talking about huffyuv, its just theres a YUY2 compression mode (under the RGB compression method drop-down box) which yields twice the compression without any real quality loss.

AbsoluteDestiny · Post by **AbsoluteDestiny** » Thu Oct 03, 2002 6:05 pm

You should never do colourspace conversions. If you think that there is no real loss then you might find this interesting.

If I use HuffYUV in YUY2 mode for each coversion and did as follows:

- Ripped a dvd and made HuffYUV clips in virtualdub in Full Compression mode
- Edited in Premiere
- Prerendered a section in HuffYUV and put it back in the timeline
- Exported whole amv to HuffYUV
- Compressed the final encode in virtualdub using Full Recompress mode

that would all be "lossless" except for the last compression wouldn't it? No - it is VERY lossy. Look at this example:

http://www.absolutedestiny.org/yuy2rgbconversion.jpg

The first image here is the source, the second is the final image and the bottom image is the difference between the two.

You'll notice that in the 2nd image you can see that

a) Both top and bottom subtitles have faded
b) The background has become more like grey
c) The kanji now has a dark red shadow at the edges

and so on. The third image shows all the colour that has been lost and it is quite substantial really considering that you are hoping for it to be lossy. This is not an uncommon editing procedure for some people either but remember that just because you are using HuffYUV doesnt mean that everything is lossless as it will do a colourspace conversion every time it is given data as rgb.

Virtualdub Full Processing and Premiere work in RGB so everytime you use those you convert the colours. Also vfapi plugin uses RGB as well.

So, if you are using an RGB process - use HuffYUV's RGB mode wherever possible... it might be bigger but it will look better in the long run.

RadicalEd0 · Post by **RadicalEd0** » Thu Oct 03, 2002 6:31 pm

eliminate vfapi and full processing because they are unnecessary for any amv I've ever done and you've got 1 conversion from yuv to rgb and back. Converting that picture 1 time can't possibly do extremely noticable visual damage and plus the effects of colorspace conversions are much more obvious on pure red text against a set color background than on actual video material (even if it is drawn anime). Not that the loss isn't a bad thing.. its just that its kind of too minute (normally) to get excited about.

AbsoluteDestiny · Post by **AbsoluteDestiny** » Thu Oct 03, 2002 6:58 pm

RadicalEd0 wrote:eliminate vfapi and full processing because they are unnecessary for any amv I've ever done and you've got 1 conversion from yuv to rgb and back.

Um... I'm aware of this.

However, many people will use the method shown above. I just made the example to point out that you can't put too much faith in the fact that you aren't losing "much" information. Many users do not realise that Full Compression mode will convert things to RGB before writing the avi file... and equally many users wont appreciate the difference anyway ^_^

I try and do as few colourspace conversions as possible - usually you will only need to do 2 (one from YUY into RGB duringediting and another from RGB to YUY for a divx distro) or 3 if you encode an mpeg with tmpg.

it was just an example

RadicalEd0 · Post by **RadicalEd0** » Thu Oct 03, 2002 7:07 pm

'ts all good 8)
you also don't have to go 3 conversions when encoding to mpeg if you output in YUV and encode through avisynth (unless tmpg for some reason has to switch it to RGB before encoding, which would be a waste

)
thats afaik

AbsoluteDestiny · Post by **AbsoluteDestiny** » Thu Oct 03, 2002 7:23 pm

RadicalEd0 wrote:(unless tmpg for some reason has to switch it to RGB before encoding, which would be a waste )

You're right - it would be a waste... and that's exactly what it does ^_^;;;