resizing avi framesize

[dude112]

I've got a avi file that has a framesize of 856*480 and what i want do do is resize it to 704*396. since my dvd player can read such a large frame. I do want it to stay an avi though. is my only option to re-encode it or is there a faster way?

[Baldrick]

Yep, you must reencode. You can use autogk, virtualdub, dr.divx.

[dude112]

is the internal resize filter in virtualdub the Lanczos3 resize filter? I've been doing some searching around and see this one popping up as the best option.

[junkmalle]

VirtualDub has several resizing filters. Lanczos3 is the best for most circumstances. It results in a sharp image, relatively free of moire artifacts.

[dude112]

I've tried resizing with virtualdub but it doesn't seem to work. What i do is:
open video file, add filter and change frame size, pick compression, fast reencoding and then save avi but it's still the same frame size. I've found out that if i keep it in full processing mode it does resize but that would make the file too large. What am i doing wrong?

[junkmalle]

As you've discoverted, you have to use FUll Processing Mode to apply any filter. You need to set the bitrate on your compression codec to get the size you want.

[dude112]

Last time i saved an avi in full processing mode i got a 40 gig file from a 700 mb one and i stopped it halfway. But i tried it here and it wouldn't be such a big file. I don't really know much about bitrates so what seems to bee a good average bitrate for an avi and what's the noticable difference? It's now at 878.

thanks for the help

[junkmalle]

Last time i saved an avi in full processing mode i got a 40 gig file from a 700 mb one and i stopped it halfway.

You probably forgot to select a compression codec and got an uncompressed file.

But i tried it here and it wouldn't be such a big file. I don't really know much about bitrates so what seems to bee a good average bitrate for an avi and what's the noticable difference? It's now at 878.

There's no way to say what the appropriate bitrate is. It varies depending on the video. You didn't even say what codec you're using.

If you're using Xvid and don't need an exact file size I recommend using single pass quantization (constant quality) mode. Start with a quantization value of 3 -- at that value the output will look pretty close to the input. If the file looks like it's going to be way too big use a higher Q value (smaller file size, lesser quality). If you want higher quality and can live with a bigger file use a smaller Q value.

[dude112]

Yes I'm using XVID codec. Profile@Level AS @ LV5, encoding type single pass quantizer 4 is the standard configuration for the XVID, but I will use quantization 3 as adviced. Is there a noticable difference in quality between the different quantization besides the file size? Cause I reencoded a file once and the file turned out less then half the size of the original. I know that means a loss of quality but for the caual eye it's really hard to spot.

[junkmalle]

In my experience, at Q=3 you can see differences between the source and the compressed file if you look closely at still frames. But at normal playback speeds you don't notice them. At 4 you can see a little macroblocking at normal playback speed if you look closely. At 2 you have to look very hard at enlarged stills to see any differences.

[dude112]

I'm trying to resize a different movie but i keep getting this message

If I don't choose a compression everything works fine but that would make the file to large. I've tried scanning for errors with virtualdub without result. any idea's?

[junkmalle]

What is the final frame size? Some codecs require the width and/or height be a multiple of 2, 4, 8 even 16.

[dude112]

the original framesize was 826*460 and i wanted to change it to 725*404

[Baldrick]

Try 724x404 instead.

And read
http://forums.virtualdub.org/index.php?act=ST&f=4&t=6608&
about that error message in virtualdub.

[guns1inger]

Make sure you have the latest Xvid version as well, as have an older versio of the codec and nwer compressed file can somethimes throw VDub off track

[dude112]

What is the final frame size? Some codecs require the width and/or height be a multiple of 2, 4, 8 even 16.

Yeah that did the trick. thanks junkmalle and baldrick[/quote]