Changing resolution without reencoding

[hanugro]

Hi all, I got a 1hr 40m video that is about 1GB that only has 320x240 resolution. It seems that it really should be able to play at 640x480 because the size is very big for a 320x240 resolution. Is there any way to make it play with software video player automatically at 640x480 without reencoding? I know I can stretch the player but just wondering. Thanks for your help!

[guns1inger]

Most players have a simple Double Size or 200% setting. All this will do is scale up the same way that you are doing manually. If the video was encoded at 320 x 240 then that is all you have, so increasing the size won't give you 640 x 480 quality.

[AlanHK]

Is there any way to make it play with software video player automatically at 640x480 without reencoding?

A lot of software players will go to full screen mode if you double click on the image.

Otherwise, if you set up Avisynth you can write as simple AVS file that loads your video and scales it up. Avisynth's LanczosResize function gives a nicer result than most automatic scalers. You can also play with other filters that may help, such as deblocking, then sharpening... I've done that when using a source video at small size, to get a result that isn't as good as a full resolution file, but avoids the blockiness of a simple upscale.
But this does require a considerable investment in time to get you up to speed on the software.

[hanugro]

OK thanks all! When I play double size using VLC, the quality is still OK. I think making avisynth script is OK. Which one is better Lancloz4 or Spline64. I used Spline 32 with older avisynth.

Is there no editor that make resolution change for avi like that screen aspect ratio changer (forget the name of the apps)?

[guns1inger]

You cannot change the resolution of the video without re-encoding. You might be able to patch the header of some video types, but playback is often then hit and miss, as some players will get very confused by the conflicting information. I suspect the tool you are thinking of is Mpeg4Modifier.

Have a look at the KM Player. Under Options you can set the default to be to open at double size for all videos.

[jagabo]

Which one is better Lancloz4 or Spline64.

Why don't you just do some tests yourself with a script like:

src=AVISource("filename.avi")
v1=Lanczos4Resize(src,640,480).SubTitle("Lanczos4" )
v2=Spline64Resize(src,640,480).SubTitle("Spline64" )
Interleave(v1,v2)

Open that with VirtualDub and you can step back and forth between the two.

[hanugro]

OK thanks!

[edDV]

When you set your player for hardware assist, and select "full size", the display card handles the upscale much like an upscaling DVD player.

[jagabo]

Most display cards perform a bicubic resize these days. Nvidia's VMR9 output device allows for Nearest Neighbor, Bilinear, Bilinear PS2, Bicubic A=.60 PS2 (sharp), Bicubic A=.75 PS2 (sharper), and Bicubic A=1.00 PS2 (sharpest).

Lanczos4 will be a little sharper than Bicubic but not enough to make it worth reencoding (and adding a whole new generation of artifacts). And sharper isn't always better. You will be sharpening the defects (macroblocks, DCT noise) as well as the underlying video.

[AlanHK]

Lanczos4 will be a little sharper than Bicubic but not enough to make it worth reencoding

Since he was talking about using a software player, the filtering and scaling would be done inline, no reencoding to a new file.

Even my rather unimpressive machine can display such AVS filter chains in real time.

And sharper isn't always better. You will be sharpening the defects (macroblocks, DCT noise) as well as the underlying video.

Which is why I suggested a DeBlocker first.

[jagabo]

he was talking about using a software player, the filtering and scaling would be done inline, no reencoding to a new file

Ah, I see.