PDA

View Full Version : Resizing/cropping question...


kikker
22nd May 2007, 02:02
I have a number of videos I'd like to re-encode for a portable device. Staxrip, for instance, will let me resize to a width of 320 and a height, which should be a multiple of 16 for best quality. That's fine. What I don't understand is why Staxrip complains that the aspect ratio of the re-encode deviates presumably above some pre-determined threshold percentage from the source aspect ratio. In other words, it wants me to crop the original so that the aspect ratios of the source and the target differ by not much more than 1% or so.

Is this done to enhance the quality of the encode? Why should it care what the AR of the source is, even if it's around a 2% difference in the AR? In order to satisfy this threshold I could of course just resize the target a bit, but then I would violate the '16 rule', so I just crop the source. But, I still don't know why it's necessary.

stax76
23rd May 2007, 18:05
Next version will allow to customize the threshold. You might create a template for portable encodes using a higher threshold. Since I got a script to build and upload StaxRip you can download a development build.

http://www.planetdvb.net/non_drupal/staxrip/StaxRip_Hotfix.zip

kikker
23rd May 2007, 18:11
Oh thanks. Love your app BTW and hope you keep developing. I was just curious if there is anything to beware of when the AR of the source and target differ by more than a determined percentage.

Does the quality of the encode suffer, or does the source simply become slightly distorted? It seems the only thing to be aware of when cropping at least is to crop even pixels and keep the source mod4 for interlaced and even for progressive sources. Is that correct?

stax76
23rd May 2007, 18:42
It becomes simply more distorted, mod 4 is forced because of some DirectShow and AviSynth filters require it in certain cicumstances.