Author Topic: VOB resizing and compression  (Read 71 times)

Thyco2501

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VOB resizing and compression
« on: May 15, 2018, 01:58:59 PM »
First of all, this is my first post here so hello!

I'm currently trying to convert VOBs into MP4s, but it's somewhat tricky. The resolution of VOBs is 720x480 with anamorphic aspect ratio (pretty sure this is true for all NTSC VOBs), and it has to be changed to 853x480 to maintain proper aspect ratio. The problem is that you can't use odd numbers when resizing so the only options are 852 or 854, but you can't really use either if you want to maintain mod16. This basically means that you have to use 848x480 or 864x480. Correct me if I'm wrong, but I think the first one is the lesser of two evils because it alters the aspect ratio by only 0,59% (or 5 pixels) as opposed to 1,29% (or 11 pixels). That's when you squeeze the video, but I'd like to try cropping it now, and this is where I need help. I intend to do the following, but it's probably all wrong:

1. Resize the video to 852x480 or 854x480 (I'm leaning towards the first option).
2. Crop pixes from the sides so that the resolution becomes 848x480.
3. Resize the video to 848x480 (the same as in step #2) just so that the resize filter gets to work with mod16.

My questions are (please keep in mind that I'm not an expert when it comes to this stuff by any means):

1. Is there any preference between 852x480 or 854x480?
2. Is using the resize filter twice during the same conversion a bad idea? Does it lower the overall quality?
3. Should I even resize a second time just so that the filter gets to work with mod16?
4. How important is it to maintain mod16 for both resolution values?
5. How exactly does mod16 improve compression?

Finally, if you have any tips concerning VOB conversion as well as improving quality and/or keeping file size low, I sure could use them!
« Last Edit: May 15, 2018, 02:09:57 PM by Thyco2501 »

eumagga0x2a

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Re: VOB resizing and compression
« Reply #1 on: May 15, 2018, 03:54:18 PM »
You can keep the video anamorphic with MP4 (just use a current nightly of Avidemux) unless you have to use a crap of a video player.