This guide assume basic knowledge of Avisinth, DGIndex, x264, and x264 cli. (You Can Use MeGui to enter command lines). Also if you can't make sense of my writing then know this: I am no english major. Also this guide was written using a source with a 720x480 frame size as an example. If you have a 704x420, 4:3, or PAL frame size you will need to resize and input the correct aspect ratios according. Refer to the links at the bottom of the post.
An NTSCDVD comes in two flavors: 704x480 or 720x480. On playback the video plays at a resolution of 853x480. Whenever you want to resize to 853x480 in avisynth you can't. Avisynth can only handle resolution of mod2, mod4, mod8, and mod16. 853 does not fall under any of these categories. Naturally, in order to achieve this resolution you resize to either 852(mod4)x480(mod16) or 854(mod2)x480(mod16) and call it close enough. This approach is not good enough since it does not give the exact picture size of 853x480. However, we have a tool that goes by the name of x264. This tool has a custom command line(-- sar). By using this you can easily achieve the correct picture size of 853x480. How do you use this? You might ask. Well its simple, you just have to know the frame size of you source. I will take 300 for example. After you run it through DGIndex you should get a .d2v file. Open this file with notepad. And see where it says Picture_Size. For 300 it is 720x480. OK. So now you know the resolution of you source material.
Now for the encoding stage:
So, you want to encode anamorphic? EASY.
Part 1- I Don't Crop
If you do not crop then it will save you an extra step or two when it comes to producing the avisynth script. Just apply your filters and DO NOT RESIZE. You will be encoding at a resolution of 720x480.
Part 2a- I Crop
Lets say that you don't like black bars at the top and bottom of you video, what do you do? Crop of course. In my case I have:
Crop(0,58,0,-62) NOTE, YOU HAVE TO USE EVEN NUMBER WHEN CROPPING.
OK, i managed to remove 58 pixels off the top of the frame, 62 pixels from the bottom, 0 from the left, and 0 from the right. My new resolution is now 720x360 (58+60=120)[480-120=360]. This means that in my final encode i will not have black bars at the top and bottom of my movie. DO NOT RESIZE. You will be encoding at a resolution of 720*360
Part 2b- What if I need to crop the sides too? If you crop the sides you might want to resize unless you like doing algebra (Even then you probably don't have the software or hardware necessary do derive an exact number). For example if my script says: Crop(4,58,-8,-62) This means I took off 58 pixels off the top of the frame, 62 pixels from the bottom, 4 from the left, and 8 from the right. My new resolution will be: 708x360. What you want to do now is resize back to a resolution of 720x360. Just choose your favorite resizer.
A note of caution, when you crop the black bars off, DO NOT resize back to 720x480 or you will get a messed up aspect ratio. Keep the vertial pixel count as it is. Also do not resize to something other than 720(or 704) or else the aspect ratio will become messed up.
How to Configure x264-now its time to configure x264 encoder. As I said earlier there is a custom command line (--sar) that you will need to input. By default (as i understand it ) the sar is set to 1:1, this means that whatever resolution you put in will come out the other end. What you want to do is change sar. Below are a few refer to the links a the bottom for more.
For a 720x480 (16:9) NTSC DVD the correct ratio is 32:27
For a 704x480 (16:9) NTSC DVD the correct ratio is 40:33
In my case for a frame size of 720x480 I will add this to x264(--sar 32:27) After I finish encoding a video i will get video with correct aspect ratio and DVD resolution of 853x480. (How do you derive 853 you ask well 720*32=23040| 23040/27=853.333333333333[technically this is the true DVD horizontal pixel count])
If I cropped the black bars off i will get a video of resolution 853x360 at the end of it all, same thing if you cropped black bars and sides.
For more information refer to these two links. These guys probably know a lot more on the subject than I.
