Anamorphic Encoding in x264

[Akai-Shuichi]

Could anybody direct me to a guide on how to do this, or even explain to me?

I use this site: http://ps-auxw.de/cgi-bin/ar-calc.pl?source=show
to get the info for the --sar command in x264. When I do it for 16:9, it works fine. But for 4:3 it completely goes haywire.

For example, I have a DVD that i crop to 706x480, how would I anamorphically resize this?

[aedipuss]

x264 is mostly a square pixel format. resize rather then try anamorphic as most hardware devices won't handle it. so a 4:3 dvd should be 640x480.

[poisondeathray]

--sar 10/11

Because 4/3 =~ 706/480 x 10/11

Display Aspect Ratio = Frame Aspect Ratio x Sample Aspect Ratio

(beware, these terms can have different names, but the meaning is the same)

It can be thought of as:
DAR = (w:h of the frame size) x (w:h of the pixels)



Use search, this has been discussed many times before

[hello_hello]

Try this: YodaResizeCalculator
It's also handy if you want to adjust the cropping to use a particular resolution or aspect ratio without distorting the picture.
There's an option to use ITU resizing which I think is selected by default. Generally I don't use ITU resizing because in my humble opinion I don't think many DVDs do either. At least not these days.

I've pretty much always used anamorphic encoding for DVDs but lately I've been having a serious re-think. If it was just myself playing my encodes it wouldn't be a problem as I use a PC as a media player, but not all the devices in the house support anamorphic MKV/MP4 video and display it as though it has square pixels. A couple of Bluray players do, one doesn't, two of the media players in the TVs don't, one does..... it's a little annoying.

So these days I'll probably just resize "up" (ie, cropping aside, I'd resize to 852x480 for 16:9 NTSC). The file sizes increase a bit but it's possibly worth it to eliminate the "will it display correctly" issue. If you're encoding PAL video it might be worth resizing down a bit to keep the file sizes under control as 1024x576 worth of resolution can take them close to 720p territory. That's probably why I've stuck with anamorphic encoding for so long..... I live in PAL-land.

[jagabo]

For example, I have a DVD that i crop to 706x480, how would I anamorphically resize this?

It doesn't matter how much you crop the frame, individual pixels still have the same aspect ratio. If it's 4:3 DVD --sar=8:9. If it's 16:9 DVD --sar=32:27. Avoid using less than mod 4 frame sizes. It's best to stick with mod 8 or mod 16.

If you source was originally video tape it's more likely --sar=10:11 or 40:33. Why? Because there's a discrepancy between the DVD spec (the DAR is the entire 720x480 frame) and the ITU digital video spec (the DAR is the inner 704x480 portion of the 720x480 frame). In general the studios that produce DVDs from analog tape ignore this difference.