Quick query about DAR

[Irakli]

Hello, everyone.

Recently I moved from cropping+resizing->encoding strategy in my DVD backups to cropping->encoding with AR signalling.

I am encoding using x264, so I should SAR using --sar command. Now, I figured out that SAR is calculated as SAR = DAR/PAR.
OK, it is easy to calculate PAR for particular video (simply width/height). However, I am a bit confused about DAR. So could you please suggest me how do I know DAR for certain DVD? In other words, are possible values of DAR are only limited to 4:3, 16:9 and 2.35:1?

Thanks in advance.

Regards,
Irakli

[unskinnyboy]

What you referred to as PAR, is actually SAR (w/h). PAR is Pixel Aspect Ratio and for a DVD is 1.094 for PAL and 0.9116 for NTSC. As for DAR, that can only be either 4:3 or 16:9 for a DVD. What you are referring to as 2.35:1 is the AR of the source material and would have to be presented in either 4:3 or 16:9 using letterboxing and/or pillarboxing.

Please :search: to know more. Aspect ratios have been beaten to death here, many times with me included in the fray.

[Irakli]

OK, now when I did search I see where I was wrong.

@unskinnyboy
Thanks for pointing me to the right direction. Anyway, I figured out that PAR(pixel aspect ratio) = DAR x (H/W) (e.g. for DVD with DAR=16/9, PAR=16/9 x (576/720)=64:45). In x264 I need to specify --sar, but I suppose PAR should be specified under --sar option?

Regards,
Irakli

[unskinnyboy]

--sar 64:45 will work, yes. If your DVD was 720x480 (NTSC), then you would have given --sar 32:27.

And another thing, FYI, when I said SAR, I meant Storage Aspect Ratio, which is w/h of the frame. SAR can also stand for Sample Aspect Ratio, which is equivalent to PAR for x264, or any MPEG-4 format. Which is why you were able to use the PAR value for --sar.

[Irakli]

--sar 64:45 will work, yes. If your DVD was 720x480 (NTSC), then you would have given --sar 32:27.

And another thing, FYI, when I said SAR, I meant Storage Aspect Ratio, which is w/h of the frame. SAR can also stand for Sample Aspect Ratio, which is equivalent to PAR for x264, or any MPEG-4 format. Which is why you were able to use the PAR value for --sar.

Thanks a lot for your reply! And thanks for clarifying the difference between Sample and Storage Aspect Ratios.
:thanks: