An old question about SAR

[Floatingshed]

I know many people have asked about SAR, I have googled a lot and found so much conflicting information that I am now more confused!

My scenario: Two sizes of video for playback on my media player:
720x576 and 720x404

My question: What should the SAR be set to when encoding with x264?

Thanks.

[sneaker_ger]

Note that this is kind of a disputed topic and there is no clear "correct".

[Ghitulescu]

How did you get 404 scanlines?

[hello_hello]

Originally Posted by Floatingshed

I know many people have asked about SAR, I have googled a lot and found so much conflicting information that I am now more confused!

My scenario: Two sizes of video for playback on my media player:
720x576 and 720x404

My question: What should the SAR be set to when encoding with x264?

Thanks.

What's your definition of SAR? It can refer to "storage aspect ratio" (resolution) but for x264 it also refers to "sample aspect ratio" which is another term for pixel aspect ratio.

There's a list of sample aspect ratios here. The ITU and MPEG-4 SARs are very similar and the MPEG-4 SARs are easier to remember. If in doubt, I go with ITU/MPEG-4 SARs for 4:3 DVDs and the generic SARs for 16:9 DVDs, but there's no hard and fast rule.

For your examples.... the 720x576 video could be encoded at 720x576 while setting the appropriate SAR so it'll display as 16:9 (or 4:3) on playback. I assume the second example is a 720x576 16:9 video resized to 16:9 dimensions (or very close to at 720x404) before it's encoded, in which case the SAR would be set to 1:1. If you resize to square pixel dimensions you could probably retain more detail by resizing to 1024x576 instead and the SAR would still be 1:1.
Which method you use might depend on your media player. If it doesn't display anamorphic encodes correctly you might need to resize to square pixels when encoding.