Codecs and non-video aspect ratio? Why doesn't it always work?

[Taapo]

Hi there,

For a whole while I have been wondering about the following: when I create a music podcast, I sometimes make a video with the album covers and some text ... in a 450x450 pixel format - since the covers are all square, why not doing the same thing for the video, right?

Anyway, when exporting from for example Sony Vegas, and selecting a codec that is able to compress pretty good (a podcast takes 32GB in the uncompressed codec) I get errors. On any station I try to do it. Only the uncompressed codec is able to export 450x450, but for example Cineform Neoscene (that I can partly understand, as it is developed for DSLR use) or Lagarith (which I don't get at all) are not able to compress to this format? Why is that? Is there a reason I don't know of?

Greets,
Frank

[poisondeathray]

What errors do you get ?

Some formats work better in multiples of 16 (mod 16) depending on the colorspace, try 432x432 for instance, or 448x448

Lagarith in RGB mode should be able to render at any resolution, but lagarith isn't suitable for a streaming podcast. You would probably want to use a flash format, with h264/aac

[Gavino]

It's probably not the aspect ratio itself that is giving problems.
Most codecs require frame dimensions that are a multiple of 4 (and often require multiples of 8 or 16).
450 does not meet that requirement.

Ah - pdr beat me to it.

[Cornucopia]

Most of the standard lossy codecs, the ones in common use, work their magic by using the DCT (Discreet Cosine Transform), which partitions up your frames into blocks of pixels and processes each block. Those blocks are usually 16 pixels wide (can sometimes be 8 or 4 or 2). Some of them are constrained even further by expecting ONLY certain sizes and dimensions.
Your video is only evenly divisible by 2, so those codecs that expect Mod16 sizes will cough up your video - sometimes stretching it, sometimes (if they're programmed well) adding black padding), sometimes not working with it at all.

Just because your still/menu/thumbnail is one dimension does NOT mean you should make your video that way. There are standards out there; if you want your stuff to be well recieved by many, stick to one of those standards.

Scott

[Taapo]

Nice replies ... I heard about those division of 16, but never knew what exactly it meant. I'll try it right away! Thanks a lot!

[jagabo]

Lagarith:

[poisondeathray]

Interesting, what version of lagarith are you using jagabo ? I'm using the latest and it doesn't list any restrictions

And a quick test shows 450x450 RGB lagarith works fine, decodes fine

Other formats e.g. ut video codec have mod2 restriction on YUY2/YV12, but none on RGB

[jagabo]

Interesting, what version of lagarith are you using jagabo ? I'm using the latest and it doesn't list any restrictions

And a quick test shows 450x450 RGB lagarith works fine, decodes fine

Other formats e.g. ut video codec have mod2 restriction on YUY2/YV12, but none on RGB

1.3.20. I haven't had any need to update. I just updated and checked. I got the same restriction. But a little digging turned up the fact that it depends on whether the input and compression mode are RGB or YUV.

[poisondeathray]

I would consider upgrading, it's significantly faster, ~20-30%

[jagabo]

Added to my last post.

[poisondeathray]

Added to my last post.

Yes I saw that. That's what I meant in my 1st post about lagarith in RGB mode should be able to render at any resolution