Re: [MEncoder-users] encoding technical question

De (from) (von) <jimht@shaw.ca> :

> 1) None of those dimensions are evenly divisible by 16 so your
> compression efficiency will suffer.

I know but It was just an example. The question is not about resolution.

> 2) Unless I am very much mistaken, CQ will not give you predictable
> file sizes, since it will use whatever bitrate is needed to provide
> the quality specified., so the basis of your question is flawed. In
> my experience, the only way to achieve a fixed final file size is to
> do two pass encoding specifying bitrate, not CQ or CR.

Sure but, read in doc :

resolution x CQ = (bitrate x 1000)/25 (if 25 fps)

In my example :

600x200x0.10=12000
450x150x0.177=11947.5

> 3) I am assuming that the underlying question is, "is it better to
> have more pixels at a lower quality, or fewer pixels at a higher
> quality?"

Sure (perhaps my question wasn't clear...)

> In reality the answer is bit more complex. Smaller images tend to
> have higher entropy (each pixel is more likely to be different from
> its neighbors) and therefore require slightly more bits per pixel to
> encode. Bitrate requirements do not scale linearly with image
> resolution.

> These are just my opinions, based on my experience, so take em with
> a grain of salt.

--
mxph

_______________________________________________
MEncoder-users mailing list
MEncoder-users@mplayerhq.hu
https://lists.mplayerhq.hu/mailman/listinfo/mencoder-users