[MEncoder-users] Authoring for DVD - qpel?

[Ross Clement]

On 9/29/07, RC <cooleyr at gmail.com> wrote:
>
> With modern video codecs, you would have to go to great lengths to
> disable "motion compensation".  And BTW, motion _estimation_ (m.e.) is
> the more common term.
>
> So your answer is:  No.


Thank you.

With MPEG-2, I expect qpel will cause artifacts, as you DVD player
> doesn't know how to handle it.  That's assuming mencoder doesn't return
> an error and prevent you from even trying it.


It's not supported by the lavc mpeg2 codec. I tried it with mpeg4 but didn't
notice a big improvement. On my computer screen, not DVD, at least.

And more to the point, qpel doesn't enable motion estimation, it just
> enables an extra TYPE/METHOD (ie. quarter-pixel).


Yes, I was reading through the mencoder man page and there are clearly a
number of different types of estimation. It seems to me (please correct me
if I'm wrong) that trying the rate distortion comparison function for cmp
and subcmp might be worthwhile. If that works with the mpeg2 codec.

The option to change/disable motion compesation is actually 'vme', but
> it's most certainly enabled by default.


According to the man page, the default value for vme is "EPZS", whatever
that is. But "full" might be worth trying, though it's marked as slow. As
are most of the high quality options of course.

> Are there any more sophisticated experiments I should try (e.g.
> > varying other parameters related to motion compensation)?
>
> You might see some noticable gains by increasing the default diamond
> size...  See dia and predia.


I'll definitely try that.


> Besides that, you should just try the typical recomendations for
> improving video quality...


I may be looking at the wrong web sources. But I find that many pages on how
to "create high quality videos with mencoder" list options you might want to
use, without really going into what they mean. I personally believe that I
will benefit in the long run by going into individual options and groups of
options, and learning more about what they do. Though in the short term I
might REALLY ANNOY everyone on this list :)

Thanks muchly.