[theora] A comparison of VP3, and two MPEG-4 variants

Freun Laven FreunLaven at earthlink.net
Sun Mar 23 19:31:07 PST 2003

Mr. Miller

It's nice to see somebody of significance in here.

I'm certainly in no position to discuss the technical merits of
objective testing.  I simply do not know that much about the various
methods.  But I do have to take exception to your statement:

>I think you would be much better off relying on subjective
>measurements rather than PSNR.

Considering the incredible vaguness in what's considered "good enough",
any decent testing method is going to *have* to do some sort of
objective, reproducable measurments.  (Unless, of course, people are
going to be satisified with some group of 'experts' making declarations
of what is 'best'.)

Sure, there will always be some subjectiveness about what's best (which
will also depend on the specific situation), but you can't depend on

It's not really any different from the audio compression format wars.
You still have people arguing over Real vs. Microsoft vs. Ogg vs. Mp3 vs
Mp3pro etc.  All because it's totally subjective and everybody is using
different sound clips and codecs to base their opinions on.

With video it's even worse.  And for somebody like myself, who has
eyesight problems, what I would consider to be 'good' would probably be
laughed at by others, simply because I have trouble detecting the subtle

A purely subjective comparison is worthless.

Now, I certainly can't discuss the technical merits of the PSNR method
(or any other method), but since you seem to be very very familiar with
that method, perhaps you could help devise a tolerable way to
objectively measure the differences, along with subjective

When Theora does finally produce a 'shipping' product, people are going
to want to know how good it is, and I really don't think most are going
to be too satisfied with "its better than what you think" or some such.

They will probably want to know what its strengths and weaknesses are,
along with what compression levels give comparable visual quality
compared to other methods.

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