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List:       xine-codec-devel
Subject:    Re: [codec-devel] Fwd: Sorenson Spark question
From:       Mike Melanson <melanson () pcisys ! net>
Date:       2004-01-10 23:37:44
Message-ID: Pine.LNX.4.44.0401101633090.182-100000 () x-wing ! tmmm ! home
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On Sat, 10 Jan 2004, Benjamin Larsson wrote:

> Sorenson Spark is an interframe codec. Sorenson Spark’s efficient
> interframe compression, among other features, distinguishes it from
> other compression technologies, requiring a much lower data rate than
> most other codecs to produce good-quality video. Many other codecs use
> intraframe compression; for example, JPEG is an intraframe codec.
>
> However, interframe codecs also use intraframes. The intraframes are
> used as the reference frames (keyframes) for the interframes. Sorenson
> Spark always begins with a keyframe. Each keyframe becomes the main
> reference frame for the following interframes. Whenever the next frame
> is significantly different from the previous frame, the codec compresses
> a new keyframe.

	Wow, this is some of the most inane marketing schlock I have ever
read, at least pertaining to multimedia technology...:) "Our revolutionary
codec technology uses 'interframes' to achieve greater compression than
our competitors..."

> uses the name other versions of Spark video codec. So I would assume
> that Sorenson just "sold" Macromedia an updated version of the codec
> they licensed to Apple. And that would mean that it is a modified
> version of H.263 (that's what svq3 is if IIRC). And I havn't seen an
> open source svq3 encoder so I would guess that there aren't any for Spark.

	SVQ3 is actually H.264-based. I know that Sorenson does work based
on all kinds of video codecs, including some that are based on H.263 and
ISO MPEG-4. And then SVQ1 was a vector quantizer.

	I remember Apple made a fuss some time ago when Sorenson licensed
some codec tech to Macromedia. Something about how Apple was supposed to
have exclusive use. The legal dispute was settled peacefully, if memory
serves. But I was left with the impression that the stuff Sorenson gave to
Macromedia is different than SVQ1 or SVQ3.

--
	-Mike Melanson



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