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On 7/23/2009 9:57 AM, <a class="moz-txt-link-abbreviated" href="mailto:xiphmont@xiph.org">xiphmont@xiph.org</a> wrote:
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cite="mid:806dafc20907230957v50c30e07g4e521756ccec86f@mail.gmail.com"
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<pre wrap=""><span class="moz-txt-citetags">> </span>It is said that Theora performs really well with low-resolution
<span class="moz-txt-citetags">> </span>content, but less with high-def content. How and why is Theora's
<span class="moz-txt-citetags">> </span>performance related to the size of the video? Is it an aspect of the
<span class="moz-txt-citetags">> </span>Theora spec (or of the VP3 spec), or is this caused by the
<span class="moz-txt-citetags">> </span>implementation?
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<pre wrap=""><!---->
The two biggest reasons Theora is said to be best for low res content
is becasue Theora's maximum motion vector size is relatively small
(+/-31 halfpel) and the minimum quantizer of DCT coefficients
relatively coarse compared to codecs designed for HD.</pre>
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To the untrained eye these seem like knobs that could be adjusted
pretty easily, but maybe with changes to the format. Would they need
changes to the Theora format (i.e. a Theora 2) to bridge the gap to HD
content?<br>
<br>
--Chris<br>
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