Ah OK, thanks for clarifying. So a chroma value of 241 - 255 should just be treated as 240 then.<br><br><br>Regards,<br>Salsaman.<br clear="all"><br><a href="http://lives.sourceforge.net">http://lives.sourceforge.net</a><br>
<a href="https://www.ohloh.net/accounts/salsaman">https://www.ohloh.net/accounts/salsaman</a><br><br>
<br><br><div class="gmail_quote">On Wed, Apr 14, 2010 at 9:36 PM, Timothy B. Terriberry <span dir="ltr"><<a href="mailto:tterribe@email.unc.edu">tterribe@email.unc.edu</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div class="im">salsaman wrote:<br>
> Hi,<br>
> can somebody confirm whether theora uses clamped (16 - 235, 16 - 240) or<br>
> unclamped (0 - 255) YUV ?<br>
<br>
</div>The specification clearly states that the former is to be used (see<br>
Section 4.3). However, there is nothing internal to the codec that<br>
enforces this.<br>
<div class="im"><br>
> My tests are showing that Y is always in the range 16 - 235 but the U<br>
> and V channels occasionally go above 240.<br>
<br>
</div>The codec itself will not clamp things to these ranges, so the whole<br>
"lossy compression" thing can occasionally produce values slightly<br>
outside of them. This is normal.<br>
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</blockquote></div><br>