<div dir="ltr"><br><br><div class="gmail_quote">On Wed, Oct 15, 2008 at 8:14 AM, Anne van Kesteren <span dir="ltr"><<a href="mailto:annevk@opera.com">annevk@opera.com</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="Ih2E3d">On Wed, 15 Oct 2008 17:01:22 +0200, Sander van Zoest <<a href="mailto:sander@vanzoest.com" target="_blank">sander@vanzoest.com</a>> wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
I hate to say it, but if it was enough, I wouldn't be commenting here. It<br>
simply isn't accurate<br>
enough to store it as a float.<br>
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How is not accurate? In terms of precision it shouldn't really matter...</blockquote><div><br>We are talking video here. Precision is at its core. If you consider the majority of the broken<br>video out on the net today a good example of what you want more of then, I see no reason<br>
to accurately define PAR. I won't get into Frame Rates such as 59.94Hz, since that is off topic<br>here, but you can not accurately convert video on the fly if you do not have the exact ratio. All<br>this stems from the conversion from analog to digital and in the analog world we did a lot of funky<br>
tricks to make things work better on hardware of those days, but as our computers and electronics<br>in general get faster and faster, putting in inaccuracies can cause for some seriously ill side effects,<br>now and especially in the future. Because of the conversion from analog to digital there are a lot of funky areas where you end up with a PAR/SAR that would be rounded inaccurately if expressed as a float. 2 32-bit<br>
integers is what is used today, with the hope that that will get us into a fully square pixel world, by the time<br>the video quality gets good enough where we can no longer express PAR in 32-bit integers.<br><br>For some background on this see <<a href="http://lipas.uwasa.fi/~f76998/video/conversion/">http://lipas.uwasa.fi/~f76998/video/conversion/</a>>. I really do not want to<br>
add to the inaccuracies in the world, especially if we have a chance to do it right. <br><br>There are already many of these types of mistakes in things like Media RSS, I wouldn't know how to accurately express the frame rate of a 30M clip in the framerate attribute of the content element. For some of the madness that we are talking about here, see <<a href="http://groups.google.com/group/sci.engr.advanced-tv/msg/108815e3089c4d53?pli=1">http://groups.google.com/group/sci.engr.advanced-tv/msg/108815e3089c4d53?pli=1</a>>. <br>
<br>I am sort of of the camp, if you are going to even provide pixelratio as an attribute, then at least do it like every other container format out there, rather then expressing it a manner that limits its use and forces inaccuracies caused by rounding and human error (because they do not understand why you want a 10 digit float).<br>
<br>Take it for what it is worth.<br><br>-- Sander<br><br></div></div><br>
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