<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div><blockquote type="cite" class=""><div class=""><div class="WordSection1" style="page: WordSection1; font-family: Helvetica; font-size: 14px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><div style="margin: 0cm 0cm 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif;" class=""><span lang="EN-US" style="font-size: 11pt; font-family: Arial, sans-serif; color: rgb(31, 73, 125);" class="">I am afraid that the computation is a bit more complex in the ISO (see<span class="Apple-converted-space"> </span><a href="http://www.staroceans.org.s3-website-us-east-1.amazonaws.com/e-book/ISO-14496-10.pdf" style="color: purple; text-decoration: underline;" class="">http://www.staroceans.org.s3-website-us-east-1.amazonaws.com/e-book/ISO-14496-10.pdf</a>)<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif;" class=""><span lang="EN-US" style="font-size: 11pt; font-family: Arial, sans-serif; color: rgb(31, 73, 125);" class="">Divisor is not always 2, it could be 1, 2, 3,4 or 6.</span></div></div></div></blockquote><div><br class=""></div>Is this the “DeltaTfiDivisor” defined in the table on page 263 of that specification? I find that rather hard to follow, considering (for example) that the variable</div><div><span class="Apple-tab-span" style="white-space: pre;"> </span>∆<span style="font-size: 10pt; font-family: TimesNewRoman;" class="">t</span><span style="font-size: 6pt; font-family: TimesNewRoman; vertical-align: -2pt;" class="">fi,dpb</span><span style="font-size: 10pt; font-family: TimesNewRoman;" class="">( n )</span></div><div>seems to be defined in two separate ways, just sentences apart:</div><div><br class=""></div><div>
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<div class="column"><p class=""><span style="font-size: 10.000000pt; font-family: 'TimesNewRoman'" class=""><span class="Apple-tab-span" style="white-space:pre"> </span>When fixed_frame_rate_flag is equal to 1, for all n where n indicates the n-th picture in output order and picture n is not
the last picture in the bitstream in output order, the value of </span><span style="font-size: 10.000000pt; font-family: 'Symbol'" class="">∆</span><span style="font-size: 10.000000pt; font-family: 'TimesNewRoman'" class="">t</span><span style="font-size: 6.000000pt; font-family: 'TimesNewRoman'; vertical-align: -2.000000pt" class="">fi,dpb</span><span style="font-size: 10.000000pt; font-family: 'TimesNewRoman'" class="">( n ) is specified by </span><span style="font-size: 10pt; font-family: Symbol;" class="">∆</span><span style="font-size: 10pt; font-family: TimesNewRoman;" class="">t</span><span style="font-size: 6pt; font-family: TimesNewRoman; vertical-align: -2pt;" class="">fi,dpb</span><span style="font-size: 10pt; font-family: TimesNewRoman;" class="">( n ) = </span><span style="font-size: 10pt; font-family: Symbol;" class="">∆</span><span style="font-size: 10pt; font-family: TimesNewRoman;" class="">t</span><span style="font-size: 6pt; font-family: TimesNewRoman; vertical-align: -2pt;" class="">o,dpb</span><span style="font-size: 10pt; font-family: TimesNewRoman;" class="">( n ) </span><span style="font-size: 10pt; font-family: Symbol;" class="">÷ </span><span style="font-size: 10pt; font-family: TimesNewRoman;" class="">DeltaTfiDivisor</span></p><p class="">and</p><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span><span style="font-size: 10pt; font-family: TimesNewRoman;" class="">When fixed_frame_rate_flag is equal to 1, the value computed for </span><span style="font-size: 10pt; font-family: Symbol;" class="">∆</span><span style="font-size: 10pt; font-family: TimesNewRoman;" class="">t</span><span style="font-size: 6pt; font-family: TimesNewRoman; vertical-align: -2pt;" class="">fi,dpb</span><span style="font-size: 10pt; font-family: TimesNewRoman;" class="">( n ) shall be the same for all n > 0 and shall be
equal to num_units_in_tick </span><span style="font-size: 10pt; font-family: Symbol;" class="">÷ </span><span style="font-size: 10pt; font-family: TimesNewRoman;" class="">time_scale.</span></div><div class="">(with no mention of a divisor).</div><div class=""><span style="font-family: TimesNewRoman; font-size: 10pt;" class=""><br class=""></span></div><div class="">Ahh, the joys of dealing with a codec that’s designed by a committee :-)</div></div></div></div></div></div><br class=""><br class=""><div apple-content-edited="true" class="">
<span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; ">Ross Finlayson<br class="">Live Networks, Inc.<br class=""><a href="http://www.live555.com/" class="">http://www.live555.com/</a></span></span>
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