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<p class="MsoNormal"><span style="color:black">Hi,<o:p></o:p></span></p>
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<span style="color:black"> <o:p></o:p></span></p>
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<span style="color:black">I have a question regarding Ogg’s multiplexing process.<o:p></o:p></span></p>
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<span style="color:black"> <o:p></o:p></span></p>
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<span style="color:black">Let’s say we have two logical streams, S1 and S2, which need to be muxed together into one physical stream. On logical stream S1, we have a packet that’s too big and needs to be split into two pages, P1 and P2. On the other hand, logical
stream S2 also has a page Px that needs to go out. When these 2 logical streams are muxed together, on the resulting physical stream, is there any chance that Px from S2 can go in between P1 and P2? This will result in a physical stream that looks like … P1,
Px, P2 …<o:p></o:p></span></p>
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<span style="color:black"> <o:p></o:p></span></p>
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<span style="color:black">I found the following info from the Multiplexing section in this document:<span class="apple-converted-space"> </span><a href="https://www.xiph.org/ogg/doc/ogg-multiplex.html"><span style="color:#954F72">https://www.xiph.org/ogg/doc/ogg-multiplex.html</span></a>:<o:p></o:p></span></p>
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<i><span style="font-family:"-webkit-standard",serif;color:black">Ogg bitstreams multiplex multiple logical streams into a single physical stream at the page level. Each page contains an abstract time stamp (the Granule Position) that represents an absolute
time landmark within the stream. After the pages representing stream headers (all logical stream headers occur at the beginning of a physical bitstream section before any logical stream data), logical stream data pages are arranged in a physical bitstream
in strict non-decreasing order by chronological absolute time as specified by the granule position.</span></i><span style="font-family:"-webkit-standard",serif;color:black"><o:p></o:p></span></p>
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<i><span style="font-family:"-webkit-standard",serif;color:black">The only exception to arranging pages in strictly ascending time order by granule position is those pages that do not set the granule position value. This is a special case when exceptionally
large packets span multiple pages;</span></i><span style="font-family:"-webkit-standard",serif;color:black"><o:p></o:p></span></p>
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<span style="color:black"> </span><span style="color:black"><o:p></o:p></span></p>
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<span style="color:black">On my side, libogg is used to encode packets. The granule position is provided on a per packet bases. Based on the ogg documentation, I believe in the case I mentioned above, P1 from S1 will have a granule position T1, and P2 will
be following P1 and will not have a granule position set on the page. Let’s assume Px from S2 has a granule position Tx.<o:p></o:p></span></p>
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<span style="color:black"> <o:p></o:p></span></p>
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<span style="color:black">If Tx < T1, then I believe the page order on the physical stream will be Px, P1, P2.<o:p></o:p></span></p>
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<span style="color:black">If Tx > T1, then I’m suspecting that the pages will be like P1, P2, Px (and never P1, Px, P2).<o:p></o:p></span></p>
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<span style="color:black"> <o:p></o:p></span></p>
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<span style="color:black">Can someone help me understand if P1, Px, P2 can ever happen?<o:p></o:p></span></p>
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<span style="color:black"> <o:p></o:p></span></p>
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<span style="color:black">Thank you,<o:p></o:p></span></p>
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<span style="color:black">WD<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
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