diff options
| author | Monty <xiphmont@xiph.org> | 2010-03-28 10:15:49 +0000 |
|---|---|---|
| committer | Monty <xiphmont@xiph.org> | 2010-03-28 10:15:49 +0000 |
| commit | 94d93be0ef859dad298ac3a4672b671fa66340b8 (patch) | |
| tree | 0b9ae582e57e22d75865623c7c0bf36b7363b0a2 /doc | |
| parent | eb5d2391a7d3f236d5c7f7526fb38a5a5b062024 (diff) | |
| download | ogg-94d93be0ef859dad298ac3a4672b671fa66340b8.tar.gz | |
Add two new figures illustrating packets, pages, logical bitstreams and
physical bitstreams.
git-svn-id: http://svn.xiph.org/trunk/ogg@17095 0101bb08-14d6-0310-b084-bc0e0c8e3800
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/oggstream.html | 69 | ||||
| -rw-r--r-- | doc/packets.png | bin | 0 -> 19776 bytes | |||
| -rw-r--r-- | doc/pages.png | bin | 0 -> 45363 bytes |
3 files changed, 67 insertions, 2 deletions
diff --git a/doc/oggstream.html b/doc/oggstream.html index 485747d..87c91df 100644 --- a/doc/oggstream.html +++ b/doc/oggstream.html @@ -60,11 +60,44 @@ li { color: #888888; clear: both; } + +.caption { + color: #000000; + background-color: #aabbff; + margin: 1em; + margin-left: 2em; + margin-right: 2em; + padding: 1em; + padding-bottom: 0em; + overflow: hidden; +} + +.caption p { + clear: none; +} + +.caption img { + display: block; + margin: 0px; + margin-left: auto; + margin-right: auto; + margin-bottom: 1.5em; + background-color: #ffffff; + padding: 10px; +} + +#thepage { + margin-left: auto; + margin-right: auto; + width: 840px; +} + </style> </head> <body> +<div id="thepage"> <div id="xiphlogo"> <a href="http://www.xiph.org/"><img src="fish_xiph_org.png" alt="Fish Logo and Xiph.org"/></a> @@ -332,6 +365,20 @@ boundary information; strung together, the unframed packets form a <em>logical bitstream</em> of apparently random bytes with no internal landmarks. +<div class="caption"> + <img src="packets.png"> + + <p> Packets of raw codec data are not typically internally framed. + When they are strung together into a stream without any container to + provide framing, they lose their individual boundaries. Seek and + capture are not possible within an unframed stream, and for many + codecs with variable length payloads and/or early-packet termination + (such as Vorbis), it may become impossible to recover the original + frame boundaries even if the stream is scanned linearly from + beginning to end. + +</div> + <p>Logical bitstream packets are grouped and framed into Ogg pages along with a unique stream <em>serial number</em> to produce a <em>physical bitstream</em>. An <em>elementary stream</em> is a @@ -341,6 +388,23 @@ be split and encoded across one or more pages. The page decode mechanism is designed to recognize, verify and handle single pages at a time from the overall bitstream. +<div class="caption"> + <img src="pages.png"> + + <p> The primary purpose of a container is to provide framing for raw + packets, marking the packet boundaries so the exact packets can be + retrieved for decode later. The container also provides secondary + functions such as capture, timestamping, sequencing, stream + identification and so on. Not all of these functions are represented in the diagram. + + <p>In the Ogg container, pages do not necessarily contain + integer numbers of packets. Packets may span across page boundaries + or even multiple pages. This is necessary as pages have a maximum + possible size in order to provide capture guarantees, but packet + size is unbounded. +</div> + + <p><a href="framing.html">Ogg Bitstream Framing</a> specifies the page format of an Ogg bitstream, the packet coding process and elementary bitstreams in detail. @@ -455,8 +519,8 @@ scope of the physical bitstream.</p> consecutively. Such a physical bitstream obeys all the rules of both chained and multiplexed streams. Each link, when unchained, must stand on its own as a valid physical bitstream. Chained streams do -not mix; a new segment may not begin until all streams in the -preceding segment have terminated. </p> +not mix or interleave; a new segment may not begin until all streams +in the preceding segment have terminated. </p> <h2>Examples</h2> @@ -489,5 +553,6 @@ sequence order.</li> These pages © 1994 - 2010 Xiph.Org. All rights reserved. </div> +</div> </body> </html> diff --git a/doc/packets.png b/doc/packets.png Binary files differnew file mode 100644 index 0000000..917b6c1 --- /dev/null +++ b/doc/packets.png diff --git a/doc/pages.png b/doc/pages.png Binary files differnew file mode 100644 index 0000000..a6c748e --- /dev/null +++ b/doc/pages.png |
