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| 6 | <title>Ogg Vorbis Documentation</title>
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| 25 | #xiphlogo {
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| 29 | #content p {
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| 64 |
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| 65 | </head>
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| 66 |
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| 67 | <body>
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| 68 |
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| 69 | <div id="xiphlogo">
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| 70 | <a href="https://xiph.org/"><img src="fish_xiph_org.png" alt="Fish Logo and Xiph.Org"/></a>
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| 71 | </div>
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| 72 |
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| 73 | <h1>Programming with Xiph.Org <tt>libvorbis</tt></h1>
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| 74 |
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| 75 | <h2>Description</h2>
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| 76 |
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| 77 | <p>Libvorbis is the Xiph.Org Foundation's portable Ogg Vorbis CODEC
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| 78 | implemented as a programmatic library. Libvorbis provides primitives
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| 79 | to handle framing and manipulation of Ogg bitstreams (used by the
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| 80 | Vorbis for streaming), a full analysis (encoding) interface as well as
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| 81 | packet decoding and synthesis for playback.</p>
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| 82 |
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| 83 | <p>The libvorbis library does not provide any system interface; a
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| 84 | full-featured demonstration player included with the library
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| 85 | distribtion provides example code for a variety of system interfaces
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| 86 | as well as a working example of using libvorbis in production code.</p>
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| 87 |
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| 88 | <h2>Encoding Overview</h2>
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| 89 |
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| 90 | <h2>Decoding Overview</h2>
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| 91 |
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| 92 | <p>Decoding a bitstream with libvorbis follows roughly the following
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| 93 | steps:</p>
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| 94 |
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| 95 | <ol>
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| 96 | <li>Frame the incoming bitstream into pages</li>
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| 97 | <li>Sort the pages by logical bitstream and buffer then into logical streams</li>
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| 98 | <li>Decompose the logical streams into raw packets</li>
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| 99 | <li>Reconstruct segments of the original data from each packet</li>
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| 100 | <li>Glue the reconstructed segments back into a decoded stream</li>
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| 101 | </ol>
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| 102 |
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| 103 | <h3>Framing</h3>
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| 104 |
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| 105 | <p>An Ogg bitstream is logically arranged into pages, but to decode
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| 106 | the pages, we have to find them first. The raw bitstream is first fed
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| 107 | into an <tt>ogg_sync_state</tt> buffer using <tt>ogg_sync_buffer()</tt>
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| 108 | and <tt>ogg_sync_wrote()</tt>. After each block we submit to the sync
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| 109 | buffer, we should check to see if we can frame and extract a complete
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| 110 | page or pages using <tt>ogg_sync_pageout()</tt>. Extra pages are
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| 111 | buffered; allowing them to build up in the <tt>ogg_sync_state</tt>
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| 112 | buffer will eventually exhaust memory.</p>
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| 113 |
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| 114 | <p>The Ogg pages returned from <tt>ogg_sync_pageout</tt> need not be
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| 115 | decoded further to be used as landmarks in seeking; seeking can be
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| 116 | either a rough process of simply jumping to approximately intuited
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| 117 | portions of the bitstream, or it can be a precise bisection process
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| 118 | that captures pages and inspects data position. When seeking,
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| 119 | however, sequential multiplexing (chaining) must be accounted for;
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| 120 | beginning play in a new logical bitstream requires initializing a
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| 121 | synthesis engine with the headers from that bitstream. Vorbis
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| 122 | bitstreams do not make use of concurent multiplexing (grouping).</p>
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| 123 |
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| 124 | <h3>Sorting</h3>
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| 125 |
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| 126 | <p>The pages produced by <tt>ogg_sync_pageout</tt> are then sorted by
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| 127 | serial number to seperate logical bitstreams. Initialize logical
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| 128 | bitstream buffers (<tt>og_stream_state</tt>) using
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| 129 | <tt>ogg_stream_init()</tt>. Pages are submitted to the matching
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| 130 | logical bitstream buffer using <tt>ogg_stream_pagein</tt>; the serial
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| 131 | number of the page and the stream buffer must match, or the page will
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| 132 | be rejected. A page submitted out of sequence will simply be noted,
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| 133 | and in the course of outputting packets, the hole will be flagged
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| 134 | (<tt>ogg_sync_pageout</tt> and <tt>ogg_stream_packetout</tt> will
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| 135 | return a negative value at positions where they had to recapture the
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| 136 | stream).</p>
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| 137 |
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| 138 | <h3>Extracting packets</h3>
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| 139 |
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| 140 | <p>After submitting page[s] to a logical stream, read available packets
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| 141 | using <tt>ogg_stream_packetout</tt>.</p>
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| 142 |
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| 143 | <h3>Decoding packets</h3>
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| 144 |
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| 145 | <h3>Reassembling data segments</h3>
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| 146 |
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| 147 | <h2>Ogg Bitstream Manipulation Structures</h2>
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| 148 |
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| 149 | <p>Two of the Ogg bitstream data structures are intended to be
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| 150 | transparent to the developer; the fields should be used directly.</p>
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| 151 |
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| 152 | <h3>ogg_packet</h3>
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| 153 |
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| 154 | <pre>
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| 155 | typedef struct {
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| 156 | unsigned char *packet;
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| 157 | long bytes;
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| 158 | long b_o_s;
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| 159 | long e_o_s;
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| 160 |
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| 161 | size64 granulepos;
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| 162 |
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| 163 | } ogg_packet;
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| 164 | </pre>
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| 165 |
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| 166 | <dl>
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| 167 | <dt>packet:</dt>
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| 168 | <dd>a pointer to the byte data of the raw packet</dd>
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| 169 | <dt>bytes:</dt>
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| 170 | <dd>the size of the packet' raw data</dd>
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| 171 | <dt>b_o_s:</dt>
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| 172 | <dd>beginning of stream; nonzero if this is the first packet of
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| 173 | the logical bitstream</dd>
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| 174 | <dt>e_o_s:</dt>
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| 175 | <dd>end of stream; nonzero if this is the last packet of the
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| 176 | logical bitstream</dd>
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| 177 | <dt>granulepos:</dt>
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| 178 | <dd>the absolute position of this packet in the original
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| 179 | uncompressed data stream.</dd>
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| 180 | </dl>
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| 181 |
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| 182 | <h4>encoding notes</h4>
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| 183 |
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| 184 | <p>The encoder is responsible for setting all of
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| 185 | the fields of the packet to appropriate values before submission to
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| 186 | <tt>ogg_stream_packetin()</tt>; however, it is noted that the value in
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| 187 | <tt>b_o_s</tt> is ignored; the first page produced from a given
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| 188 | <tt>ogg_stream_state</tt> structure will be stamped as the initial
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| 189 | page. <tt>e_o_s</tt>, however, must be set; this is the means by
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| 190 | which the stream encoding primitives handle end of stream and cleanup.</p>
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| 191 |
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| 192 | <h4>decoding notes</h4>
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| 193 |
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| 194 | <p><tt>ogg_stream_packetout()</tt> sets the fields
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| 195 | to appropriate values. Note that granulepos will be >= 0 only in the
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| 196 | case that the given packet actually represents that position (ie, only
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| 197 | the last packet completed on any page will have a meaningful
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| 198 | <tt>granulepos</tt>). Intervening frames will see <tt>granulepos</tt> set
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| 199 | to -1.</p>
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| 200 |
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| 201 | <h3>ogg_page</h3>
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| 202 |
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| 203 | <pre>
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| 204 | typedef struct {
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| 205 | unsigned char *header;
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| 206 | long header_len;
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| 207 | unsigned char *body;
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| 208 | long body_len;
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| 209 | } ogg_page;
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| 210 | </pre>
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| 211 |
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| 212 | <dl>
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| 213 | <dt>header:</dt>
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| 214 | <dd>pointer to the page header data</dd>
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| 215 | <dt>header_len:</dt>
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| 216 | <dd>length of the page header in bytes</dd>
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| 217 | <dt>body:</dt>
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| 218 | <dd>pointer to the page body</dd>
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| 219 | <dt>body_len:</dt>
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| 220 | <dd>length of the page body</dd>
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| 221 | </dl>
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| 222 |
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| 223 | <p>Note that although the <tt>header</tt> and <tt>body</tt> pointers do
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| 224 | not necessarily point into a single contiguous page vector, the page
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| 225 | body must immediately follow the header in the bitstream.</p>
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| 226 |
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| 227 | <h2>Ogg Bitstream Manipulation Functions</h2>
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| 228 |
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| 229 | <h3>
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| 230 | int ogg_page_bos(ogg_page *og);
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| 231 | </h3>
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| 232 |
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| 233 | <p>Returns the 'beginning of stream' flag for the given Ogg page. The
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| 234 | beginning of stream flag is set on the initial page of a logical
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| 235 | bitstream.</p>
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| 236 |
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| 237 | <p>Zero indicates the flag is cleared (this is not the initial page of a
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| 238 | logical bitstream). Nonzero indicates the flag is set (this is the
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| 239 | initial page of a logical bitstream).</p>
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| 240 |
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| 241 | <h3>
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| 242 | int ogg_page_continued(ogg_page *og);
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| 243 | </h3>
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| 244 |
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| 245 | <p>Returns the 'packet continued' flag for the given Ogg page. The packet
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| 246 | continued flag indicates whether or not the body data of this page
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| 247 | begins with packet continued from a preceeding page.</p>
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| 248 |
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| 249 | <p>Zero (unset) indicates that the body data begins with a new packet.
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| 250 | Nonzero (set) indicates that the first packet data on the page is a
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| 251 | continuation from the preceeding page.</p>
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| 252 |
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| 253 | <h3>
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| 254 | int ogg_page_eos(ogg_page *og);
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| 255 | </h3>
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| 256 |
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| 257 | <p>Returns the 'end of stream' flag for a give Ogg page. The end of page
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| 258 | flag is set on the last (terminal) page of a logical bitstream.</p>
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| 259 |
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| 260 | <p>Zero (unset) indicates that this is not the last page of a logical
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| 261 | bitstream. Nonzero (set) indicates that this is the last page of a
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| 262 | logical bitstream and that no addiitonal pages belonging to this
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| 263 | bitstream may follow.</p>
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| 264 |
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| 265 | <h3>
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| 266 | size64 ogg_page_granulepos(ogg_page *og);
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| 267 | </h3>
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| 268 |
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| 269 | <p>Returns the position of this page as an absolute position within the
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| 270 | original uncompressed data. The position, as returned, is 'frames
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| 271 | encoded to date up to and including the last whole packet on this
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| 272 | page'. Partial packets begun on this page but continued to the
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| 273 | following page are not included. If no packet ends on this page, the
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| 274 | frame position value will be equal to the frame position value of the
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| 275 | preceeding page. If none of the original uncompressed data is yet
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| 276 | represented in the logical bitstream (for example, the first page of a
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| 277 | bitstream consists only of a header packet; this packet encodes only
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| 278 | metadata), the value shall be zero.</p>
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| 279 |
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| 280 | <p>The units of the framenumber are determined by media mapping. A
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| 281 | vorbis audio bitstream, for example, defines one frame to be the
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| 282 | channel values from a single sampling period (eg, a 16 bit stereo
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| 283 | bitstream consists of two samples of two bytes for a total of four
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| 284 | bytes, thus a frame would be four bytes). A video stream defines one
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| 285 | frame to be a single frame of video.</p>
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| 286 |
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| 287 | <h3>
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| 288 | int ogg_page_pageno(ogg_page *og);
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| 289 | </h3>
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| 290 |
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| 291 | <p>Returns the sequential page number of the given Ogg page. The first
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| 292 | page in a logical bitstream is numbered zero; following pages are
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| 293 | numbered in increasing monotonic order.</p>
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| 294 |
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| 295 | <h3>
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| 296 | int ogg_page_serialno(ogg_page *og);
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| 297 | </h3>
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| 298 |
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| 299 | <p>Returns the serial number of the given Ogg page. The serial number is
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| 300 | used as a handle to distinguish various logical bitstreams in a
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| 301 | physical Ogg bitstresm. Every logical bitstream within a
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| 302 | physical bitstream must use a unique (within the scope of the physical
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| 303 | bitstream) serial number, which is stamped on all bitstream pages.</p>
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| 304 |
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| 305 | <h3>
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| 306 | int ogg_page_version(ogg_page *og);
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| 307 | </h3>
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| 308 |
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| 309 | <p>Returns the revision of the Ogg bitstream structure of the given page.
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| 310 | Currently, the only permitted number is zero. Later revisions of the
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| 311 | bitstream spec will increment this version should any changes be
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| 312 | incompatable.</p>
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| 313 |
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| 314 | <h3>
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| 315 | int ogg_stream_clear(ogg_stream_state *os);
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| 316 | </h3>
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| 317 |
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| 318 | <p>Clears and deallocates the internal storage of the given Ogg stream.
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| 319 | After clearing, the stream structure is not initialized for use;
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| 320 | <tt>ogg_stream_init</tt> must be called to reinitialize for use.
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| 321 | Use <tt>ogg_stream_reset</tt> to reset the stream state
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| 322 | to a fresh, intiialized state.</p>
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| 323 |
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| 324 | <p><tt>ogg_stream_clear</tt> does not call <tt>free()</tt> on the pointer
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| 325 | <tt>os</tt>, allowing use of this call on stream structures in static
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| 326 | or automatic storage. <tt>ogg_stream_destroy</tt>is a complimentary
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| 327 | function that frees the pointer as well.</p>
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| 328 |
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| 329 | <p>Returns zero on success and non-zero on failure. This function always
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| 330 | succeeds.</p>
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| 331 |
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| 332 | <h3>
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| 333 | int ogg_stream_destroy(ogg_stream_state *os);
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| 334 | </h3>
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| 335 |
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| 336 | <p>Clears and deallocates the internal storage of the given Ogg stream,
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| 337 | then frees the storage associated with the pointer <tt>os</tt>.</p>
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| 338 |
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| 339 | <p><tt>ogg_stream_clear</tt> does not call <tt>free()</tt> on the pointer
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| 340 | <tt>os</tt>, allowing use of that call on stream structures in static
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| 341 | or automatic storage.</p>
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| 342 |
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| 343 | <p>Returns zero on success and non-zero on failure. This function always
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| 344 | succeeds.</p>
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| 345 |
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| 346 | <h3>
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| 347 | int ogg_stream_init(ogg_stream_state *os,int serialno);
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| 348 | </h3>
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| 349 |
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| 350 | <p>Initialize the storage associated with <tt>os</tt> for use as an Ogg
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| 351 | stream. This call is used to initialize a stream for both encode and
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| 352 | decode. The given serial number is the serial number that will be
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| 353 | stamped on pages of the produced bitstream (during encode), or used as
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| 354 | a check that pages match (during decode).</p>
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| 355 |
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| 356 | <p>Returns zero on success, nonzero on failure.</p>
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| 357 |
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| 358 | <h3>
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| 359 | int ogg_stream_packetin(ogg_stream_state *os, ogg_packet *op);
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| 360 | </h3>
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| 361 |
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| 362 | <p>Used during encoding to add the given raw packet to the given Ogg
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| 363 | bitstream. The contents of <tt>op</tt> are copied;
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| 364 | <tt>ogg_stream_packetin</tt> does not retain any pointers into
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| 365 | <tt>op</tt>'s storage. The encoding proccess buffers incoming packets
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| 366 | until enough packets have been assembled to form an entire page;
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| 367 | <tt>ogg_stream_pageout</tt> is used to read complete pages.</p>
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| 368 |
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| 369 | <p>Returns zero on success, nonzero on failure.</p>
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| 370 |
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| 371 | <h3>
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| 372 | int ogg_stream_packetout(ogg_stream_state *os,ogg_packet *op);
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| 373 | </h3>
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| 374 |
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| 375 | <p>Used during decoding to read raw packets from the given logical
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| 376 | bitstream. <tt>ogg_stream_packetout</tt> will only return complete
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| 377 | packets for which checksumming indicates no corruption. The size and
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| 378 | contents of the packet exactly match those given in the encoding
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| 379 | process. </p>
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| 380 |
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| 381 | <p>Returns zero if the next packet is not ready to be read (not buffered
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| 382 | or incomplete), positive if it returned a complete packet in
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| 383 | <tt>op</tt> and negative if there is a gap, extra bytes or corruption
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| 384 | at this position in the bitstream (essentially that the bitstream had
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| 385 | to be recaptured). A negative value is not necessarily an error. It
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| 386 | would be a common occurence when seeking, for example, which requires
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| 387 | recapture of the bitstream at the position decoding continued.</p>
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| 388 |
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| 389 | <p>If the return value is positive, <tt>ogg_stream_packetout</tt> placed
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| 390 | a packet in <tt>op</tt>. The data in <tt>op</tt> points to static
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| 391 | storage that is valid until the next call to
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| 392 | <tt>ogg_stream_pagein</tt>, <tt>ogg_stream_clear</tt>,
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| 393 | <tt>ogg_stream_reset</tt>, or <tt>ogg_stream_destroy</tt>. The
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| 394 | pointers are not invalidated by more calls to
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| 395 | <tt>ogg_stream_packetout</tt>.</p>
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| 396 |
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| 397 | <h3>
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| 398 | int ogg_stream_pagein(ogg_stream_state *os, ogg_page *og);
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| 399 | </h3>
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| 400 |
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| 401 | <p>Used during decoding to buffer the given complete, pre-verified page
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| 402 | for decoding into raw Ogg packets. The given page must be framed,
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| 403 | normally produced by <tt>ogg_sync_pageout</tt>, and from the logical
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| 404 | bitstream associated with <tt>os</tt> (the serial numbers must match).
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| 405 | The contents of the given page are copied; <tt>ogg_stream_pagein</tt>
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| 406 | retains no pointers into <tt>og</tt> storage.</p>
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| 407 |
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| 408 | <p>Returns zero on success and non-zero on failure.</p>
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| 409 |
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| 410 | <h3>
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| 411 | int ogg_stream_pageout(ogg_stream_state *os, ogg_page *og);
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| 412 | </h3>
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| 413 |
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| 414 | <p>Used during encode to read complete pages from the stream buffer. The
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| 415 | returned page is ready for sending out to the real world.</p>
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| 416 |
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| 417 | <p>Returns zero if there is no complete page ready for reading. Returns
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| 418 | nonzero when it has placed data for a complete page into
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| 419 | <tt>og</tt>. Note that the storage returned in og points into internal
|
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| 420 | storage; the pointers in <tt>og</tt> are valid until the next call to
|
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| 421 | <tt>ogg_stream_pageout</tt>, <tt>ogg_stream_packetin</tt>,
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| 422 | <tt>ogg_stream_reset</tt>, <tt>ogg_stream_clear</tt> or
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| 423 | <tt>ogg_stream_destroy</tt>.</p>
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| 424 |
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| 425 | <h3>
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| 426 | int ogg_stream_reset(ogg_stream_state *os);
|
|---|
| 427 | </h3>
|
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| 428 |
|
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| 429 | <p>Resets the given stream's state to that of a blank, unused stream;
|
|---|
| 430 | this may be used during encode or decode.</p>
|
|---|
| 431 |
|
|---|
| 432 | <p>Note that if used during encode, it does not alter the stream's serial
|
|---|
| 433 | number. In addition, the next page produced during encoding will be
|
|---|
| 434 | marked as the 'initial' page of the logical bitstream.</p>
|
|---|
| 435 |
|
|---|
| 436 | <p>When used during decode, this simply clears the data buffer of any
|
|---|
| 437 | pending pages. Beginning and end of stream cues are read from the
|
|---|
| 438 | bitstream and are unaffected by reset.</p>
|
|---|
| 439 |
|
|---|
| 440 | <p>Returns zero on success and non-zero on failure. This function always
|
|---|
| 441 | succeeds.</p>
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| 442 |
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| 443 | <h3>
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|---|
| 444 | char *ogg_sync_buffer(ogg_sync_state *oy, long size);
|
|---|
| 445 | </h3>
|
|---|
| 446 |
|
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| 447 | <p>This call is used to buffer a raw bitstream for framing and
|
|---|
| 448 | verification. <tt>ogg_sync_buffer</tt> handles stream capture and
|
|---|
| 449 | recapture, checksumming, and division into Ogg pages (as required by
|
|---|
| 450 | <tt>ogg_stream_pagein</tt>).</p>
|
|---|
| 451 |
|
|---|
| 452 | <p><tt>ogg_sync_buffer</tt> exposes a buffer area into which the decoder
|
|---|
| 453 | copies the next (up to) <tt>size</tt> bytes. We expose the buffer
|
|---|
| 454 | (rather than taking a buffer) in order to avoid an extra copy many
|
|---|
| 455 | uses; this way, for example, <tt>read()</tt> can transfer data
|
|---|
| 456 | directly into the stream buffer without first needing to place it in
|
|---|
| 457 | temporary storage.</p>
|
|---|
| 458 |
|
|---|
| 459 | <p>Returns a pointer into <tt>oy</tt>'s internal bitstream sync buffer;
|
|---|
| 460 | the remaining space in the sync buffer is at least <tt>size</tt>
|
|---|
| 461 | bytes. The decoder need not write all of <tt>size</tt> bytes;
|
|---|
| 462 | <tt>ogg_sync_wrote</tt> is used to inform the engine how many bytes
|
|---|
| 463 | were actually written. Use of <tt>ogg_sync_wrote</tt> after writing
|
|---|
| 464 | into the exposed buffer is mandantory.</p>
|
|---|
| 465 |
|
|---|
| 466 | <h3>
|
|---|
| 467 | int ogg_sync_clear(ogg_sync_state *oy);
|
|---|
| 468 | </h3>
|
|---|
| 469 |
|
|---|
| 470 | <p><tt>ogg_sync_clear</tt>
|
|---|
| 471 | clears and deallocates the internal storage of the given Ogg sync
|
|---|
| 472 | buffer. After clearing, the sync structure is not initialized for
|
|---|
| 473 | use; <tt>ogg_sync_init</tt> must be called to reinitialize for use.
|
|---|
| 474 | Use <tt>ogg_sync_reset</tt> to reset the sync state and buffer to a
|
|---|
| 475 | fresh, intiialized state.</p>
|
|---|
| 476 |
|
|---|
| 477 | <p><tt>ogg_sync_clear</tt> does not call <tt>free()</tt> on the pointer
|
|---|
| 478 | <tt>oy</tt>, allowing use of this call on sync structures in static
|
|---|
| 479 | or automatic storage. <tt>ogg_sync_destroy</tt>is a complimentary
|
|---|
| 480 | function that frees the pointer as well.</p>
|
|---|
| 481 |
|
|---|
| 482 | <p>Returns zero on success and non-zero on failure. This function always
|
|---|
| 483 | succeeds.</p>
|
|---|
| 484 |
|
|---|
| 485 | <h3>
|
|---|
| 486 | int ogg_sync_destroy(ogg_sync_state *oy);
|
|---|
| 487 | </h3>
|
|---|
| 488 |
|
|---|
| 489 | <p>Clears and deallocates the internal storage of the given Ogg sync
|
|---|
| 490 | buffer, then frees the storage associated with the pointer
|
|---|
| 491 | <tt>oy</tt>.</p>
|
|---|
| 492 |
|
|---|
| 493 | <p>An alternative function,<tt>ogg_sync_clear</tt>, does not call
|
|---|
| 494 | <tt>free()</tt> on the pointer <tt>oy</tt>, allowing use of that call on
|
|---|
| 495 | stream structures in static or automatic storage.</p>
|
|---|
| 496 |
|
|---|
| 497 | <p>Returns zero on success and non-zero on failure. This function always
|
|---|
| 498 | succeeds.</p>
|
|---|
| 499 |
|
|---|
| 500 | <h3>
|
|---|
| 501 | int ogg_sync_init(ogg_sync_state *oy);
|
|---|
| 502 | </h3>
|
|---|
| 503 |
|
|---|
| 504 | <p>Initializes the sync buffer <tt>oy</tt> for use.</p>
|
|---|
| 505 |
|
|---|
| 506 | <p>Returns zero on success and non-zero on failure. This function always
|
|---|
| 507 | succeeds.</p>
|
|---|
| 508 |
|
|---|
| 509 | <h3>
|
|---|
| 510 | int ogg_sync_pageout(ogg_sync_state *oy, ogg_page *og);
|
|---|
| 511 | </h3>
|
|---|
| 512 |
|
|---|
| 513 | <p>Reads complete, framed, verified Ogg pages from the sync buffer,
|
|---|
| 514 | placing the page data in <tt>og</tt>.</p>
|
|---|
| 515 |
|
|---|
| 516 | <p>Returns zero when there's no complete pages buffered for
|
|---|
| 517 | retrieval. Returns negative when a loss of sync or recapture occurred
|
|---|
| 518 | (this is not necessarily an error; recapture would be required after
|
|---|
| 519 | seeking, for example). Returns positive when a page is returned in
|
|---|
| 520 | <tt>og</tt>. Note that the data in <tt>og</tt> points into the sync
|
|---|
| 521 | buffer storage; the pointers are valid until the next call to
|
|---|
| 522 | <tt>ogg_sync_buffer</tt>, <tt>ogg_sync_clear</tt>,
|
|---|
| 523 | <tt>ogg_sync_destroy</tt> or <tt>ogg_sync_reset</tt>.</p>
|
|---|
| 524 |
|
|---|
| 525 | <h3>
|
|---|
| 526 | int ogg_sync_reset(ogg_sync_state *oy);
|
|---|
| 527 | </h3>
|
|---|
| 528 |
|
|---|
| 529 | <p><tt>ogg_sync_reset</tt> resets the sync state in <tt>oy</tt> to a
|
|---|
| 530 | clean, empty state. This is useful, for example, when seeking to a
|
|---|
| 531 | new location in a bitstream.</p>
|
|---|
| 532 |
|
|---|
| 533 | <p>Returns zero on success, nonzero on failure.</p>
|
|---|
| 534 |
|
|---|
| 535 | <h3>
|
|---|
| 536 | int ogg_sync_wrote(ogg_sync_state *oy, long bytes);
|
|---|
| 537 | </h3>
|
|---|
| 538 |
|
|---|
| 539 | <p>Used to inform the sync state as to how many bytes were actually
|
|---|
| 540 | written into the exposed sync buffer. It must be equal to or less
|
|---|
| 541 | than the size of the buffer requested.</p>
|
|---|
| 542 |
|
|---|
| 543 | <p>Returns zero on success and non-zero on failure; failure occurs only
|
|---|
| 544 | when the number of bytes written were larger than the buffer.</p>
|
|---|
| 545 |
|
|---|
| 546 | <div id="copyright">
|
|---|
| 547 | The Xiph Fish Logo is a
|
|---|
| 548 | trademark (™) of Xiph.Org.<br/>
|
|---|
| 549 |
|
|---|
| 550 | These pages © 1994 - 2005 Xiph.Org. All rights reserved.
|
|---|
| 551 | </div>
|
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| 552 |
|
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| 553 | </body>
|
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| 554 | </html>
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