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<h1>Writing with OggzHungry callbacks</h1> </div>
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<p>You can add packets to the Oggz packet queue only when it is "hungry" by providing an OggzHungry callback.
<a href="#_details">More...</a></p>
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<p>You can add packets to the Oggz packet queue only when it is "hungry" by providing an OggzHungry callback. </p>
<p>An OggzHungry callback will:</p>
<ul>
<li>Create an <em>ogg_packet</em> structure</li>
<li>Add it to the packet queue with <a class="el" href="group__write__api.html#ga6ccaceb107db1fd2eae047dbdbaa5889" title="Add a packet to oggz's packet queue.">oggz_write_feed()</a></li>
</ul>
<p>Once you have set such a callback with <a class="el" href="group__write__api.html#gaf362c030bc7a7f57cb23f2b863a59389" title="Set a callback for Oggz to call when oggz is hungry .">oggz_write_set_hungry_callback()</a>, simply call <a class="el" href="group__write__api.html#ga3c97d94ea425d64546adf9c368b71904" title="Write n bytes from an OGGZ handle.">oggz_write()</a> or <a class="el" href="group__write__api.html#ga5606dff01964caec4582eb172fde0c1c" title="Output data from an OGGZ handle.">oggz_write_output()</a> repeatedly, and Oggz will call your callback to provide packets when it is hungry.</p>
<p>This process is illustrated in the following diagram:</p>
<div align="center">
<img src="hungry.png" alt="hungry.png"/>
</div>
<p>The following example code generates a stream of ten packets, each containing a single byte ('A', 'B', ... , 'J'):</p>
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<span class="preprocessor">#include <stdlib.h></span> <span class="comment">/* exit */</span>
<span class="preprocessor">#include "<a class="code" href="oggz_8h.html" title="The liboggz C API.">oggz/oggz.h</a>"</span>
<span class="keyword">static</span> <span class="keywordtype">long</span> serialno;
<span class="keyword">static</span> ogg_int64_t granulepos = 0;
<span class="keyword">static</span> ogg_int64_t packetno = 0;
<span class="keyword">static</span> <span class="keywordtype">int</span>
hungry (<a class="code" href="oggz_8h.html#a672d218df13da45a4b41d5366211bfee" title="An opaque handle to an Ogg file.">OGGZ</a> * oggz, <span class="keywordtype">int</span> empty, <span class="keywordtype">void</span> * user_data)
{
ogg_packet op;
<span class="keywordtype">unsigned</span> <span class="keywordtype">char</span> buf[1];
buf[0] = <span class="charliteral">'A'</span> + (int)packetno;
op.packet = buf;
op.bytes = 1;
op.granulepos = granulepos;
op.packetno = packetno;
<span class="keywordflow">if</span> (packetno == 0) op.b_o_s = 1;
<span class="keywordflow">else</span> op.b_o_s = 0;
<span class="keywordflow">if</span> (packetno == 9) op.e_o_s = 1;
<span class="keywordflow">else</span> op.e_o_s = 0;
<a class="code" href="group__write__api.html#ga6ccaceb107db1fd2eae047dbdbaa5889" title="Add a packet to oggz&#39;s packet queue.">oggz_write_feed</a> (oggz, &op, serialno, <a class="code" href="oggz__constants_8h.html#a6a09e7685c864a9116473b236c847237a42efb730f40edcdb0dfdb8a6294619c4" title="Flush after this packet.">OGGZ_FLUSH_AFTER</a>, NULL);
granulepos += 100;
packetno++;
<span class="keywordflow">return</span> 0;
}
<span class="keywordtype">int</span>
main (<span class="keywordtype">int</span> argc, <span class="keywordtype">char</span> * argv[])
{
<span class="keywordtype">char</span> * progname, * filename = NULL;
<a class="code" href="oggz_8h.html#a672d218df13da45a4b41d5366211bfee" title="An opaque handle to an Ogg file.">OGGZ</a> * oggz;
<span class="keywordtype">long</span> n;
progname = argv[0];
<span class="keywordflow">if</span> (argc > 1) filename = argv[1];
<span class="keywordflow">if</span> (filename) {
oggz = <a class="code" href="oggz_8h.html#a65197cdd03f755f7ebfabf2fdff4c7db" title="Open an Ogg file, creating an OGGZ handle for it.">oggz_open</a> (filename, <a class="code" href="oggz__constants_8h.html#a12afc3c052f6e84eff5a99ac9f1ccdd3a8819c3d01c84191dbf846b5e0a98d757" title="Write only.">OGGZ_WRITE</a>);
} <span class="keywordflow">else</span> {
oggz = <a class="code" href="oggz_8h.html#ac49e9de0bc4ef1d91b43b13605f98b19" title="Create an OGGZ handle associated with a stdio stream.">oggz_open_stdio</a> (stdout, <a class="code" href="oggz__constants_8h.html#a12afc3c052f6e84eff5a99ac9f1ccdd3a8819c3d01c84191dbf846b5e0a98d757" title="Write only.">OGGZ_WRITE</a>);
}
<span class="keywordflow">if</span> (oggz == NULL) {
fprintf (stderr, <span class="stringliteral">"%s: Error creating oggz\n"</span>, progname);
exit (1);
}
serialno = <a class="code" href="oggz_8h.html#aaf89877e3e89408387d422f487bcf094" title="Request a new serialno, as required for a new stream, ensuring the serialno is not yet used for any o...">oggz_serialno_new</a> (oggz);
<span class="keywordflow">if</span> (<a class="code" href="group__write__api.html#gaf362c030bc7a7f57cb23f2b863a59389" title="Set a callback for Oggz to call when oggz is hungry .">oggz_write_set_hungry_callback</a> (oggz, hungry, 1, NULL) == -1) {
fprintf (stderr, <span class="stringliteral">"%s: Error setting OggzHungry callback\n"</span>, progname);
exit (1);
}
<span class="keywordflow">while</span> ((n = <a class="code" href="group__write__api.html#ga3c97d94ea425d64546adf9c368b71904" title="Write n bytes from an OGGZ handle.">oggz_write</a> (oggz, 32)) > 0);
<a class="code" href="oggz_8h.html#aadcfc04b2930660710bbcbc93140b783" title="Close an OGGZ handle.">oggz_close</a> (oggz);
exit (0);
}
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