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<h1>encoding.c</h1><div class="fragment"><pre class="fragment"><span class="comment">/*</span>
<span class="comment"> This shows the steps necessary to encode a Kate stream.</span>
<span class="comment"> For clarity, error checking is omitted.</span>
<span class="comment"> */</span>
<span class="preprocessor">#include <stdio.h></span>
<span class="preprocessor">#include <string.h></span>
<span class="preprocessor">#include <ogg/ogg.h></span>
<span class="preprocessor">#include "common.h"</span>
<span class="comment">/* All the libkate API is available from the main kate header file: */</span>
<span class="preprocessor">#include <<a class="code" href="oggkate_8h.html">kate/oggkate.h</a>></span>
<span class="comment">/*</span>
<span class="comment"> We want to control when Ogg pages are output, as Kate is a discontinuous</span>
<span class="comment"> codec, so we don't know when the next event will happen, hence the need</span>
<span class="comment"> to create a page for every event.</span>
<span class="comment"> */</span>
<span class="keyword">static</span> <span class="keywordtype">void</span> flush_page(ogg_stream_state *os)
{
ogg_page og;
<span class="keywordflow">while</span> (1) {
<span class="keywordtype">int</span> ret=ogg_stream_flush(os,&og);
<span class="keywordflow">if</span> (ret==0) <span class="keywordflow">break</span>;
fwrite(og.header,1,og.header_len,stdout);
fwrite(og.body,1,og.body_len,stdout);
}
}
<span class="keywordtype">int</span> main()
{
<span class="comment">/* We need an Ogg stream to write to */</span>
ogg_stream_state os;
ogg_packet op;
<span class="comment">/*</span>
<span class="comment"> First, a kate_info structure needs to be created and setup for the stream to create.</span>
<span class="comment"> A kate_comment structure also has to be created.</span>
<span class="comment"> Information from both of these will get encoded into the stream headers.</span>
<span class="comment"> Last, we also need a kate_state structure, which will be initialized later.</span>
<span class="comment"> */</span>
<a name="_a0"></a><a class="code" href="structkate__info.html">kate_info</a> ki;
<a name="_a1"></a><a class="code" href="structkate__comment.html">kate_comment</a> kc;
<a name="_a2"></a><a class="code" href="structkate__state.html">kate_state</a> k;
<a name="a3"></a><a class="code" href="group__info.html#gab9031b2c167954bc7d754b30774f0241">kate_info_init</a>(&ki);
<a name="a4"></a><a class="code" href="group__comments.html#ga4f717746ed53e557e57bb1e2b40dbd84">kate_comment_init</a>(&kc);
<span class="comment">/*</span>
<span class="comment"> The most important part of the kate_info structure on encoding is the granule</span>
<span class="comment"> encoding information, which describes how granules and time are mapped.</span>
<span class="comment"> Here, we map one granule to one millisecond.</span>
<span class="comment"> */</span>
ki.<a name="a5"></a><a class="code" href="structkate__info.html#a1bf457732577344fa6d0f035d30d1e13">granule_shift</a>=32;
ki.<a name="a6"></a><a class="code" href="structkate__info.html#a7eb196702d96e5676b27838cadfd6acf">gps_numerator</a>=1000;
ki.<a name="a7"></a><a class="code" href="structkate__info.html#a00c2253966d5a22cc3e56f4f98dd4995">gps_denominator</a>=1;
<span class="comment">/* With that done, we can initialize libkate for encoding, and initialize libogg as well: */</span>
<a name="a8"></a><a class="code" href="group__encoding.html#ga0a7588d43b22fd5ef6e0a88ed7245210">kate_encode_init</a>(&k,&ki);
ogg_stream_init(&os,0x12345678);
<span class="comment">/* for the benefit of windows, which mangles data otherwise */</span>
set_binary_file(stdout);
<span class="comment">/*</span>
<span class="comment"> Before you can create events, headers need to be sent. Here, we'll just send</span>
<span class="comment"> the headers directly, but you will usually want to add regions, styles, etc to</span>
<span class="comment"> the headers before doing so:</span>
<span class="comment"> */</span>
<span class="keywordflow">while</span> (<a name="a9"></a><a class="code" href="oggkate_8h.html#ac9f5a00fc71e781a8c18bccb12c3f9f7">kate_ogg_encode_headers</a>(&k,&kc,&op)==0) {
ogg_stream_packetin(&os,&op);
ogg_packet_clear(&op);
}
flush_page(&os);
<span class="comment">/*</span>
<span class="comment"> Events can now be created, and we'll just create and send a single one here,</span>
<span class="comment"> starting at time 10 seconds, and stopping at time 15 seconds.</span>
<span class="comment"> */</span>
<span class="preprocessor">#define text "Hello, world!"</span>
<span class="preprocessor"></span> <a name="a10"></a><a class="code" href="oggkate_8h.html#aa66db5293b6c4afa2fbbf536d0d1e4dd">kate_ogg_encode_text</a>(&k,10.0,15.0,text,strlen(text)+1,&op);
ogg_stream_packetin(&os,&op);
ogg_packet_clear(&op);
flush_page(&os);
<span class="comment">/*</span>
<span class="comment"> When we're done, we can tell libkate so an "end of stream" packet will be generated,</span>
<span class="comment"> and clear the resources we've been using:</span>
<span class="comment"> */</span>
<a name="a11"></a><a class="code" href="oggkate_8h.html#a28a9b117b4051ed02c761f279d5c34ee">kate_ogg_encode_finish</a>(&k,-1,&op);
ogg_stream_packetin(&os,&op);
ogg_packet_clear(&op);
flush_page(&os);
ogg_stream_clear(&os);
<a name="a12"></a><a class="code" href="kate_8h.html#a8617b44c49f19262a9e03c0dcb45d971">kate_clear</a>(&k);
<a name="a13"></a><a class="code" href="group__info.html#gaa8ba295f7925e8926ed46510c28be60d">kate_info_clear</a>(&ki);
<a name="a14"></a><a class="code" href="group__comments.html#ga92e532be93459a5b1d6835b64c1129da">kate_comment_clear</a>(&kc);
<span class="comment">/*</span>
<span class="comment"> That's it, we now have created a full kate stream. You may now want to decode it,</span>
<span class="comment"> or multiplex it with a Theora video, etc.</span>
<span class="comment"> */</span>
<span class="keywordflow">return</span> 0;
}
</pre></div> </div>
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