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<!--Weave of 'Sound Durations' generated by Inweb-->
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<ul class="crumbs"><li><a href="../index.html">Home</a></li><li><a href="index.html">foundation</a></li><li><a href="index.html#6">Chapter 6: Media</a></li><li><b>Sound Durations</b></li></ul><p class="purpose">These utility routines look at the headers of AIFF, OGG Vorbis or MIDI files to find the durations, and verify that they are what they purport to be.</p>
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<ul class="toc"><li><a href="6-sd.html#SP1">§1. AIFF files</a></li><li><a href="6-sd.html#SP2">§2. OGG Vorbis files</a></li><li><a href="6-sd.html#SP3">§3. MIDI files</a></li></ul><hr class="tocbar">
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<p class="inwebparagraph"><a id="SP1"></a><b>§1. AIFF files. </b>The code in this section was once again originated by Toby Nelson. To
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explicate the following, see the specifications for AIFF and OGG headers.
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Durations are measured in centiseconds.
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</p>
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<pre class="display">
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<span class="reserved">int</span><span class="plain"> </span><span class="functiontext">SoundFiles::get_AIFF_duration<button class="popup" onclick="togglePopup('usagePopup465')">...<span class="popuptext" id="usagePopup465">Usage of <b>SoundFiles::get_AIFF_duration</b>:<br>none</span></button></span><span class="plain">(</span><span class="reserved">FILE</span><span class="plain"> *</span><span class="identifier">pFile</span><span class="plain">, </span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> *</span><span class="identifier">pDuration</span><span class="plain">,</span>
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<span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> *</span><span class="identifier">pBitsPerSecond</span><span class="plain">, </span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> *</span><span class="identifier">pChannels</span><span class="plain">, </span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> *</span><span class="identifier">pSampleRate</span><span class="plain">) {</span>
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<span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">sig</span><span class="plain">;</span>
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<span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">chunkID</span><span class="plain">;</span>
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<span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">chunkLength</span><span class="plain">;</span>
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<span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">numSampleFrames</span><span class="plain">;</span>
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<span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">sampleSize</span><span class="plain">;</span>
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<span class="reserved">if</span><span class="plain"> (!</span><span class="functiontext"><a href="6-bf.html#SP1">BinaryFiles::read_int32</a></span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, &</span><span class="identifier">sig</span><span class="plain">)) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">sig</span><span class="plain"> != </span><span class="constant">0x464F524D</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">; </span><span class="comment"> <code class="display"><span class="extract">"FORM"</span></code> indicating an IFF file</span>
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<span class="reserved">if</span><span class="plain"> (!</span><span class="functiontext"><a href="6-bf.html#SP1">BinaryFiles::read_int32</a></span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, &</span><span class="identifier">sig</span><span class="plain">)) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
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<span class="reserved">if</span><span class="plain"> (!</span><span class="functiontext"><a href="6-bf.html#SP1">BinaryFiles::read_int32</a></span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, &</span><span class="identifier">sig</span><span class="plain">)) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">sig</span><span class="plain"> != </span><span class="constant">0x41494646</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">; </span><span class="comment"> <code class="display"><span class="extract">"AIFF"</span></code> indicating an AIFF file</span>
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<span class="comment"> Read chunks, skipping over those we are not interested in</span>
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<span class="reserved">while</span><span class="plain"> (</span><span class="constant">TRUE</span><span class="plain">) {</span>
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<span class="reserved">if</span><span class="plain"> (!</span><span class="functiontext"><a href="6-bf.html#SP1">BinaryFiles::read_int32</a></span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, &</span><span class="identifier">chunkID</span><span class="plain">)) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
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<span class="reserved">if</span><span class="plain"> (!</span><span class="functiontext"><a href="6-bf.html#SP1">BinaryFiles::read_int32</a></span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, &</span><span class="identifier">chunkLength</span><span class="plain">)) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">chunkID</span><span class="plain"> == </span><span class="constant">0x434F4D4D</span><span class="plain">) { </span><span class="comment"> <code class="display"><span class="extract">"COMM"</span></code> indicates common AIFF data</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">chunkLength</span><span class="plain"> < </span><span class="constant">18</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">; </span><span class="comment"> Check we have enough data to read</span>
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<span class="reserved">if</span><span class="plain"> (!</span><span class="functiontext"><a href="6-bf.html#SP1">BinaryFiles::read_int16</a></span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, </span><span class="identifier">pChannels</span><span class="plain">)) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
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<span class="reserved">if</span><span class="plain"> (!</span><span class="functiontext"><a href="6-bf.html#SP1">BinaryFiles::read_int32</a></span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, &</span><span class="identifier">numSampleFrames</span><span class="plain">)) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
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<span class="reserved">if</span><span class="plain"> (!</span><span class="functiontext"><a href="6-bf.html#SP1">BinaryFiles::read_int16</a></span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, &</span><span class="identifier">sampleSize</span><span class="plain">)) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
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<span class="reserved">if</span><span class="plain"> (!</span><span class="functiontext"><a href="6-bf.html#SP5">BinaryFiles::read_float80</a></span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, </span><span class="identifier">pSampleRate</span><span class="plain">)) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
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<span class="reserved">if</span><span class="plain"> (*</span><span class="identifier">pSampleRate</span><span class="plain"> == </span><span class="constant">0</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">; </span><span class="comment"> Sanity check to avoid a divide by zero</span>
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<span class="comment"> Result is in centiseconds</span>
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<span class="plain">*</span><span class="identifier">pDuration</span><span class="plain"> = (</span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain">) (((</span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">long</span><span class="plain"> </span><span class="reserved">long</span><span class="plain">) </span><span class="identifier">numSampleFrames</span><span class="plain"> * </span><span class="constant">100</span><span class="plain">) / *</span><span class="identifier">pSampleRate</span><span class="plain">);</span>
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<span class="plain">*</span><span class="identifier">pBitsPerSecond</span><span class="plain"> = *</span><span class="identifier">pSampleRate</span><span class="plain"> * *</span><span class="identifier">pChannels</span><span class="plain"> * </span><span class="identifier">sampleSize</span><span class="plain">;</span>
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<span class="reserved">break</span><span class="plain">;</span>
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<span class="plain">} </span><span class="reserved">else</span><span class="plain"> {</span>
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<span class="comment"> Skip unwanted chunk</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">fseek</span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, (</span><span class="reserved">long</span><span class="plain">) </span><span class="identifier">chunkLength</span><span class="plain">, </span><span class="identifier">SEEK_CUR</span><span class="plain">) != </span><span class="constant">0</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
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<span class="plain">}</span>
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<span class="plain">}</span>
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<span class="reserved">return</span><span class="plain"> </span><span class="constant">TRUE</span><span class="plain">;</span>
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<span class="plain">}</span>
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</pre>
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<p class="inwebparagraph"></p>
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<p class="inwebparagraph"><a id="SP2"></a><b>§2. OGG Vorbis files. </b></p>
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<pre class="display">
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<span class="reserved">int</span><span class="plain"> </span><span class="functiontext">SoundFiles::get_OggVorbis_duration<button class="popup" onclick="togglePopup('usagePopup466')">...<span class="popuptext" id="usagePopup466">Usage of <b>SoundFiles::get_OggVorbis_duration</b>:<br>none</span></button></span><span class="plain">(</span><span class="reserved">FILE</span><span class="plain"> *</span><span class="identifier">pFile</span><span class="plain">, </span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> *</span><span class="identifier">pDuration</span><span class="plain">,</span>
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<span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> *</span><span class="identifier">pBitsPerSecond</span><span class="plain">, </span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> *</span><span class="identifier">pChannels</span><span class="plain">, </span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> *</span><span class="identifier">pSampleRate</span><span class="plain">) {</span>
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<span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">sig</span><span class="plain">;</span>
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<span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">version</span><span class="plain">;</span>
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<span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">numSegments</span><span class="plain">;</span>
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<span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">packetType</span><span class="plain">;</span>
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<span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">vorbisSig1</span><span class="plain">;</span>
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<span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">vorbisSig2</span><span class="plain">;</span>
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<span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">seekPos</span><span class="plain">;</span>
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<span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">fileLength</span><span class="plain">, </span><span class="identifier">bytesToRead</span><span class="plain">, </span><span class="identifier">lastSig</span><span class="plain">, </span><span class="identifier">index</span><span class="plain">;</span>
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<span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">long</span><span class="plain"> </span><span class="reserved">long</span><span class="plain"> </span><span class="identifier">granulePosition</span><span class="plain">;</span>
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<span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">char</span><span class="plain"> </span><span class="identifier">buffer</span><span class="plain">[256];</span>
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<span class="reserved">if</span><span class="plain"> (!</span><span class="functiontext"><a href="6-bf.html#SP1">BinaryFiles::read_int32</a></span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, &</span><span class="identifier">sig</span><span class="plain">)) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">sig</span><span class="plain"> != </span><span class="constant">0x4F676753</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">; </span><span class="comment"> <code class="display"><span class="extract">"OggS"</span></code> indicating an OGG file</span>
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<span class="comment"> Check OGG version is zero</span>
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<span class="reserved">if</span><span class="plain"> (!</span><span class="functiontext"><a href="6-bf.html#SP1">BinaryFiles::read_int8</a></span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, &</span><span class="identifier">version</span><span class="plain">)) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">version</span><span class="plain"> != </span><span class="constant">0</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
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<span class="comment"> Skip header type, granule position, serial number, page sequence and CRC</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">fseek</span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, </span><span class="constant">21</span><span class="plain">, </span><span class="identifier">SEEK_CUR</span><span class="plain">) != </span><span class="constant">0</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
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<span class="comment"> Read number of page segments</span>
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<span class="reserved">if</span><span class="plain"> (!</span><span class="functiontext"><a href="6-bf.html#SP1">BinaryFiles::read_int8</a></span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, &</span><span class="identifier">numSegments</span><span class="plain">)) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
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<span class="comment"> Skip segment table</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">fseek</span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, (</span><span class="reserved">long</span><span class="plain">) </span><span class="identifier">numSegments</span><span class="plain">, </span><span class="identifier">SEEK_CUR</span><span class="plain">) != </span><span class="constant">0</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
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<span class="comment"> Vorbis Identification header</span>
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<span class="reserved">if</span><span class="plain"> (!</span><span class="functiontext"><a href="6-bf.html#SP1">BinaryFiles::read_int8</a></span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, &</span><span class="identifier">packetType</span><span class="plain">)) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">packetType</span><span class="plain"> != </span><span class="constant">1</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
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<span class="reserved">if</span><span class="plain"> (!</span><span class="functiontext"><a href="6-bf.html#SP1">BinaryFiles::read_int32</a></span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, &</span><span class="identifier">vorbisSig1</span><span class="plain">)) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">vorbisSig1</span><span class="plain"> != </span><span class="constant">0x766F7262</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">; </span><span class="comment"> <code class="display"><span class="extract">"VORB"</span></code></span>
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<span class="reserved">if</span><span class="plain"> (!</span><span class="functiontext"><a href="6-bf.html#SP1">BinaryFiles::read_int16</a></span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, &</span><span class="identifier">vorbisSig2</span><span class="plain">)) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">vorbisSig2</span><span class="plain"> != </span><span class="constant">0x6973</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">; </span><span class="comment"> <code class="display"><span class="extract">"IS"</span></code></span>
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<span class="comment"> Check Vorbis version is zero</span>
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<span class="reserved">if</span><span class="plain"> (!</span><span class="functiontext"><a href="6-bf.html#SP1">BinaryFiles::read_int32</a></span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, &</span><span class="identifier">version</span><span class="plain">)) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">version</span><span class="plain"> != </span><span class="constant">0</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
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<span class="comment"> Read number of channels</span>
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<span class="reserved">if</span><span class="plain"> (!</span><span class="functiontext"><a href="6-bf.html#SP1">BinaryFiles::read_int8</a></span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, </span><span class="identifier">pChannels</span><span class="plain">)) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
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<span class="comment"> Read sample rate</span>
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<span class="reserved">if</span><span class="plain"> (!</span><span class="functiontext"><a href="6-bf.html#SP1">BinaryFiles::read_int32</a></span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, </span><span class="identifier">pSampleRate</span><span class="plain">)) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
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<span class="functiontext"><a href="6-bf.html#SP3">BinaryFiles::swap_bytes32</a></span><span class="plain">(</span><span class="identifier">pSampleRate</span><span class="plain">); </span><span class="comment"> Ogg Vorbis uses LSB first</span>
|
|
|
|
<span class="comment"> Skip bitrate maximum</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">fseek</span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, </span><span class="constant">4</span><span class="plain">, </span><span class="identifier">SEEK_CUR</span><span class="plain">) != </span><span class="constant">0</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
|
|
|
|
<span class="comment"> Read Nominal Bitrate</span>
|
|
<span class="reserved">if</span><span class="plain"> (!</span><span class="functiontext"><a href="6-bf.html#SP1">BinaryFiles::read_int32</a></span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, </span><span class="identifier">pBitsPerSecond</span><span class="plain">)) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
|
|
<span class="functiontext"><a href="6-bf.html#SP3">BinaryFiles::swap_bytes32</a></span><span class="plain">(</span><span class="identifier">pBitsPerSecond</span><span class="plain">); </span><span class="comment"> Ogg Vorbis uses LSB first</span>
|
|
|
|
<span class="comment"> Encoders can be unhelpful and give no bitrate in the header</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">pBitsPerSecond</span><span class="plain"> == </span><span class="constant">0</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
|
|
|
|
<span class="comment"> Search for the final Ogg page (near the end of the file) to read duration,</span>
|
|
<span class="comment"> i.e., read the last 4K of the file and look for the final <code class="display"><span class="extract">"OggS"</span></code> sig</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">fseek</span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, </span><span class="constant">0</span><span class="plain">, </span><span class="identifier">SEEK_END</span><span class="plain">) != </span><span class="constant">0</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
|
|
<span class="identifier">fileLength</span><span class="plain"> = (</span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain">) </span><span class="identifier">ftell</span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">);</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">fileLength</span><span class="plain"> < </span><span class="constant">4096</span><span class="plain">) </span><span class="identifier">seekPos</span><span class="plain"> = </span><span class="constant">0</span><span class="plain">;</span>
|
|
<span class="reserved">else</span><span class="plain"> </span><span class="identifier">seekPos</span><span class="plain"> = </span><span class="identifier">fileLength</span><span class="plain"> - </span><span class="constant">4096</span><span class="plain">;</span>
|
|
|
|
<span class="identifier">lastSig</span><span class="plain"> = </span><span class="constant">0xFFFFFFFF</span><span class="plain">;</span>
|
|
<span class="reserved">while</span><span class="plain"> (</span><span class="identifier">seekPos</span><span class="plain"> < </span><span class="identifier">fileLength</span><span class="plain">) {</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">fseek</span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, (</span><span class="reserved">long</span><span class="plain">) </span><span class="identifier">seekPos</span><span class="plain">, </span><span class="identifier">SEEK_SET</span><span class="plain">) != </span><span class="constant">0</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
|
|
<span class="identifier">bytesToRead</span><span class="plain"> = </span><span class="identifier">fileLength</span><span class="plain"> - </span><span class="identifier">seekPos</span><span class="plain">;</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">bytesToRead</span><span class="plain"> > </span><span class="constant">256</span><span class="plain">) </span><span class="identifier">bytesToRead</span><span class="plain"> = </span><span class="constant">256</span><span class="plain">;</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">fread</span><span class="plain">(</span><span class="identifier">buffer</span><span class="plain">, </span><span class="constant">1</span><span class="plain">, </span><span class="identifier">bytesToRead</span><span class="plain">, </span><span class="identifier">pFile</span><span class="plain">) != </span><span class="identifier">bytesToRead</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
|
|
|
|
<span class="reserved">for</span><span class="plain">(</span><span class="identifier">index</span><span class="plain"> = </span><span class="constant">0</span><span class="plain">; </span><span class="identifier">index</span><span class="plain"> < </span><span class="identifier">bytesToRead</span><span class="plain">; </span><span class="identifier">index</span><span class="plain">++) {</span>
|
|
<span class="reserved">if</span><span class="plain"> ((</span><span class="identifier">buffer</span><span class="plain">[</span><span class="identifier">index</span><span class="plain">] == </span><span class="constant">0x4F</span><span class="plain">) &&</span>
|
|
<span class="plain">(</span><span class="identifier">buffer</span><span class="plain">[</span><span class="identifier">index</span><span class="plain"> + </span><span class="constant">1</span><span class="plain">] == </span><span class="constant">0x67</span><span class="plain">) &&</span>
|
|
<span class="plain">(</span><span class="identifier">buffer</span><span class="plain">[</span><span class="identifier">index</span><span class="plain"> + </span><span class="constant">2</span><span class="plain">] == </span><span class="constant">0x67</span><span class="plain">) &&</span>
|
|
<span class="plain">(</span><span class="identifier">buffer</span><span class="plain">[</span><span class="identifier">index</span><span class="plain"> + </span><span class="constant">3</span><span class="plain">] == </span><span class="constant">0x53</span><span class="plain">)) {</span>
|
|
<span class="identifier">lastSig</span><span class="plain"> = </span><span class="identifier">seekPos</span><span class="plain"> + </span><span class="identifier">index</span><span class="plain">;</span>
|
|
<span class="plain">}</span>
|
|
<span class="plain">}</span>
|
|
|
|
<span class="comment"> Next place to read from is 256 bytes further on, but to catch</span>
|
|
<span class="comment"> sigs that span between these blocks, read the last four bytes again</span>
|
|
<span class="identifier">seekPos</span><span class="plain"> += </span><span class="constant">256</span><span class="plain"> - </span><span class="constant">4</span><span class="plain">;</span>
|
|
<span class="plain">}</span>
|
|
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">lastSig</span><span class="plain"> == </span><span class="constant">0xFFFFFFFF</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
|
|
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">fseek</span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, (</span><span class="reserved">long</span><span class="plain">) </span><span class="identifier">lastSig</span><span class="plain">, </span><span class="identifier">SEEK_SET</span><span class="plain">) != </span><span class="constant">0</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
|
|
<span class="reserved">if</span><span class="plain"> (!</span><span class="functiontext"><a href="6-bf.html#SP1">BinaryFiles::read_int32</a></span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, &</span><span class="identifier">sig</span><span class="plain">)) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">sig</span><span class="plain"> != </span><span class="constant">0x4F676753</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">; </span><span class="comment"> <code class="display"><span class="extract">"OggS"</span></code> indicating an OGG file</span>
|
|
|
|
<span class="comment"> Check OGG version is zero</span>
|
|
<span class="reserved">if</span><span class="plain"> (!</span><span class="functiontext"><a href="6-bf.html#SP1">BinaryFiles::read_int8</a></span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, &</span><span class="identifier">version</span><span class="plain">)) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">version</span><span class="plain"> != </span><span class="constant">0</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
|
|
|
|
<span class="comment"> Skip header Type</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">fseek</span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, </span><span class="constant">1</span><span class="plain">, </span><span class="identifier">SEEK_CUR</span><span class="plain">) != </span><span class="constant">0</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
|
|
|
|
<span class="reserved">if</span><span class="plain"> (!</span><span class="functiontext"><a href="6-bf.html#SP1">BinaryFiles::read_int64</a></span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, &</span><span class="identifier">granulePosition</span><span class="plain">)) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
|
|
<span class="functiontext"><a href="6-bf.html#SP3">BinaryFiles::swap_bytes64</a></span><span class="plain">(&</span><span class="identifier">granulePosition</span><span class="plain">);</span>
|
|
|
|
<span class="plain">*</span><span class="identifier">pDuration</span><span class="plain"> = (</span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain">) ((</span><span class="identifier">granulePosition</span><span class="plain"> * </span><span class="constant">100</span><span class="plain">) /</span>
|
|
<span class="plain">(</span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">long</span><span class="plain"> </span><span class="reserved">long</span><span class="plain">) *</span><span class="identifier">pSampleRate</span><span class="plain">);</span>
|
|
|
|
<span class="reserved">return</span><span class="plain"> </span><span class="constant">TRUE</span><span class="plain">;</span>
|
|
<span class="plain">}</span>
|
|
</pre>
|
|
|
|
<p class="inwebparagraph"></p>
|
|
|
|
<p class="inwebparagraph"><a id="SP3"></a><b>§3. MIDI files. </b>At one time it was proposed that Inform 7 should allow a third sound file
|
|
format: MIDI. This provoked considerable debate in July 2007 and enough
|
|
doubts were raised that the implementation below was never in fact
|
|
officially used. It is preserved here in case we ever revive the issue.
|
|
</p>
|
|
|
|
<p class="inwebparagraph">Inform is not really able to decide this for itself, in any case, since
|
|
it can only usefully provide sound files which the virtual machines it
|
|
compiles for will allow. At present, the Glulx virtual machine does not
|
|
officially support MIDI, which makes the question moot.
|
|
</p>
|
|
|
|
<pre class="display">
|
|
<span class="reserved">int</span><span class="plain"> </span><span class="functiontext">SoundFiles::get_MIDI_information<button class="popup" onclick="togglePopup('usagePopup467')">...<span class="popuptext" id="usagePopup467">Usage of <b>SoundFiles::get_MIDI_information</b>:<br>none</span></button></span><span class="plain">(</span><span class="reserved">FILE</span><span class="plain"> *</span><span class="identifier">pFile</span><span class="plain">, </span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> *</span><span class="identifier">pType</span><span class="plain">,</span>
|
|
<span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> *</span><span class="identifier">pNumTracks</span><span class="plain">) {</span>
|
|
<span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">sig</span><span class="plain">;</span>
|
|
<span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">length</span><span class="plain">;</span>
|
|
<span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">pulses</span><span class="plain">;</span>
|
|
<span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">frames_per_second</span><span class="plain">;</span>
|
|
<span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">subframes_per_frame</span><span class="plain">;</span>
|
|
<span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">clocks_per_second</span><span class="plain">;</span>
|
|
<span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">start_of_chunk_data</span><span class="plain">;</span>
|
|
<span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">status</span><span class="plain">;</span>
|
|
<span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">clocks</span><span class="plain">;</span>
|
|
<span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">sysex_length</span><span class="plain">;</span>
|
|
<span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">non_midi_event_length</span><span class="plain">;</span>
|
|
<span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">start_of_non_midi_data</span><span class="plain">;</span>
|
|
<span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">non_midi_event</span><span class="plain">;</span>
|
|
|
|
<span class="reserved">if</span><span class="plain"> (!</span><span class="functiontext"><a href="6-bf.html#SP1">BinaryFiles::read_int32</a></span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, &</span><span class="identifier">sig</span><span class="plain">)) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
|
|
|
|
<span class="comment"> <code class="display"><span class="extract">"RIFF"</span></code> indicating a RIFF file</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">sig</span><span class="plain"> == </span><span class="constant">0x52494646</span><span class="plain">) {</span>
|
|
<span class="comment"> Skip the filesize and typeID</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">fseek</span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, </span><span class="constant">8</span><span class="plain">, </span><span class="identifier">SEEK_CUR</span><span class="plain">) != </span><span class="constant">0</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
|
|
|
|
<span class="comment"> now read the real MIDI sig</span>
|
|
<span class="reserved">if</span><span class="plain"> (!</span><span class="functiontext"><a href="6-bf.html#SP1">BinaryFiles::read_int32</a></span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, &</span><span class="identifier">sig</span><span class="plain">)) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
|
|
<span class="plain">}</span>
|
|
|
|
<span class="comment"> <code class="display"><span class="extract">"MThd"</span></code> indicating a MIDI file</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">sig</span><span class="plain"> != </span><span class="constant">0x4D546864</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
|
|
|
|
<span class="comment"> Read length of chunk</span>
|
|
<span class="reserved">if</span><span class="plain"> (!</span><span class="functiontext"><a href="6-bf.html#SP1">BinaryFiles::read_int32</a></span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, &</span><span class="identifier">length</span><span class="plain">)) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
|
|
|
|
<span class="comment"> Make sure we have enough data to read</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">length</span><span class="plain"> < </span><span class="constant">6</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
|
|
|
|
<span class="comment"> Read the MIDI type: 0,1 or 2</span>
|
|
<span class="comment"> 0 means one track containing up to 16 channels to make a single tune</span>
|
|
<span class="comment"> 1 means one or more tracks, commonly each with a single channel, making up a single tune</span>
|
|
<span class="comment"> 2 means one or more tracks, where each is a separate tune in it's own right</span>
|
|
<span class="reserved">if</span><span class="plain"> (!</span><span class="functiontext"><a href="6-bf.html#SP1">BinaryFiles::read_int16</a></span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, </span><span class="identifier">pType</span><span class="plain">)) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
|
|
|
|
<span class="comment"> Read the number of tracks</span>
|
|
<span class="reserved">if</span><span class="plain"> (!</span><span class="functiontext"><a href="6-bf.html#SP1">BinaryFiles::read_int16</a></span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, </span><span class="identifier">pNumTracks</span><span class="plain">)) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
|
|
|
|
<span class="comment"> Read "Pulses Per Quarter Note" (PPQN)</span>
|
|
<span class="reserved">if</span><span class="plain"> (!</span><span class="functiontext"><a href="6-bf.html#SP1">BinaryFiles::read_int16</a></span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, &</span><span class="identifier">pulses</span><span class="plain">)) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
|
|
|
|
<span class="comment"> if top bit set, then number of subframes per second can be deduced</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">pulses</span><span class="plain"> >= </span><span class="constant">0x8000</span><span class="plain">) {</span>
|
|
<span class="comment"> First byte is a negative number for the frames per second</span>
|
|
<span class="comment"> Second byte is the number of subframes in each frame</span>
|
|
<span class="identifier">frames_per_second</span><span class="plain"> = (256 - (</span><span class="identifier">pulses</span><span class="plain"> & </span><span class="constant">0xff</span><span class="plain">));</span>
|
|
<span class="identifier">subframes_per_frame</span><span class="plain"> = (</span><span class="identifier">pulses</span><span class="plain"> >> </span><span class="constant">8</span><span class="plain">);</span>
|
|
<span class="identifier">clocks_per_second</span><span class="plain"> = </span><span class="identifier">frames_per_second</span><span class="plain"> * </span><span class="identifier">subframes_per_frame</span><span class="plain">;</span>
|
|
<span class="identifier">LOG</span><span class="plain">(</span><span class="string">"frames_per_second = %d\n"</span><span class="plain">, </span><span class="identifier">frames_per_second</span><span class="plain">);</span>
|
|
<span class="identifier">LOG</span><span class="plain">(</span><span class="string">"subframes_per_frame = %d\n"</span><span class="plain">, </span><span class="identifier">subframes_per_frame</span><span class="plain">);</span>
|
|
<span class="identifier">LOG</span><span class="plain">(</span><span class="string">"clocks_per_second = %d\n"</span><span class="plain">, </span><span class="identifier">clocks_per_second</span><span class="plain">);</span>
|
|
|
|
<span class="comment"> Number of pulses per quarter note unknown</span>
|
|
<span class="identifier">pulses</span><span class="plain"> = </span><span class="constant">0</span><span class="plain">;</span>
|
|
<span class="plain">} </span><span class="reserved">else</span><span class="plain"> {</span>
|
|
<span class="comment"> unknown values</span>
|
|
<span class="identifier">frames_per_second</span><span class="plain"> = </span><span class="constant">0</span><span class="plain">;</span>
|
|
<span class="identifier">subframes_per_frame</span><span class="plain"> = </span><span class="constant">0</span><span class="plain">;</span>
|
|
<span class="identifier">clocks_per_second</span><span class="plain"> = </span><span class="constant">0</span><span class="plain">;</span>
|
|
<span class="identifier">LOG</span><span class="plain">(</span><span class="string">"pulses per quarter note = %d\n"</span><span class="plain">, </span><span class="identifier">pulses</span><span class="plain">);</span>
|
|
<span class="plain">}</span>
|
|
|
|
<span class="comment"> Skip any remaining bytes in the MThd chunk</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">fseek</span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, (</span><span class="reserved">long</span><span class="plain">) (</span><span class="identifier">length</span><span class="plain"> - </span><span class="constant">6</span><span class="plain">), </span><span class="identifier">SEEK_CUR</span><span class="plain">) != </span><span class="constant">0</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
|
|
|
|
<span class="comment"> Keep reading chunks, looking for <code class="display"><span class="extract">"MTrk"</span></code></span>
|
|
<span class="reserved">do</span><span class="plain"> {</span>
|
|
<span class="comment"> Read chunk signature and length</span>
|
|
<span class="reserved">if</span><span class="plain"> (!</span><span class="functiontext"><a href="6-bf.html#SP1">BinaryFiles::read_int32</a></span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, &</span><span class="identifier">sig</span><span class="plain">)) {</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">feof</span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">)) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">TRUE</span><span class="plain">;</span>
|
|
<span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
|
|
<span class="plain">}</span>
|
|
<span class="reserved">if</span><span class="plain"> (!</span><span class="functiontext"><a href="6-bf.html#SP1">BinaryFiles::read_int32</a></span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, &</span><span class="identifier">length</span><span class="plain">)) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
|
|
|
|
<span class="identifier">start_of_chunk_data</span><span class="plain"> = (</span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain">) </span><span class="identifier">ftell</span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">);</span>
|
|
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">sig</span><span class="plain"> == </span><span class="constant">0x4D54726B</span><span class="plain">) { </span><span class="comment"> <code class="display"><span class="extract">"MTrk"</span></code></span>
|
|
<span class="identifier">LOG</span><span class="plain">(</span><span class="string">"track starts\n"</span><span class="plain">);</span>
|
|
<span class="comment"> Read each event, looking for information before the real tune starts, e.g., tempo</span>
|
|
<span class="reserved">do</span><span class="plain"> {</span>
|
|
<span class="comment"> Read the number of clocks since the previous event</span>
|
|
<span class="reserved">if</span><span class="plain"> (!</span><span class="functiontext"><a href="6-bf.html#SP4">BinaryFiles::read_variable_length_integer</a></span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, &</span><span class="identifier">clocks</span><span class="plain">))</span>
|
|
<span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
|
|
|
|
<span class="comment"> We bail out when the track starts</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">clocks</span><span class="plain"> > </span><span class="constant">0</span><span class="plain">) </span><span class="reserved">break</span><span class="plain">;</span>
|
|
|
|
<span class="comment"> Read the MIDI Status byte</span>
|
|
<span class="reserved">if</span><span class="plain"> (!</span><span class="functiontext"><a href="6-bf.html#SP1">BinaryFiles::read_int8</a></span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, &</span><span class="identifier">status</span><span class="plain">)) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
|
|
|
|
<span class="comment"> Start or continuation of system exclusive data</span>
|
|
<span class="reserved">if</span><span class="plain"> ((</span><span class="identifier">status</span><span class="plain"> == </span><span class="constant">0xF0</span><span class="plain">) || (</span><span class="identifier">status</span><span class="plain"> == </span><span class="constant">0xF7</span><span class="plain">)) {</span>
|
|
<span class="comment"> Read length of system exclusive event data</span>
|
|
<span class="reserved">if</span><span class="plain"> (!</span><span class="functiontext"><a href="6-bf.html#SP4">BinaryFiles::read_variable_length_integer</a></span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, &</span><span class="identifier">sysex_length</span><span class="plain">)) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
|
|
|
|
<span class="comment"> Skip sysex event</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">fseek</span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, (</span><span class="reserved">long</span><span class="plain">) </span><span class="identifier">sysex_length</span><span class="plain">, </span><span class="identifier">SEEK_CUR</span><span class="plain">) != </span><span class="constant">0</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
|
|
<span class="plain">} </span><span class="reserved">else</span><span class="plain"> </span><span class="reserved">if</span><span class="plain"> (</span><span class="identifier">status</span><span class="plain"> == </span><span class="constant">0xFF</span><span class="plain">) { </span><span class="comment"> Non-MIDI event</span>
|
|
<span class="comment"> Read the Non-MIDI event type and length</span>
|
|
<span class="reserved">if</span><span class="plain"> (!</span><span class="functiontext"><a href="6-bf.html#SP1">BinaryFiles::read_int8</a></span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, &</span><span class="identifier">non_midi_event</span><span class="plain">)) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
|
|
<span class="reserved">if</span><span class="plain"> (!</span><span class="functiontext"><a href="6-bf.html#SP4">BinaryFiles::read_variable_length_integer</a></span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, &</span><span class="identifier">non_midi_event_length</span><span class="plain">))</span>
|
|
<span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
|
|
|
|
<span class="identifier">start_of_non_midi_data</span><span class="plain"> = (</span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain">) </span><span class="identifier">ftell</span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">);</span>
|
|
|
|
<span class="reserved">switch</span><span class="plain">(</span><span class="identifier">non_midi_event</span><span class="plain">) {</span>
|
|
<span class="reserved">case</span><span class="plain"> </span><span class="constant">0x01</span><span class="identifier">:</span><span class="plain"> </span><span class="comment"> Comment text</span>
|
|
<span class="reserved">case</span><span class="plain"> </span><span class="constant">0x02</span><span class="identifier">:</span><span class="plain"> </span><span class="comment"> Copyright text</span>
|
|
<span class="reserved">case</span><span class="plain"> </span><span class="constant">0x03</span><span class="identifier">:</span><span class="plain"> </span><span class="comment"> Track name</span>
|
|
<span class="reserved">case</span><span class="plain"> </span><span class="constant">0x04</span><span class="identifier">:</span><span class="plain"> { </span><span class="comment"> Instrument name</span>
|
|
<span class="reserved">char</span><span class="plain"> </span><span class="identifier">text</span><span class="plain">[257];</span>
|
|
<span class="reserved">if</span><span class="plain"> (!</span><span class="functiontext"><a href="6-bf.html#SP6">BinaryFiles::read_string</a></span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, </span><span class="identifier">text</span><span class="plain">, </span><span class="identifier">non_midi_event_length</span><span class="plain">))</span>
|
|
<span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
|
|
<span class="identifier">LOG</span><span class="plain">(</span><span class="string">"%d: %s\n"</span><span class="plain">, </span><span class="identifier">non_midi_event</span><span class="plain">, </span><span class="identifier">text</span><span class="plain">);</span>
|
|
<span class="reserved">break</span><span class="plain">;</span>
|
|
<span class="plain">}</span>
|
|
|
|
<span class="reserved">case</span><span class="plain"> </span><span class="constant">0x51</span><span class="identifier">:</span><span class="plain"> </span><span class="comment"> Tempo change</span>
|
|
<span class="reserved">case</span><span class="plain"> </span><span class="constant">0x58</span><span class="identifier">:</span><span class="plain"> </span><span class="comment"> Time signature</span>
|
|
<span class="reserved">case</span><span class="plain"> </span><span class="constant">0x59</span><span class="identifier">:</span><span class="plain"> </span><span class="comment"> Key signature</span>
|
|
<span class="reserved">break</span><span class="plain">;</span>
|
|
<span class="plain">}</span>
|
|
|
|
<span class="comment"> Skip non-midi event</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">fseek</span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">,</span>
|
|
<span class="plain">(</span><span class="reserved">long</span><span class="plain">) (</span><span class="identifier">start_of_non_midi_data</span><span class="plain"> + </span><span class="identifier">non_midi_event_length</span><span class="plain">), </span><span class="identifier">SEEK_SET</span><span class="plain">) != </span><span class="constant">0</span><span class="plain">)</span>
|
|
<span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
|
|
<span class="plain">} </span><span class="reserved">else</span><span class="plain"> {</span>
|
|
<span class="comment"> Real MIDI data found: we've read all we can so bail out at this point</span>
|
|
<span class="reserved">break</span><span class="plain">;</span>
|
|
<span class="plain">}</span>
|
|
<span class="plain">}</span>
|
|
<span class="reserved">while</span><span class="plain"> (</span><span class="constant">TRUE</span><span class="plain">);</span>
|
|
<span class="plain">}</span>
|
|
|
|
<span class="comment"> Seek to start of next chunk</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">fseek</span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">, (</span><span class="reserved">long</span><span class="plain">) (</span><span class="identifier">start_of_chunk_data</span><span class="plain"> + </span><span class="identifier">length</span><span class="plain">), </span><span class="identifier">SEEK_SET</span><span class="plain">) != </span><span class="constant">0</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
|
|
|
|
<span class="comment"> Reached end of file</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">feof</span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">)) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">TRUE</span><span class="plain">;</span>
|
|
|
|
<span class="comment"> Did we try to seek beyond the end of the file?</span>
|
|
<span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">position_in_file</span><span class="plain"> = (</span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain">) </span><span class="identifier">ftell</span><span class="plain">(</span><span class="identifier">pFile</span><span class="plain">);</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">position_in_file</span><span class="plain"> < (</span><span class="identifier">start_of_chunk_data</span><span class="plain"> + </span><span class="identifier">length</span><span class="plain">)) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">TRUE</span><span class="plain">;</span>
|
|
<span class="plain">}</span>
|
|
<span class="reserved">while</span><span class="plain"> (</span><span class="constant">TRUE</span><span class="plain">);</span>
|
|
|
|
<span class="reserved">return</span><span class="plain"> </span><span class="constant">TRUE</span><span class="plain">;</span>
|
|
<span class="plain">}</span>
|
|
</pre>
|
|
|
|
<p class="inwebparagraph"></p>
|
|
|
|
<hr class="tocbar">
|
|
<ul class="toc"><li><a href="6-id.html">Back to 'Image Dimensions'</a></li><li><i>(This section ends Chapter 6: Media.)</i></li></ul><hr class="tocbar">
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