http://www.pic24.ru/ 2023-02-10T23:02:50+03:00 http://www.pic24.ru/ http://www.pic24.ru/lib/images/favicon.ico text/html 2008-07-21T00:31:18+03:00 http://www.pic24.ru/doku.php/en/mp3_dspic/ref/intro?rev=1216585878 <p> <br/> </p> <p> <a href="http://www.pic24.ru/lib/exe/detail.php/b_mp3_dspic.png?id=en%3Amp3_dspic%3Aref%3Aintro" class="media" title="b_mp3_dspic.png"><img src="http://www.pic24.ru/lib/exe/fetch.php/b_mp3_dspic.png" class="media" title="MP3 Decoder for dsPIC" alt="MP3 Decoder for dsPIC" /></a> </p> <h1><a name="dspic_mp3_decoder" id="dspic_mp3_decoder">dsPIC MP3 Decoder</a></h1> <div class="level1"> </div> <!-- SECTION "dsPIC MP3 Decoder" [61-93] --> <h2><a name="download" id="download">Download</a></h2> <div class="level2"> </div> <!-- SECTION "Download" [94-115] --> <h3><a name="last_version" id="last_version">Last version</a></h3> <div class="level3"> <ul> <li class="level1"><div class="li"> <strong>1.0.1042</strong> (16 july 2008) <a href="http://www.pic24.ru/lib/exe/fetch.php/mp3_dspic/ref/mp3_dspic_c30_1_0_1042.rar" class="media mediafile mf_rar" title="mp3_dspic:ref:mp3_dspic_c30_1_0_1042.rar">download</a> @ 1 МБ</div> <ul> <li class="level2"><div class="li"> First release on this site. Project contain source code of dsPIC MAD decoder, MPLAB project and test <acronym title="Motion Picture Experts Group Layer 3">MP3</acronym> files. File <code>..\doc\test_result.txt</code> contain reports of test streams decoding.</div> </li> </ul> </li> </ul> <hr /> <div class="plugin_uparrow"> <a href="#" title="Наверх"> <img src="http://www.pic24.ru/lib/plugins/uparrow/images/blue_arrow.png" alt="Наверх"/> </a> </div> </div> <!-- SECTION "Last version" [116-442] --> <h2><a name="description" id="description">Description</a></h2> <div class="level2"> <p> <acronym title="Motion Picture Experts Group Layer 3">MP3</acronym> decoder library project for Microchip DSC dsPIC is based on well known fixed-point <acronym title="Motion Picture Experts Group Layer 3">MP3</acronym> decoder <a href="http://www.underbit.com/products/mad/" class="urlextern" title="http://www.underbit.com/products/mad/" rel="nofollow">MAD</a>. Generally speaking this project based on another MAD port for TI TMS320C55xx that you can find in net (author: Grigory Abuladze). </p> <p> I rewrite all assemblers routines, check alingment (TI CCS assume that char size is 16 bit), check all endian-sensitive operations (TMS320 is big-endian, while dsPIC is little-endian). I use only static data allocation in my port. </p> <p> dsPIC33 MAD <acronym title="Motion Picture Experts Group Layer 3">MP3</acronym> decoder is available under the terms of the <a href="http://www.underbit.com/resources/license/gpl/" class="urlextern" title="http://www.underbit.com/resources/license/gpl/" rel="nofollow">GPL</a> </p> <div class="plugin_uparrow"> <a href="#" title="Наверх"> <img src="http://www.pic24.ru/lib/plugins/uparrow/images/blue_arrow.png" alt="Наверх"/> </a> </div> </div> <!-- SECTION "Description" [443-1101] --> <h2><a name="requirements" id="requirements">Requirements</a></h2> <div class="level2"> <dl> <dt><span class='term'> Flash</span></dt> <dd>~29 kB of code + ~17 kB of <code>const</code> section (totally 18% of dsPIC33FJ256GP710 flash size)</dd> <dt><span class='term'> SRAM</span></dt> <dd>~25 kB + ~1.5 kB for stack (totally 88% of dsPIC33FJ256GP710 SRAM)</dd> </dl> <p><br/> </p> <p> Today the only one Microchip DSC on which you can run this code is <a href="http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&amp;nodeId=1335&amp;dDocName=en024679" class="urlextern" title="http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&amp;nodeId=1335&amp;dDocName=en024679" rel="nofollow">dsPIC33FJ256GP710</a>. This is only because of SRAM memory requirements - any dsPIC33 have enough MIPS for decode low-rata <acronym title="Motion Picture Experts Group Layer 3">MP3</acronym> streams. </p> <div class="plugin_uparrow"> <a href="#" title="Наверх"> <img src="http://www.pic24.ru/lib/plugins/uparrow/images/blue_arrow.png" alt="Наверх"/> </a> </div> </div> <!-- SECTION "Requirements" [1102-1623] --> <h2><a name="productivity" id="productivity">Productivity</a></h2> <div class="level2"> <p> Project archive contain test <acronym title="Motion Picture Experts Group Layer 3">MP3</acronym> streams with different bitrates. Productivity estimated as time needed for stream decode (without audio buffer <code>read</code> and <code>write</code> functions) on 40 MIPS. </p> <p> The test results shows that current version can decode in real time: </p> <ul> <li class="level1"><div class="li"> all mono streams</div> </li> <li class="level1"><div class="li"> stereo streams with sample rate up to 32 kHz and bitrate up to 128 kbps</div> </li> </ul> <p> The dsPIC MAD decoder need about 33.6 MIPS for decode stereo stream 32 kHz @ 128 kbps and 6.8 MIPS for decode stereo stream 8 kHz @ 20 kbps. </p> <p> Full test report you can find in <code>..\doc\test_results.txt</code>. </p> <div class="plugin_uparrow"> <a href="#" title="Наверх"> <img src="http://www.pic24.ru/lib/plugins/uparrow/images/blue_arrow.png" alt="Наверх"/> </a> </div> </div> <!-- SECTION "Productivity" [1624-2220] --> <h2><a name="limitations" id="limitations">Limitations</a></h2> <div class="level2"> <p> The current decoder version have the following limitations: </p> <ul> <li class="level1"><div class="li"> MPEG1 Layer 1 and Layer 2 not supported</div> </li> <li class="level1"><div class="li"> 16-bit math is used</div> </li> <li class="level1"><div class="li"> bug in <code>mad_port_stereo_intensity_lsf()</code> function <img src="http://www.pic24.ru/lib/images/smileys/fixme.gif" class="middle" alt="FIXME" /></div> </li> </ul> <div class="plugin_uparrow"> <a href="#" title="Наверх"> <img src="http://www.pic24.ru/lib/plugins/uparrow/images/blue_arrow.png" alt="Наверх"/> </a> </div> </div> <!-- SECTION "Limitations" [2221-] -->