melt xml with keyframed audio

two_tracks.xml

<?xml version='1.0' encoding='utf-8'?>
<mlt title="Anonymous Submission" version="6.4.1" root="/tmp" producer="main bin" LC_NUMERIC="es_AR.UTF-8">
 <profile width="640" frame_rate_den="1" height="480" display_aspect_num="16" display_aspect_den="9" frame_rate_num="25" colorspace="709" sample_aspect_den="1" description="HD 1080p 25 fps" progressive="1" sample_aspect_num="1"/>
 <producer id="1" title="Anonymous Submission" out="2531" in="0">
  <property name="length">00:01:41:07</property>
  <property name="eof">pause</property>
  <property name="resource">/path/to/project/Clap_tap.mp3</property>
  <property name="meta.media.nb_streams">1</property>
  <property name="meta.media.0.stream.type">audio</property>
  <property name="meta.media.0.codec.sample_fmt">s16p</property>
  <property name="meta.media.0.codec.sample_rate">44100</property>
  <property name="meta.media.0.codec.channels">2</property>
  <property name="meta.media.0.codec.name">mp3</property>
  <property name="meta.media.0.codec.long_name">MP3 (MPEG audio layer 3)</property>
  <property name="meta.media.0.codec.bit_rate">128000</property>
  <property name="meta.attr.0.stream.encoder.markup">LAME3.98r</property>
  <property name="meta.attr.album.markup">Premiumbeat.com / Royalty Free Music</property>
  <property name="meta.attr.title.markup">Clap_tap</property>
  <property name="meta.attr.track.markup">1</property>
  <property name="meta.attr.Software.markup">LAME 64bits version 3.98.4 (http://www.mp3dev.org/)</property>
  <property name="meta.attr.artist.markup">Styve Bolduc</property>
  <property name="meta.attr.Length.markup">177763</property>
  <property name="meta.attr.date.markup">2013</property>
  <property name="seekable">1</property>
  <property name="audio_index">0</property>
  <property name="video_index">-1</property>
  <property name="mute_on_pause">1</property>
  <property name="mlt_service">avformat-novalidate</property>
  <property name="kdenlive:folderid">-1</property>
  <property name="kdenlive:file_size">1621080</property>
  <property name="kdenlive:file_hash">f5e1998dac4d3b88388848133a108627</property>
  <property name="global_feed">1</property>
 </producer>
 <producer id="2" out="849" in="0">
  <property name="length">850</property>
  <property name="eof">pause</property>
  <property name="resource">tmp2cXUu_.jpg</property>
  <property name="ttl">25</property>
  <property name="aspect_ratio">1</property>
  <property name="progressive">1</property>
  <property name="seekable">1</property>
  <property name="loop">1</property>
  <property name="meta.media.width">604</property>
  <property name="meta.media.height">339</property>
  <property name="mlt_service">pixbuf</property>
  <property name="kdenlive:folderid">-1</property>
  <property name="kdenlive:duration">125</property>
  <property name="kdenlive:file_size">35880</property>
  <property name="kdenlive:file_hash">4c43b461d8f773bce1f317861423d4bd</property>
 </producer>
 <playlist id="main bin">
  <property name="kdenlive:docproperties.audiotargettrack">2</property>
  <property name="kdenlive:docproperties.decimalPoint">,</property>
  <property name="kdenlive:docproperties.dirtypreviewchunks"/>
  <property name="kdenlive:docproperties.disablepreview">0</property>
  <property name="kdenlive:docproperties.documentid">1486483894735</property>
  <property name="kdenlive:docproperties.enableproxy">0</property>
  <property name="kdenlive:docproperties.generateimageproxy">0</property>
  <property name="kdenlive:docproperties.generateproxy">0</property>
  <property name="kdenlive:docproperties.kdenliveversion">16.12.1</property>
  <property name="kdenlive:docproperties.position">581</property>
  <property name="kdenlive:docproperties.previewchunks"/>
  <property name="kdenlive:docproperties.previewextension"/>
  <property name="kdenlive:docproperties.previewparameters"/>
  <property name="kdenlive:docproperties.profile">atsc_1080p_25</property>
  <property name="kdenlive:docproperties.proxyextension">mpg</property>
  <property name="kdenlive:docproperties.proxyimageminsize">2000</property>
  <property name="kdenlive:docproperties.proxyminsize">1000</property>
  <property name="kdenlive:docproperties.proxyparams">-vf scale=640:-1 -g 5 -qscale 6 -ab 128k -vcodec mpeg2video -acodec mp2</property>
  <property name="kdenlive:docproperties.version">0.95</property>
  <property name="kdenlive:docproperties.verticalzoom">1</property>
  <property name="kdenlive:docproperties.videotargettrack">3</property>
  <property name="kdenlive:docproperties.zonein">0</property>
  <property name="kdenlive:docproperties.zoneout">100</property>
  <property name="kdenlive:docproperties.zoom">7</property>
  <property name="kdenlive:documentnotes"/>
  <property name="kdenlive:clipgroups"/>
  <property name="xml_retain">1</property>
  <entry out="2531" producer="1" in="0"/>
  <entry out="124" producer="2" in="0"/>
 </playlist>
 <producer id="black" out="849" in="0">
  <property name="length">850</property>
  <property name="eof">pause</property>
  <property name="resource">black</property>
  <property name="aspect_ratio">1</property>
  <property name="mlt_service">colour</property>
  <property name="set.test_audio">0</property>
 </producer>
 <playlist id="black_track">
  <entry out="849" producer="black" in="0"/>
 </playlist>
 <playlist id="playlist1">
  <property name="kdenlive:track_name">Audio 2</property>
  <property name="kdenlive:audio_track">1</property>
 </playlist>
 <playlist id="playlist2">
  <property name="kdenlive:track_name">Audio 1</property>
  <property name="kdenlive:audio_track">1</property>
 </playlist>
 <producer id="1_playlist3" title="Anonymous Submission" out="2531" in="0">
  <property name="length">00:01:41:07</property>
  <property name="eof">pause</property>
  <property name="resource">/path/to/project/Clap_tap.mp3</property>
  <property name="audio_index">0</property>
  <property name="video_index">-1</property>
  <property name="mute_on_pause">1</property>
  <property name="mlt_service">avformat-novalidate</property>
  <property name="seekable">1</property>
  <property name="kdenlive:folderid">-1</property>
  <property name="kdenlive:file_size">1621080</property>
  <property name="kdenlive:file_hash">f5e1998dac4d3b88388848133a108627</property>
  <property name="global_feed">1</property>
  <property name="xml">was here</property>
  <property name="meta.media.nb_streams">1</property>
  <property name="meta.media.0.stream.type">audio</property>
  <property name="meta.media.0.codec.sample_fmt">s16p</property>
  <property name="meta.media.0.codec.sample_rate">44100</property>
  <property name="meta.media.0.codec.channels">2</property>
  <property name="meta.media.0.codec.name">mp3</property>
  <property name="meta.media.0.codec.long_name">MP3 (MPEG audio layer 3)</property>
  <property name="meta.media.0.codec.bit_rate">128000</property>
  <property name="meta.attr.0.stream.encoder.markup">LAME3.98r</property>
  <property name="meta.attr.album.markup">Premiumbeat.com / Royalty Free Music</property>
  <property name="meta.attr.title.markup">Clap_tap</property>
  <property name="meta.attr.track.markup">1</property>
  <property name="meta.attr.Software.markup">LAME 64bits version 3.98.4 (http://www.mp3dev.org/)</property>
  <property name="meta.attr.artist.markup">Styve Bolduc</property>
  <property name="meta.attr.Length.markup">177763</property>
  <property name="meta.attr.date.markup">2013</property>
 </producer>
 <playlist id="playlist3">
  <property name="kdenlive:track_name">Video 1</property>
  <entry out="499" producer="1_playlist3" in="0">
   <filter id="volume">
    <property name="window">75</property>
    <property name="max_gain">20dB</property>
    <property name="level">0=0;16=12;55=-22;136=-36;293=-36;336=-18;368=-16;409=27</property>
    <property name="mlt_service">volume</property>
    <property name="kdenlive_id">volume</property>
    <property name="tag">volume</property>
    <property name="kdenlive_ix">1</property>
    <property name="kdenlive_info"/>
   </filter>
  </entry>
  <entry out="348" producer="1_playlist3" in="0">
   <filter id="filter0">
    <property name="window">75</property>
    <property name="max_gain">20dB</property>
    <property name="level">0=0;29=-38;81=-49</property>
    <property name="mlt_service">volume</property>
    <property name="kdenlive_id">volume</property>
    <property name="tag">volume</property>
    <property name="kdenlive_ix">1</property>
    <property name="kdenlive_info"/>
    <property name="disable">1</property>
   </filter>
  </entry>
 </playlist>
 <playlist id="playlist4">
  <property name="kdenlive:track_name">Video 2</property>
 </playlist>
 <playlist id="playlist5">
  <property name="kdenlive:track_name">Video 3</property>
  <entry out="848" producer="2" in="0"/>
 </playlist>
 <tractor id="maintractor" title="Anonymous Submission" global_feed="1" out="849" in="0">
  <track producer="black_track"/>
  <track producer="playlist1" hide="video"/>
  <track producer="playlist2" hide="video"/>
  <track producer="playlist3"/>
  <track producer="playlist4"/>
  <track producer="playlist5"/>
  <transition id="transition0">
   <property name="a_track">0</property>
   <property name="b_track">1</property>
   <property name="mlt_service">mix</property>
   <property name="always_active">1</property>
   <property name="combine">1</property>
   <property name="internal_added">237</property>
  </transition>
  <transition id="transition1">
   <property name="a_track">0</property>
   <property name="b_track">2</property>
   <property name="mlt_service">mix</property>
   <property name="always_active">1</property>
   <property name="combine">1</property>
   <property name="internal_added">237</property>
  </transition>
  <transition id="transition2">
   <property name="a_track">0</property>
   <property name="b_track">3</property>
   <property name="mlt_service">mix</property>
   <property name="always_active">1</property>
   <property name="combine">1</property>
   <property name="internal_added">237</property>
  </transition>
  <transition id="transition3">
   <property name="a_track">0</property>
   <property name="b_track">3</property>
   <property name="compositing">0</property>
   <property name="distort">0</property>
   <property name="mlt_service">qtblend</property>
   <property name="internal_added">237</property>
  </transition>
  <transition id="transition4">
   <property name="a_track">0</property>
   <property name="b_track">4</property>
   <property name="mlt_service">mix</property>
   <property name="always_active">1</property>
   <property name="combine">1</property>
   <property name="internal_added">237</property>
  </transition>
  <transition id="transition5">
   <property name="a_track">0</property>
   <property name="b_track">4</property>
   <property name="compositing">0</property>
   <property name="distort">0</property>
   <property name="mlt_service">qtblend</property>
   <property name="internal_added">237</property>
  </transition>
  <transition id="transition6">
   <property name="a_track">0</property>
   <property name="b_track">5</property>
   <property name="mlt_service">mix</property>
   <property name="always_active">1</property>
   <property name="combine">1</property>
   <property name="internal_added">237</property>
  </transition>
  <transition id="transition7">
   <property name="a_track">0</property>
   <property name="b_track">5</property>
   <property name="compositing">0</property>
   <property name="distort">0</property>
   <property name="mlt_service">qtblend</property>
   <property name="internal_added">237</property>
  </transition>
 </tractor>
</mlt>