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<title>PulseAudio: Channel Maps</title>
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<h1><a class="anchor" name="channelmap">Channel Maps </a></h1><h2><a class="anchor" name="overv_sec">
Overview</a></h2>
Channel maps provide a way to associate channels in a stream with a specific speaker position. This relieves applications of having to make sure their channel order is identical to the final output.<h2><a class="anchor" name="init_sec">
Initialisation</a></h2>
A channel map consists of an array of <a class="el" href="channelmap_8h.html#f1cbe2738487c74f99e613779bd34bf2">pa_channel_position</a> values, one for each channel. This array is stored together with a channel count in a <a class="el" href="structpa__channel__map.html" title="A channel map which can be used to attach labels to specific channels of a stream...">pa_channel_map</a> structure.<p>
Before filling the structure, the application must initialise it using <a class="el" href="channelmap_8h.html#bf6d26acfe2b0b7147034c19925a714f" title="Initialize the specified channel map and return a pointer to it.">pa_channel_map_init()</a>. There are also a number of convenience functions for standard channel mappings:<p>
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<li><a class="el" href="channelmap_8h.html#f32466c8cb879edf9439ec35866760c6" title="Initialize the specified channel map for monoaural audio and return a pointer to...">pa_channel_map_init_mono()</a> - Create a channel map with only mono audio. </li>
<li><a class="el" href="channelmap_8h.html#15e329f5ecc28cfb7ea26324a8035d02" title="Initialize the specified channel map for stereophonic audio and return a pointer...">pa_channel_map_init_stereo()</a> - Create a standard stereo mapping. </li>
<li><a class="el" href="channelmap_8h.html#b7d13111387d169484853f713b68f9cc" title="Initialize the specified channel map for the specified number of channels using default...">pa_channel_map_init_auto()</a> - Create a standard channel map for up to six channels.</li>
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<h2><a class="anchor" name="conv_sec">
Convenience Functions</a></h2>
The library contains a number of convenience functions for dealing with channel maps:<p>
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<li><a class="el" href="channelmap_8h.html#5d4699c853806a999cbde869dbf7a7ad" title="Return non-zero of the specified channel map is considered valid.">pa_channel_map_valid()</a> - Tests if a channel map is valid. </li>
<li><a class="el" href="channelmap_8h.html#851c6c02f0cbfc193d9bacfe42110bd3" title="Compare two channel maps.">pa_channel_map_equal()</a> - Tests if two channel maps are identical. </li>
<li><a class="el" href="channelmap_8h.html#5baa37ac22ea08485b12fcce63a98abe" title="Make a humand readable string from the specified channel map.">pa_channel_map_snprint()</a> - Creates a textual description of a channel map. </li>
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