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| <title>音频实现</title> |
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| <p>本部分介绍了如何实现音频硬件抽象层 (HAL)，提供了有关配置音频策略（文件格式、代码组织、预处理效果）的详细信息，并说明了如何配置共享库（创建 <code>Android.mk</code> 文件）。</p> |
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| <h2 id="implementing">实现音频 HAL</h2> |
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| <p>音频 HAL 由以下接口组成：</p> |
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| <ul> |
| <li><code>hardware/libhardware/include/hardware/audio.h</code>：表示音频设备的主函数。</li> |
| <li><code>hardware/libhardware/include/hardware/audio_effect.h</code>：表示可应用于音频的效果，如缩混、回音或噪音抑制。</li> |
| </ul> |
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| <p>您必须实现所有接口。</p> |
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| <h2 id="headers">音频标头文件</h2> |
| <p>要查看您可以定义的属性的参考，请参阅音频标头文件：</p> |
| |
| <ul> |
| <li>在 Android 6.0 及更高版本中，请参阅 <code>system/media/audio/include/system/audio.h</code>。</li> |
| <li>在 Android 5.1 及更低版本中，请参阅 <code>system/core/include/system/audio.h</code>。</li> |
| </ul> |
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| <p>例如，在 <code>device/samsung/tuna/audio</code> 中参阅 Galaxy Nexus 的实现。</p> |
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| <h2 id="next-steps">后续步骤</h2> |
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| <p>除了实现音频 HAL 之外，您还必须创建<a href="/devices/audio/implement-policy.html">音频策略配置文件</a>，用于描述您的音频拓扑，并将 HAL 实现打包到<a href="/devices/audio/implement-shared-library.html">共享库</a>中。您还可以配置<a href="/devices/audio/implement-pre-processing.html">预处理效果</a>，如自动增益控制和噪音抑制。</p> |
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