自 2025 年 3 月 27 日起，我们建议您使用 android-latest-release 而非 aosp-main 构建 AOSP 并为其做出贡献。如需了解详情，请参阅 AOSP 的变更。
音频环回适配器
使用集合让一切井井有条
根据您的偏好保存内容并对其进行分类。
下面的图表和照片展示的是耳机连接器的音频环回dongle。Chrome 硬件团队设计了此电路和插头以进行功能测试，不过它还有许多其他用途。Android 音频团队使用它测量往返音频延迟时间，具体做法为：通过输出端发送已编码信号，然后在输入端查找匹配的信号。两者的间隔时间就是输入端加输出端的整体延迟时间。OboeTester 和 CTS 验证程序中都运用了这一技术。
PassMark Software 出售一款基于以下电路的环回适配器。这并非我们对该产品的推荐或背书。Google 与 PassMark 没有业务往来。
电路
图 1. 电路图
为了确保输出信号不会超出麦克风输入负荷，我们使其音量降低了约 20 分贝。麦克风极性开关可从电阻器负载得知，音频环回适配器是一种美标/CTIA 4 段式 TRRS 插头。
组装完成图
图 2. 组装完成图
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最后更新时间 (UTC)：2025-03-04。
[[["易于理解","easyToUnderstand","thumb-up"],["解决了我的问题","solvedMyProblem","thumb-up"],["其他","otherUp","thumb-up"]],[["没有我需要的信息","missingTheInformationINeed","thumb-down"],["太复杂/步骤太多","tooComplicatedTooManySteps","thumb-down"],["内容需要更新","outOfDate","thumb-down"],["翻译问题","translationIssue","thumb-down"],["示例/代码问题","samplesCodeIssue","thumb-down"],["其他","otherDown","thumb-down"]],["最后更新时间 (UTC)：2025-03-04。"],[],[],null,["# Audio loopback dongle\n\nThe diagram and photo below show an audio loopback\n[dongle](http://en.wikipedia.org/wiki/Dongle)\nfor the\n[headset connector](http://en.wikipedia.org/wiki/Phone_connector_(audio)).\nThe Chrome hardware team designed this circuit and plug for functional testing;\nhowever it has many other uses too. The Android audio team uses it to measure\n[round-trip audio latency](/docs/core/audio/latency/measure#measuringRoundTrip),\nby sending an encoded signal through the output and then looking for that matching signal on the input.\nThe time between the two is the combined input plus output latency.\nThis technique is used in [OboeTester](https://github.com/google/oboe/tree/main/apps/OboeTester/docs) and in CTS Verifier.\n\nA Loopback Dongle based on the circuit below is available from\n[PassMark Software](https://www.passmark.com/products/audio-loopback-plug/index.php).\nThis isn't a recommendation or an endorsement. Google does not have a business relationship with PassMark.\n\nCircuit\n-------\n\n\n**Figure 1.** circuit diagram\n\n\nTo ensure that the output signal will not overload the microphone input,\nwe cut it down by about 20dB.\nThe resistor loads tell the microphone polarity switch that\nthe audio loopback dongle is a US/CTIA pinout Tip Ring Ring Shield (TRRS) plug.\n\nAssembled\n---------\n\n\n**Figure 2.** Assembled"]]
