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I have a rooted HiSense GoogleTV which has HDMI IN and OUT ports.

What I want to do is to record about 10 secs of the audio from the HDMI IN (from the set-top box). I am new to this, so please bear with me.

  1. Is this possible to do this on a rooted device?

  2. Does the HDMI data get decrypted (due to HDCP) after the HDMI IN and re-encrypted before it is routed out via HDMI out?

  3. If I were to try to capture the audio frames on a regular Linux box, how should I go about it? What components should I look into? I cannot find any documentation that describes the low level architecture and details on how the HDMI IN signal gets routed to HDMI OUT.

  4. Can you please point to the Android framework code that actually does this routing from HDMI In to OUT? Basically, want to understand the flow of what happens to the audio signal during the transfer from the HDMI IN to the OUT.

I am not sure if my questions make sense, but I hope you can give me some pointers on where I should start.

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简短的回答：不可能。直通通过可信视频路径 SOC 与 android 完全隔离。您需要成为经过认证的 SOC 供应商才能接近信号。

于 2013-03-20T22:46:31.273 回答
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HDMI 输入设备应标识为AUDIO_DEVICE_IN_AUX_DIGITAL（请参阅audio.h），尽管我从未遇到具有 HDMI 输入的 Android 设备，因此无法验证。

音频路由由AudioPolicyManager. libhardware_legacy 中有一个AudioPolicyManagerBase，然后通常有一个特定于平台的AudioPolicyManager实现，它重载了一些基类的方法。找到此实现的位置取决于平台。在 Qualcomm 平台上，它通常位于源代码树中的 hardware/qcom/audio 下的某个位置。
执行AudioPolicyManager高级路由（例如将流类型和音频源映射到音频设备），然后使用AudioHardware实现和可能的其他特定于平台的类来执行低级路由（在硬件级别管理音频流，加载声学调整参数、与设备驱动程序的接口等）。

任何与 HDMI 输入相关的功能都可能是特定于供应商的，因此如果您希望能够查看，可能需要您的 Google TV 设备的完整源代码（即包括供应商在 vanilla Android 之上应用的所有补丁）处理 HDMI 音频输入的代码。

于 2013-03-20T21:00:18.610 回答
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由于 Google TV 实施了 HDCP，您将无法访问视频或音频输入。改变这一点的唯一方法，即使是在有根设备上，也是改变谷歌电视代码，可能还有 SOC HDMI 驱动程序，谷歌都没有开源。

于 2013-03-20T21:11:01.817 回答