我在哪里可以从 Android 框架中获取原始 PCM 数据？

Question

Where can I get the original pcm data from the Android framework? I think I can get it from:

Write (const void * buffer, size_t userSize, bool blocking)

in /framework/av/media/libmedia/AudioTrack.cpp

However, it differs from the pcm data in the file before streaming service and the pcm data obtained in write.

I think it is like re-sampling.

Where can I get original pcm data?

Note:

• The sound source is a FLAC sound source.
• The Android version is 6.0.1.

Answer 1

You have better chance of tapping the pcm buffer at one layer below the android-framework layer - audio hal. Now that would be dependent on the hardware hence I can provide you with some probable examples:-

hardware/xxx/audio/hal/audio_hw.c (Where xxx is qcom in my case)
in_read() --> pcm_read()

external/tinyalsa/pcm.c
pcm_read()

Answer 2

AudioTrack.cpp 中的 PCM 数据将输入到 AudioMixer 和 AudioEffects 组件中以自定义效果，然后进入音频 HAL。