Android audioflinger 录音、录像时PCM音频数据的获取

代码位置：src\frameworks\av\services\audioflinger\Threads.cpp

在bool AudioFlinger::RecordThread::threadLoop()；方法，

        // If an NBAIO source is present, use it to read the normal capture's data

        if (mPipeSource != 0) {

            size_t framesToRead = mBufferSize / mFrameSize;

            framesRead = mPipeSource->read(& mRsmpInBuffer[rear * mChannelCount],

                    framesToRead, AudioBufferProvider::kInvalidPTS);

            if (framesRead == 0) {

                // since pipe is non-blocking, simulate blocking input

                sleepUs = (framesToRead * 1000000LL) / mSampleRate;

            }

        // otherwise use the HAL / AudioStreamIn directly

        } else {

            ssize_t bytesRead = mInput->stream->read(mInput->stream,

                    & mRsmpInBuffer[rear * mChannelCount], mBufferSize);

            if (bytesRead < 0) {

                framesRead = bytesRead;

            } else {

                framesRead = bytesRead / mFrameSize;

            }

        }

PCM数据读入到 mRsmpInBuffer，将mRsmpInBuffer内容写到/data/test.pcm，通过cooledit就可以播放。

FILE *file = fopen("/data/test.pcm", "ab+");

        if(file == NULL) {

            ALOGE("open file failed!");

        } else {

            fwrite(&mRsmpInBuffer[rear * mChannelCount], mBufferSize, 1, file);

        }

        if(file != NULL)

        fclose(file);