Android Audio代码分析2

AudioTrack的使用示例中，用到了函数getMinBufferSize，今天把它倒出来，再嚼嚼。

*****************************************源码*************************************************

 static public int getMinBufferSize(int sampleRateInHz, int channelConfig, int audioFormat) {

        int channelCount = 0;

        switch(channelConfig) {

        case AudioFormat.CHANNEL_OUT_MONO:

        case AudioFormat.CHANNEL_CONFIGURATION_MONO:

            channelCount = 1;

            break;

        case AudioFormat.CHANNEL_OUT_STEREO:

        case AudioFormat.CHANNEL_CONFIGURATION_STEREO:

            channelCount = 2;

            break;

        default:

            loge("getMinBufferSize(): Invalid channel configuration.");

            return AudioTrack.ERROR_BAD_VALUE;

        }

        if ((audioFormat != AudioFormat.ENCODING_PCM_16BIT)

            && (audioFormat != AudioFormat.ENCODING_PCM_8BIT)) {

            loge("getMinBufferSize(): Invalid audio format.");

            return AudioTrack.ERROR_BAD_VALUE;

        }

        if ( (sampleRateInHz < 4000) || (sampleRateInHz > 48000) ) {

            loge("getMinBufferSize(): " + sampleRateInHz +"Hz is not a supported sample rate.");

            return AudioTrack.ERROR_BAD_VALUE;

        }

        int size = native_get_min_buff_size(sampleRateInHz, channelCount, audioFormat);

        if ((size == -1) || (size == 0)) {

            loge("getMinBufferSize(): error querying hardware");

            return AudioTrack.ERROR;

        }

        else {

            return size;

        }

    } www.2cto.com

***********************************************************************************************

源码路径：

frameworks\base\media\java\android\media\AudioTrack.java

###########################################说明##############################################################

先把自带的注释拿来看看吧：

    /**

     * Returns the minimum buffer size required for the successful creation of an AudioTrack

     * object to be c