迅雷Aplayer集成soundtouch做变调，爆音

[早知今日何必当猪]

本来想用迅雷Aplayer（http://aplayer.open.xunlei.com/）的插件系统写一个变调插件，结果在转换位数哪里怎么也弄不对，主要原因是一个是char类型的，一个是float类型的，也不知道哪里还有错误，改了两天，结果不是爆音就是无声，反正调没变。

struct AUDIO_FRAME_INFO //这个是调用时传入的结构体，里面有些东西不知道什么意思，
                                   //这些英文表述不是很清楚，官方又没说明
{
	int				channel; //声道？
	int				bit_per_sample; //比特率？
	BOOL			is_float; //？
	int				sample_count; //？
	BYTE *			frame; //这个是单声道数据还是所有声道数据？
	__int64			time_stamp; //？
};
float *Convert16BitToFloat(BYTE *input, int *inputSamples)
{
	*inputSamples = *inputSamples / 2; // 16 bit input, so 2 bytes per sample
	float *output = new float[*inputSamples];
	int outputIndex = 0;
	for (int n = 0; n < *inputSamples; n++)
	{
		short sample = input[n * 2] | (input[n * 2 + 1] << 8);
		output[outputIndex++] = sample / 32768.0f;
	}
	return output;
}
float *Convert24BitToFloat(BYTE *input, int *inputSamples)
{
	*inputSamples = *inputSamples / 3; // 24 bit input
	float *output = new float[*inputSamples];
	int outputIndex = 0;
	for (int n = 0; n < *inputSamples; n++)
	{
		// copy 3 bytes in
		int sample = input[n * 3] | (input[n * 3 + 1] << 8) | (input[n * 3 + 2] << 16 | 0x0 << 24);
		output[outputIndex++] = sample / 16777216.0f;
	}
	return output;
}
EXPORT_FUNCTION void APlayerPluginAudioFrame(AUDIO_FRAME_INFO * pFrame)
{
	//g_nAudioFrameCount++;
	//UpdateUI();

	HANDLE mSoundTouch = soundtouch_createInstance();//初始化对象
	soundtouch_setChannels(mSoundTouch,1);//设置声道
	soundtouch_setSampleRate(mSoundTouch, pFrame->bit_per_sample);//设置采样频率
	soundtouch_setPitchSemiTones(mSoundTouch, 10);//设置音调


	// 将解码后的buffer(uint8*)转换为soundtouch::SAMPLETYPE，也就是singed int 16
	auto len = pFrame->sample_count * pFrame->bit_per_sample;
	float *touch_buffer = Convert24BitToFloat(pFrame->frame, &len);//这里不知道是24位
                                                                // 还是16位
	soundtouch_putSamples(mSoundTouch, touch_buffer, len);
	int receiveCount = 0;
	int pcm_data_size = 0;
	do
	{
		// 接收处理后的sample
		receiveCount = soundtouch_receiveSamples(mSoundTouch, touch_buffer, len);
		for (int i = 0; i < receiveCount; i++)//网上找到，不知道写对没有，原来是*2的结果转
                                                //完还原时这样就少了一半，很奇怪
		{
			// adjust volume
			float sample32 = touch_buffer[receiveCount] * 1;
			// clip
			if (sample32 > 1.0f)
				sample32 = 1.0f;
			if (sample32 < -1.0f)
				sample32 = -1.0f;
			pFrame->frame[pcm_data_size] = (short)(sample32 * 32767);
			pcm_data_size++;
		}
	} while (receiveCount != 0);
	soundtouch_flush(mSoundTouch);
	do
	{
		// 接收处理后的sample
		receiveCount = soundtouch_receiveSamples(mSoundTouch, touch_buffer, len);
		for (int i = 0; i < receiveCount; i++)//和上面一样少了一半
		{
			// adjust volume
			float sample32 = touch_buffer[receiveCount] * 1;
			// clip
			if (sample32 > 1.0f)
				sample32 = 1.0f;
			if (sample32 < -1.0f)
				sample32 = -1.0f;
			pFrame->frame[pcm_data_size] = (short)(sample32 * 32767);
			pcm_data_size++;
		}
	} while (receiveCount != 0);
	pFrame->sample_count = pcm_data_size / pFrame->bit_per_sample;
	delete[](touch_buffer);
}