移动设备的amr音频解码 - VC
移动设备很多都用的AMR格式的编码来压缩语音，用于存储和传输。但是用代码播放时，需要先解码。
以下就是解码代码：
#define MMS_IO
#ifdef MMS_IO
#define AMR_MAGIC_NUMBER "#!AMR\n"
#define MAX_PACKED_SIZE (MAX_SERIAL_SIZE / 8 + 2)
#endif
/* frame size in serial bitstream file (frame type + serial stream + flags) */
#define SERIAL_FRAMESIZE (1+MAX_SERIAL_SIZE+5)
BOOL AMRNBDecode(BYTE *pbAmrBuffer, DWORD dwAmrLen, BYTE **bOut, DWORD *dwOutLen, BOOL IsHadHeader)
{
Speech_Decode_FrameState *speech_decoder_state = NULL;
Word16 serial[SERIAL_FRAMESIZE]; /* coded bits */
Word16 synth[L_FRAME]; /* Synthesis */
UWord8 packed_bits[MAX_PACKED_SIZE];
Word16 packed_size[16] = { 12, 13, 15, 17, 19, 20, 26, 31, 5, 0, 0, 0, 0, 0, 0, 0 };
enum RXFrameType rx_type = (enum RXFrameType)0;
enum TXFrameType tx_type = (enum TXFrameType)0;
enum Mode mode = (enum Mode)0;
Word16 reset_flag = 0;
Word16 reset_flag_old = 1;
Word16 i;
UWord8 toc, q, ft;
if (NULL == pbAmrBuffer)
return FALSE;
BYTE *pbBuffer = pbAmrBuffer;
BOOL bRet = FALSE;
if (IsHadHeader)
{
/* read and verify magic number */
if (memcmp(pbBuffer, AMR_MAGIC_NUMBER, strlen(AMR_MAGIC_NUMBER)))
{
return FALSE;
}
pbBuffer += strlen(AMR_MAGIC_NUMBER);
dwAmrLen -= strlen(AMR_MAGIC_NUMBER);
}
BYTE *pbDecode = NULL;
DWORD dwDeLen = 0;
/*-----------------------------------------------------------------------*
* Initialization of decoder *
*-----------------------------------------------------------------------*/
if (Speech_Decode_Frame_init(&speech_decoder_state, "Decoder"))
return FALSE;
/*-----------------------------------------------------------------------*
* process serial bitstream frame by frame *
*-----------------------------------------------------------------------*/
while (1 == GetBytesFromBuffer(&pbBuffer, &dwAmrLen, sizeof(UWord8), &toc))
{
/* read rest of the frame based on ToC byte */
q = (toc >> 2) & 0x01;
ft = (toc >> 3) & 0x0F;
if (packed_size[ft] != GetBytesFromBuffer(&pbBuffer, &dwAmrLen, packed_size[ft], &packed_bits))
{
bRet = FALSE;
break;
}
rx_type = UnpackBits(q, ft, packed_bits, &mode, &serial[1]);
if (rx_type == RX_NO_DATA) {
mode = speech_decoder_state->prev_mode;
}
else {
speech_decoder_state->prev_mode = mode;
}
/* if homed: check if this frame is another homing frame */
if (reset_flag_old == 1)
{
/* only check until end of first subframe */
reset_flag = decoder_homing_frame_test_first(&serial[1], mode);
}
/* produce encoder homing frame if homed & input=decoder homing frame */
if ((reset_flag != 0) && (reset_flag_old != 0))
{
for (i = 0; i < L_FRAME; i++)
{
synth[i] = EHF_MASK;
}
}
else
{
/* decode frame */
Speech_Decode_Frame(speech_decoder_state, mode, &serial[1], rx_type, synth);
}
/* write synthesized speech */
pbDecode = (BYTE *)realloc(pbDecode, sizeof(Word16) * L_FRAME + dwDeLen);
memcpy(&pbDecode[dwDeLen], synth, sizeof(Word16) * L_FRAME);
dwDeLen += sizeof(Word16) * L_FRAME;
/* if not homed: check whether current frame is a homing frame */
if (reset_flag_old == 0)
{
/* check whole frame */
reset_flag = decoder_homing_frame_test(&serial[1], mode);
}
/* reset decoder if current frame is a homing frame */
if (reset_flag != 0)
{
Speech_Decode_Frame_reset(speech_decoder_state);
}
reset_flag_old = reset_flag;
bRet = TRUE;
}
Speech_Decode_Frame_exit(&speech_decoder_state);
if (bRet)
{
//建立文件头
WAVFILEHEADER *pHeader = CreateWavFileHeader(dwDeLen, 1, 8000, 16);
*dwOutLen = dwDeLen + sizeof(WAVFILEHEADER);
*bOut = new BYTE[*dwOutLen];
memcpy(*bOut, pHeader, sizeof(WAVFILEHEADER));
memcpy(*bOut + sizeof(WAVFILEHEADER), pbDecode, dwDeLen);
free(pHeader);
}
if (pbDecode)
free(pbDecode);
return bRet;
}
UINT GetBytesFromBuffer(BYTE **pBuffer, DWORD *dwOft, UINT dwRead, void *lpTarget)
{
if (*dwOft < dwRead)
return 0;
memcpy(lpTarget, *pBuffer, dwRead);
*dwOft -= dwRead;
*pBuffer += dwRead;
return dwRead;
}
WAVFILEHEADER *CreateWavFileHeader(int fileLength, short channel, int sampleRate, short bitPerSample)
{
WAVFILEHEADER *header = (WAVFILEHEADER *)malloc(sizeof(WAVFILEHEADER));
// RIFF
header->riff[0] = 'R';
header->riff[1] = 'I';
header->riff[2] = 'F';
header->riff[3] = 'F';
// file length
header->fileLength = fileLength + (44 - 8);
// WAVE
header->wavTag[0] = 'W';
header->wavTag[1] = 'A';
header->wavTag[2] = 'V';
header->wavTag[3] = 'E';
// fmt
header->fmt[0] = 'f';
header->fmt[1] = 'm';
header->fmt[2] = 't';
header->fmt[3] = ' ';
header->size = 16;
header->formatTag = 1;
header->channel = channel;
header->sampleRate = sampleRate;
header->bitPerSample = bitPerSample;
header->blockAlign = (short)(header->channel * header->bitPerSample / 8);
header->bytePerSec = header->blockAlign * header->sampleRate;
// data
header->data[0] = 'd';
header->data[1] = 'a';
header->data[2] = 't';
header->data[3] = 'a';
// data size
header->dataSize = fileLength;
return header;
}