MP3软件解码

爱好单片机 · 发表于 2016-1-6 13:17:34

我在论坛里面找了个heilx软件解码的程序，数据是通过串口接收的，
程序查找同步字都成功了，解码函数也执行通过就是没有看到输出PCM数据，不知道PCM数据到底是在那里输出的

大家帮忙看看在那个位置输出PCM

/**
  * @brief  mp3_player 进行mp3文件解码、播放
  * @param  filename:要播放的文件路径
  * @retval none
  */
//static void mp3_player(const char *filename)
void mp3_player(void)
{
int err,/* i,*/ outputSamps;//, current_sample_rate = 0;

int read_offset = 0; /* 读偏移指针 */
int bytes_left = 0; /* 剩余字节数 */
unsigned long Frames = 0;       /* mP3帧计数 */
unsigned char *read_ptr = buffer;       /* 缓冲区指针 */
HMP3Decoder Mp3Decoder; /* mp3解码器指针 */

//打开成功
//初始化MP3解码器
Mp3Decoder = MP3InitDecoder();

//获取输入数据流，调用helix库解码，输出PCM数据，约20ms完成一次循环
//开始进入播放状态,期间中断会修改touch_even状态
while(1) //循环1，如果touch_even不是切歌状态则继续呆在循环体里
{
//有时出现解码错误，错误后继续在本循环体内，继续播放

//
read_ptr  = buffer;
bytes_left = 0;

//
Communication();

if(UART1_Index3 < 1126)
break;
read_ptr    = buffer; //指向mp3输入流
bytes_left = UART1_Index3; //实际读到的输入流大小大小
UART1_Index3 = 0;
bufflag    = 0;
// UART1_Index3 = 0;

//按帧处理
while(1)
{

read_offset = MP3FindSyncWord(read_ptr, bytes_left); //寻找帧同步，返回第一个同步字的位置
if(read_offset < 0) //没有找到同步字
{
break; //跳出循环2，回到循环1
}

read_ptr += read_offset; //偏移至同步字的位置
bytes_left -= read_offset; //同步字之后的数据大小

//
err = MP3Decode(Mp3Decoder, &read_ptr, &bytes_left, outBuf[bufflag], 0); //开始解码参数：mp3解码结构体、输入流指针、输入流大小、输出流指针、数据格式
Frames++;

if (err != ERR_MP3_NONE) //错误处理
{
switch (err)
{
case ERR_MP3_INDATA_UNDERFLOW:
// printf("ERR_MP3_INDATA_UNDERFLOW\r\n");
read_ptr = buffer;
//fres = f_read(&file, read_ptr, sizeof(buffer), &rw_num);
bytes_left = rw_num;
break;

case ERR_MP3_MAINDATA_UNDERFLOW:
/* do nothing - next call to decode will provide more mainData */
// printf("ERR_MP3_MAINDATA_UNDERFLOW\r\n");
break;

default:
// printf("UNKNOWN ERROR:%d\r\n", err);

// 跳过此帧
if (bytes_left > 0)
{
bytes_left --;
read_ptr ++;
}
break;
}
}
else //解码无错误，准备把数据输出到PCM
{
MP3GetLastFrameInfo(Mp3Decoder, &Mp3FrameInfo); //获取解码信息

/* 输出到DAC */
outputSamps = Mp3FrameInfo.outputSamps; //PCM数据个数

if (outputSamps > 0)
{
//
if(1 == Mp3FrameInfo.nChans)
Convert_Mono(  &outBuf[bufflag][0]);
else
Convert_Stereo(&outBuf[bufflag][0]);
// if (Mp3FrameInfo.nChans == 1) //单声道
// {
//单声道数据需要复制一份到另一个声道
// for (i = outputSamps - 1; i >= 0; i--)
// {
// outBuf[bufflag][i * 2] = outBuf[bufflag];
// outBuf[bufflag][i * 2 + 1] = outBuf[bufflag];
// }
// outputSamps *= 2;
// }
// else
// {

// }

//非单声道数据可直接由DMA传输到IIS交给DAC
/* 等待DMA播放完，这段时间我们可以干其他的事，扫描事件进行处理 */
// while((DMA1_Channel5->CCR&DMA_CCR1_EN) && !(DMA1->ISR&DMA1_IT_TC5))
// {

// static uint8_t i=0;
// if(i==0)
// {
//  PCM1770_VolumeSet(voice);
//    i++;
// }

// even_process();
// }

/*DMA传输完毕*/
// DMA_ClearFlag(DMA1_FLAG_TC5 | DMA1_FLAG_TE5);
// DMA_I2S_Configuration((uint32_t)outBuf[bufflag], outputSamps);
// bufflag = 1 -bufflag; //切换buffer

}
}

// if(file.fptr==file.fsize) //如果指针指向了文件尾，表示数据全部读完
// {
// printf("END\r\n");
// if(play_index<file_num-1) //自动开始下一首歌曲
// {
// play_index++;
// player_state = S_SWITCH; //进入切歌状态，跳出
//}
//else
//{
// play_index = 0;
// player_state = S_SWITCH;
//}

// break; //跳出这首歌的播放状态 while break;
// }

}

}

// f_close(&file); //结束播放本歌曲，关闭文件
// MP3FreeDecoder(Mp3Decoder);
// I2S_Stop();

}

程序已经执行到了红色区域了，输出PCM个数是2304个PCM，但是我查看outbuf缓存区全部00不知道是怎么回事

ricefat · 发表于 2016-1-6 14:12:50

http://www.openedv.com/thread-21204-1-1.html希望能给你帮助

爱好单片机 · 发表于 2016-1-6 14:30:12

ricefat 发表于 2016-1-6 14:12
http://www.openedv.com/thread-21204-1-1.html希望能给你帮助

谢谢的的回答，我看了你的程序，但是不知道你的PCM数据是不是放到,buffer1和,buffer2缓存区里面的，是不是红色区域的代码，PCM数据就已经出错到,buffer缓存区里面的
/**
  * @brief  Start wave player
  * @param  None
  * @retval None
  */
void WavePlayerStart(void)
{
  u32 br;
FRESULT res;
uint16_t i;

char path[] = "0:/";

  //buffer_switch = 1;

hMP3Decoder=MP3InitDecoder();//初始化MP3解码器

  /* Get the read out protection status */
  if (f_opendir(&dir, path)!= FR_OK)
  {
while(1)
{
   STM_EVAL_LEDToggle(LED5);
   Delay(10);
}
  }
  else
  {
if (WaveRecStatus == 1)
{
   WaveFileName = REC_WAVE_NAME;
}
else
{
   WaveFileName = "0:audio.mp3";//WAVE_NAME; 名字改下
}
/* Open the wave file to be played */
if (f_open(&fileR, WaveFileName , FA_READ) != FR_OK)
{
   STM_EVAL_LEDOn(LED5);
   Command_index = 1;
}
else
{

   //复位计数器
bytesLeft=0;
readPtr=readBuf;
res=f_read(&fileR,readBuf,READBUF_SIZE,&br);
bytesLeft += br;
//if(res!=FR_OK||br==0) break;
XferCplt=1;
buffer_switch=0;
init=0;
WavePlayerInit((u32)44100);
while(1)
{
offset=MP3FindSyncWord(readPtr, bytesLeft);//寻找下一帧头 assume EOF if no sync found
if(offset<0)break;
readPtr+=offset; //data start point
bytesLeft-=offset; //in buffer
if(bytesLeft<READBUF_SIZE)
{
memmove(readBuf,readPtr,bytesLeft);
res=f_read(&fileR,readBuf+bytesLeft,READBUF_SIZE-bytesLeft,&br);
if((res)||(br==0)) break;
if(br<READBUF_SIZE-bytesLeft)
memset(readBuf+bytesLeft+br,0,READBUF_SIZE-bytesLeft-br);
bytesLeft=READBUF_SIZE;
readPtr=readBuf;
}
MP3GetLastFrameInfo(hMP3Decoder, &mp3FrameInfo);
从这里开始是不是PCM已经转换完成了，准备送往DA转换

// if(init==0)//根据MP3帧信息初始化音频接口  //
// {
// WavePlayerInit((u32)mp3FrameInfo.samprate);
// init=1;
// }

while(XferCplt==0);
XferCplt=0;
if(buffer_switch == 0)
{

Audio_MAL_Play((u32)buffer2,BUFF_SIZE*2);

//Decbuf=buffer1;
MP3Decode(hMP3Decoder,&readPtr,&bytesLeft,buffer1,0);
//Convert_Stereo(buffer1);
buffer_switch = 1;
}
else
{
Audio_MAL_Play((u32)buffer1,BUFF_SIZE*2);
//Decbuf=buffer2;
MP3Decode(hMP3Decoder,&readPtr,&bytesLeft,buffer2,0);
//Convert_Stereo(buffer2);
buffer_switch = 0;
}
}

}
  }
}

ricefat · 发表于 2016-1-6 14:36:53

爱好单片机发表于 2016-1-6 14:30
谢谢的的回答，我看了你的程序，但是不知道你的PCM数据是不是放到,buffer1和,buffer2缓存区里面的，是不 ...

解码是这句，前面只是读取mp3文件用的，
MP3Decode(hMP3Decoder,&readPtr,&bytesLeft,buffer1,0);
MP3Decode(hMP3Decoder,&readPtr,&bytesLeft,buffer2,0);
解码完成的PCM数据放在buffer1,2中，Audio_MAL_play实际是开启buffer到外部DAC的DMA通道

爱好单片机 · 发表于 2016-1-6 14:49:10

ricefat 发表于 2016-1-6 14:36
解码是这句，前面只是读取mp3文件用的，
MP3Decode(hMP3Decoder,&readPtr,&bytesLeft,buffer1,0);
MP3D ...

奥，我在看看，不知道为我执行过解码函数MP3Decode，buffer缓存区没有数据全部是00

爱好单片机 · 发表于 2016-1-6 18:41:43

ricefat 发表于 2016-1-6 14:36
解码是这句，前面只是读取mp3文件用的，
MP3Decode(hMP3Decoder,&readPtr,&bytesLeft,buffer1,0);
MP3D ...

问题还是没有找到，解码进入这个函数，我单步调试没有发现向buffer缓存区写PCM数据的，只有出错清空buffer缓存区，你能帮我看看这个函数那个位置是写如buffer缓存区的代码吗，
我把我程序执行的位置用红色标识出来。
/**********************************************************
* Function: MP3Decode
*
* Description: decode one frame of MP3 data
*
* Inputs:    valid MP3 decoder instance pointer (HMP3Decoder)
*             double pointer to buffer of MP3 data (containing headers + mainData)
*             number of valid bytes remaining in inbuf
*             pointer to outbuf, big enough to hold one frame of decoded PCM samples
*             flag indicating whether MP3 data is normal MPEG format (useSize = 0)
*             or reformatted as "self-contained" frames (useSize = 1)
*
* Outputs:    PCM data in outbuf, interleaved LRLRLR... if stereo
*             number of output samples = nGrans * nGranSamps * nChans
*             updated inbuf pointer, updated bytesLeft
*
* Return:    error code, defined in mp3dec.h (0 means no error, < 0 means error)
*
* Notes:    switching useSize on and off between frames in the same stream
*             is not supported (bit reservoir is not maintained if useSize on)
**********************************************************/
int MP3Decode(HMP3Decoder hMP3Decoder, unsigned char **inbuf, int *bytesLeft, short *outbuf, int useSize)
{
int offset, bitOffset, mainBits, gr, ch, fhBytes, siBytes, freeFrameBytes;
int prevBitOffset, sfBlockBits, huffBlockBits;
unsigned char *mainPtr;
MP3DecInfo *mp3DecInfo = (MP3DecInfo *)hMP3Decoder;

if (!mp3DecInfo)
return ERR_MP3_NULL_POINTER;

/* unpack frame header */ // 解析帧包头
fhBytes = UnpackFrameHeader(mp3DecInfo, *inbuf);
if (fhBytes < 0)
return ERR_MP3_INVALID_FRAMEHEADER; /* don't clear outbuf since we don't know size (failed to parse header) */ //不知道帧头无法解析 //
*inbuf += fhBytes;

/* unpack side info */
siBytes = UnpackSideInfo(mp3DecInfo, *inbuf);
if (siBytes < 0)
{
MP3ClearBadFrame(mp3DecInfo, outbuf);
return ERR_MP3_INVALID_SIDEINFO;
}
*inbuf += siBytes;
*bytesLeft -= (fhBytes + siBytes);

/* if free mode, need to calculate bitrate and nSlots manually, based on frame size */
if (mp3DecInfo->bitrate == 0 || mp3DecInfo->freeBitrateFlag)
{
if (!mp3DecInfo->freeBitrateFlag)
{
/* first time through, need to scan for next sync word and figure out frame size */
mp3DecInfo->freeBitrateFlag = 1;
mp3DecInfo->freeBitrateSlots = MP3FindFreeSync(*inbuf, *inbuf - fhBytes - siBytes, *bytesLeft);
if (mp3DecInfo->freeBitrateSlots < 0)
{
MP3ClearBadFrame(mp3DecInfo, outbuf);
return ERR_MP3_FREE_BITRATE_SYNC;
}
freeFrameBytes = mp3DecInfo->freeBitrateSlots + fhBytes + siBytes;
mp3DecInfo->bitrate = (freeFrameBytes * mp3DecInfo->samprate * 8) / (mp3DecInfo->nGrans * mp3DecInfo->nGranSamps);
}
mp3DecInfo->nSlots = mp3DecInfo->freeBitrateSlots + CheckPadBit(mp3DecInfo); /* add pad byte, if required */
}

/* useSize != 0 means we're getting reformatted (RTP) packets (see RFC 3119)
   *  - calling function assembles "self-contained" MP3 frames by shifting any main_data
   *    from the bit reservoir (in previous frames) to AFTER the sync word and side info
   *  - calling function should set mainDataBegin to 0, and tell us exactly how large this
   *    frame is (in bytesLeft)
   */
if (useSize)
{
mp3DecInfo->nSlots = *bytesLeft;
if (mp3DecInfo->mainDataBegin != 0 || mp3DecInfo->nSlots <= 0)
{
/* error - non self-contained frame, or missing frame (size <= 0), could do loss concealment here */
MP3ClearBadFrame(mp3DecInfo, outbuf);
return ERR_MP3_INVALID_FRAMEHEADER;
}

/* can operate in-place on reformatted frames */
mp3DecInfo->mainDataBytes = mp3DecInfo->nSlots;
mainPtr = *inbuf;
*inbuf += mp3DecInfo->nSlots;
*bytesLeft -= (mp3DecInfo->nSlots);
}
else
{
/* out of data - assume last or truncated frame */
if (mp3DecInfo->nSlots > *bytesLeft)
{
MP3ClearBadFrame(mp3DecInfo, outbuf);
return ERR_MP3_INDATA_UNDERFLOW;
}
/* fill main data buffer with enough new data for this frame */
if (mp3DecInfo->mainDataBytes >= mp3DecInfo->mainDataBegin)
{
/* adequate "old" main data available (i.e. bit reservoir) */
memmove(mp3DecInfo->mainBuf, mp3DecInfo->mainBuf + mp3DecInfo->mainDataBytes - mp3DecInfo->mainDataBegin, mp3DecInfo->mainDataBegin);
memcpy(mp3DecInfo->mainBuf + mp3DecInfo->mainDataBegin, *inbuf, mp3DecInfo->nSlots);

mp3DecInfo->mainDataBytes = mp3DecInfo->mainDataBegin + mp3DecInfo->nSlots;
*inbuf += mp3DecInfo->nSlots;
*bytesLeft -= (mp3DecInfo->nSlots);
mainPtr = mp3DecInfo->mainBuf;
}
else
{
/* not enough data in bit reservoir from previous frames (perhaps starting in middle of file) */
memcpy(mp3DecInfo->mainBuf + mp3DecInfo->mainDataBytes, *inbuf, mp3DecInfo->nSlots);
mp3DecInfo->mainDataBytes += mp3DecInfo->nSlots;
*inbuf += mp3DecInfo->nSlots;
*bytesLeft -= (mp3DecInfo->nSlots);
MP3ClearBadFrame(mp3DecInfo, outbuf);
return ERR_MP3_MAINDATA_UNDERFLOW;
}
}
bitOffset = 0;
mainBits = mp3DecInfo->mainDataBytes * 8;

/* decode one complete frame */
for (gr = 0; gr < mp3DecInfo->nGrans; gr++)
{
for (ch = 0; ch < mp3DecInfo->nChans; ch++)
{
/* unpack scale factors and compute size of scale factor block */
prevBitOffset = bitOffset;
offset = UnpackScaleFactors(mp3DecInfo, mainPtr, &bitOffset, mainBits, gr, ch);

sfBlockBits = 8*offset - prevBitOffset + bitOffset;
huffBlockBits = mp3DecInfo->part23Length[gr][ch] - sfBlockBits;
mainPtr += offset;
mainBits -= sfBlockBits;

if (offset < 0 || mainBits < huffBlockBits)
{
MP3ClearBadFrame(mp3DecInfo, outbuf);
return ERR_MP3_INVALID_SCALEFACT;
}

/* decode Huffman code words */
prevBitOffset = bitOffset;
offset = DecodeHuffman(mp3DecInfo, mainPtr, &bitOffset, huffBlockBits, gr, ch);
if (offset < 0)
{
MP3ClearBadFrame(mp3DecInfo, outbuf);
return ERR_MP3_INVALID_HUFFCODES;
}

mainPtr += offset;
mainBits -= (8*offset - prevBitOffset + bitOffset);
}
/* dequantize coefficients, decode stereo, reorder short blocks */
if (Dequantize(mp3DecInfo, gr) < 0)
{
MP3ClearBadFrame(mp3DecInfo, outbuf);
return ERR_MP3_INVALID_DEQUANTIZE;
}

/* alias reduction, inverse MDCT, overlap-add, frequency inversion */
for (ch = 0; ch < mp3DecInfo->nChans; ch++)
if (IMDCT(mp3DecInfo, gr, ch) < 0)
{
MP3ClearBadFrame(mp3DecInfo, outbuf);
return ERR_MP3_INVALID_IMDCT;
}

/* subband transform - if stereo, interleaves pcm LRLRLR */
if (Subband(mp3DecInfo, outbuf + gr*mp3DecInfo->nGranSamps*mp3DecInfo->nChans) < 0)
{
MP3ClearBadFrame(mp3DecInfo, outbuf);
return ERR_MP3_INVALID_SUBBAND;
}
}
return ERR_MP3_NONE;
}
我仿真一直跟踪没有看到一个地方是输出PCM数据的就是你的buffer缓存区，不知道为啥，是不是那里出错没有执行到，如果出错就会跳出这个函数的，我是整个函数顺利执行完成的