aviplay.c

MP3 Player Source Code

/** \file aviplay.c Experimental functions to play sound track from AVIfile */


#define btUNKNOWN 0
#define btLIST 1
#define btSTR 2
#define btAUDIO 3


#define GetLongWord() {instream.b.b0 = FGetChar(); \
 instream.b.b1 = FGetChar();\
 instream.b.b2 = FGetChar();\
 instream.b.b3 = FGetChar();}

void GetAVIBlock(){

  xdata addressType instream;
  xdata unsigned char blockType = 0;
  bit isPadded = 0;
  
  GetLongWord();
  if ((instream.b.b2 == 'w') && (instream.b.b3 == 'b')){
    blockType = btAUDIO;
  }
  if (instream.l==1414744396){ //LIST
    blockType = btLIST;
  }
  GetLongWord();
  //instream.l should now contain the chunk size.
  //its length must be even by spec. if it's odd, a pad byte is 
  //in the file but its NOT part of chunk data.
  if (instream.b.b0&1){
    isPadded = 1; //There is a pad byte to make chunk len even
  }else{
    isPadded = 0;
  }
  
  
  if (blockType == btAUDIO){
    //--------THIS PACKET IS SENT TO VS10xx---------
    //superbly hilarious effects could happen if the avifile has
    //more than 1 soundtrack as all of them would be sent to VS10xx
    
    while(instream.l){
      unsigned char c;
      
      while ((instream.l>16)&&(dataBufPtr < diskSect.raw.buf+496)){
	//We have at least 16 octets of continuous stream in mem.
	if (!MP3_DREQ){
	  GREEN_LED = LED_ON;
	  while (!MP3_DREQ){
	    Mp3DeselectData();
	    AvailableProcessorTime();
	  }
	}
	GREEN_LED = LED_OFF;
	Mp3SelectData();
	SPIPutCharWithoutWaiting(*dataBufPtr++);
	SPIWait();
	SPIPutChar(*dataBufPtr++);
	SPIPutChar(*dataBufPtr++);
	SPIPutChar(*dataBufPtr++);
	SPIPutChar(*dataBufPtr++);
	SPIPutChar(*dataBufPtr++);
	SPIPutChar(*dataBufPtr++);
	SPIPutChar(*dataBufPtr++);
	SPIPutChar(*dataBufPtr++);
	SPIPutChar(*dataBufPtr++);
	SPIPutChar(*dataBufPtr++);
	SPIPutChar(*dataBufPtr++);
	SPIPutChar(*dataBufPtr++);
	SPIPutChar(*dataBufPtr++);
	SPIPutChar(*dataBufPtr++);
	SPIPutChar(*dataBufPtr++);
	instream.l-=16;
	fileSize-=16;
	SPIWait();	
      }
            
      MP3_XDCS=1;
      instream.l--;
      c=FGetChar(); //data comes first until end of sector and
                    //then a new sector is loaded automagically.
      MP3_XDCS=0;
      SPIPutCharWithoutWaiting(c);
      //SPIWait();	
    }    
    MP3_XDCS=1;
  }else if (blockType == btLIST){
    ConsoleWrite("\rAVI: List of ");
    GetLongWord();
    ConsolePutChar(instream.b.b0);
    ConsolePutChar(instream.b.b1);
    ConsolePutChar(instream.b.b2);
    ConsolePutChar(instream.b.b3);

  }else{
    //We don't need this chunk. Let's quickly skip over it.
    
    //Is pad byte insertion needed?
    if (isPadded){
      instream.l++; //instream.l contains chunk size
      isPadded = 0;
    }

    //Skip to the end of sector
    if (instream.l>(temp.i=diskSect.raw.buf+512-dataBufPtr)){
      //The packet continues after end of sector
      instream.l -= temp.i;
      fileSize -= temp.i;
      sectorAddress.l++; //Sector handled, go to next.
      dataBufPtr = 0; //Complete sector is handled.
    }
    
    //Skip unnecessary sectors
    if (instream.l>512){
      while (instream.l>512){
	sectorAddress.l++;
	instream.l -= 512;
	fileSize -= 512;
      }
      dataBufPtr = 0; //Initialize for next call to FGetChar();
    }

    //Read last sector into memory
    if (dataBufPtr == 0){
      ReadDiskSector(sectorAddress.l);
      dataBufPtr = diskSect.raw.buf;
    }
    while (instream.l--){
      dataBufPtr++;
    }    
  }//nothing interesting,skip block

  if (isPadded){
    FGetChar();
  }
      
}

/** Try to play an avi file at current sector.
 * Returns 0x11 if AVI header is not found,
 * 0 if the file is played. */
unsigned char PlayAvi(){

  ReadDiskSector(sectorAddress.l);

  //DumpDiskSector();

  if (diskSect.raw.buf[8]!='A') return 0x11;
  if (diskSect.raw.buf[9]!='V') return 0x11;
  if (diskSect.raw.buf[10]!='I') return 0x11;
  ConsoleWrite("\rPlayAvi()\r");

  dataBufPtr=diskSect.raw.buf+12;

  while(fileSize){
    GetAVIBlock();
  }

  return 0;
}