bitstream.c

MPEG-4编解码的实现(包括MPEG4视音频编解码)

  oldCurrentBit = stream->currentBit;
  result = BsGetBitChar(stream,data,numBit);
  stream->currentBit = oldCurrentBit;
  if (result)
    CommonWarning("BsGetBitAheadChar: error reading bit stream");

  return result;
}


/* BsGetBitAheadShort() */
/* Read bits from bit stream (short). */
/* (Current position in bit stream is NOT advanced !!!) */

int BsGetBitAheadShort (
  BsBitStream *stream,		/* in: bit stream */
  unsigned short *data,		/* out: bits read */
				/*      (may be NULL if numBit==0) */
  int numBit)			/* in: num bits to read */
				/*     [0..16] */
				/* returns: */
				/*  0=OK  1=error */
{
  long oldCurrentBit;
  int result;

  if (BSdebugLevel >= 3)
    printf("BsGetBitAheadShort: %s  id=%ld  numBit=%d\n",
	   (stream->file!=NULL)?"file":"buffer",stream->streamId,numBit);

  oldCurrentBit = stream->currentBit;
  result = BsGetBitShort(stream,data,numBit);
  stream->currentBit = oldCurrentBit;
  if (result)
    CommonWarning("BsGetBitAheadShort: error reading bit stream");

  return result;
}


/* BsGetBitAheadInt() */
/* Read bits from bit stream (int). */
/* (Current position in bit stream is NOT advanced !!!) */

int BsGetBitAheadInt (
  BsBitStream *stream,		/* in: bit stream */
  unsigned int *data,		/* out: bits read */
				/*      (may be NULL if numBit==0) */
  int numBit)			/* in: num bits to read */
				/*     [0..16] */
				/* returns: */
				/*  0=OK  1=error */
{
  long oldCurrentBit;
  int result;

  if (BSdebugLevel >= 3)
    printf("BsGetBitAheadInt: %s  id=%ld  numBit=%d\n",
	   (stream->file!=NULL)?"file":"buffer",stream->streamId,numBit);

  oldCurrentBit = stream->currentBit;
  result = BsGetBitInt(stream,data,numBit);
  stream->currentBit = oldCurrentBit;
  if (result)
    CommonWarning("BsGetBitAheadInt: error reading bit stream");

  return result;
}

long BsGetBufferFullness (BsBitBuffer *buffer)
{
  return (buffer->numBit);
}

/* BsGetBuffer() */
/* Read bits from bit stream to buffer. */
/* (Current position in bit stream is advanced !!!) */
/* (Buffer is cleared first - previous data in buffer is lost !!!) */

int BsGetBuffer (
  BsBitStream *stream,		/* in: bit stream */
  BsBitBuffer *buffer,		/* out: buffer read */
				/*      (may be NULL if numBit==0) */
  long numBit)			/* in: num bits to read */
				/* returns: */
				/*  0=OK  1=error */
{
  long i,numByte,numRemain;
  unsigned long data;

  if (BSdebugLevel >= 2) {
    printf("BsGetBuffer: %s  id=%ld  numBit=%ld  ",
	   (stream->file!=NULL)?"file":"buffer",
	   stream->streamId,numBit);
      if (buffer != NULL)
	printf("bufSize=%ld  bufAddr=0x%lx  ",
	       buffer->size,(unsigned long)buffer);
      else
	printf("(bufAddr=(NULL)  ");
    printf("curBit=%ld\n",stream->currentBit);
  }

  if (stream->write != 0)
    CommonExit(1,"BsGetBuffer: stream not in read mode");

  if (numBit == 0)
    return 0;

  if (stream->buffer[0] == buffer)
    CommonExit(1,"BsGetBuffer: can not get buffer from itself");
  if (numBit < 0 || numBit > buffer->size)
    CommonExit(1,"BsGetBuffer: number of bits out of range (%ld)",numBit);

  BsClearBuffer(buffer);

  numByte = bit2byte(numBit)-1;
  for (i=0; i<numByte; i++) {
    if (BsGetBit(stream,&data,BYTE_NUMBIT)) {
      if ( ! BSaacEOF || BSdebugLevel > 0  )
        CommonWarning("BsGetBuffer: error reading bit stream");
      buffer->numBit = i*BYTE_NUMBIT;
      return 1;
    }
    buffer->data[i] = data;
  }
  numRemain = numBit-numByte*BYTE_NUMBIT;
  if (BsGetBit(stream,&data,numRemain)) {
    if ( ! BSaacEOF || BSdebugLevel > 0  )
      CommonWarning("BsGetBuffer: error reading bit stream");
    buffer->numBit = numByte*BYTE_NUMBIT;
    return 1;
  }
  buffer->data[i] = data<<(BYTE_NUMBIT-numRemain);
  buffer->numBit = numBit;

  return 0;
}


/* BsGetBufferAppend() */
/* Append bits from bit stream to buffer. */
/* (Current position in bit stream is advanced !!!) */

int BsGetBufferAppend (
  BsBitStream *stream,		/* in: bit stream */
  BsBitBuffer *buffer,		/* out: buffer read */
				/*      (may be NULL if numBit==0) */
  int append,			/* in: if != 0: append bits to buffer */
				/*              (don't clear buffer) */
  long numBit)			/* in: num bits to read */
				/* returns: */
				/*  0=OK  1=error */
{
  long i,numByte,last_byte,numRemain;
  unsigned long data;
  int tmp,shift_cnt,eof;

  if (BSdebugLevel >= 2) {
    printf("BsGetBufferAppend: %s  id=%ld  numBit=%ld  ",
	   (stream->file!=NULL)?"file":"buffer",
	   stream->streamId,numBit);
    if (buffer != NULL)
      printf("bufSize=%ld  bufAddr=0x%lx  ",
	     buffer->size,(unsigned long)buffer);
    else
      printf("(bufAddr=(NULL)  ");
    printf("curBit=%ld\n",stream->currentBit);
  }

  if (stream->write != 0)
    CommonExit(1,"BsGetBufferAppend: stream not in read mode");

  if (stream->buffer[0] == buffer)
    CommonExit(1,"BsGetBufferAppend: cannot get buffer from itself");

  if (numBit < 0)
    CommonExit(1,"BsGetBufferAppend: number of bits out of range (%ld)",
	       numBit);

#if 1 	/* AI 990528 */    
  /* check whether number of bits to be read exceeds the end of bitstream */
  eof = BsEof(stream, numBit);
/*  if (BsEof(stream, numBit-1)) { */
  if (eof) {
    numBit = BYTE_NUMBIT*stream->numByte - stream->currentBit;
    if (BSdebugLevel >= 2) {
      printf("*** numBits(modified)=%ld\n", numBit);
    }
  }
#endif

  if (append) {

    /* append to buffer (don't clear buffer) */

    if ((numBit+buffer->numBit) > buffer->size)
      CommonExit(1,"BsGetBufferAppend: number of bits out of range (%ld)",
		 numBit);

    /* fill up the last possible incomplete byte */
    tmp = 8 - buffer->numBit%8;
    if (tmp == 8)
      tmp = 0;

    if (tmp <= numBit) {
      shift_cnt = 0;
    }
    else {
      shift_cnt = tmp - numBit;
      tmp = numBit;
    }

    if (tmp) {
      if (BsGetBit(stream,&data,tmp)) {
	CommonWarning("BsGetBufferAppend: error reading bit stream");
	return 1;
      }
      data <<= shift_cnt;
      numBit -= tmp;
      last_byte = buffer->numBit/8;
      data |= buffer->data[last_byte];
      buffer->numBit += tmp;
      buffer->data[last_byte] = data;
      last_byte++;
    }
    else
      last_byte = buffer->numBit/8;

  }
  else { /* if (append) */
    /* clear buffer */
    if (numBit > buffer->size)
      CommonExit(1,"BsGetBufferAppend: number of bits out of range (%ld)",
                 numBit);
    BsClearBuffer(buffer);
    last_byte = 0;
  }

  if (numBit > 0) {
    numByte = bit2byte(numBit)-1;
    for (i=last_byte; i<last_byte+numByte; i++) {
      if ((tmp = BsGetBit(stream,&data,BYTE_NUMBIT))) {
	buffer->numBit += (i-last_byte)*BYTE_NUMBIT;
        if (tmp==-1)
          return -1;	/* end of file */
	CommonWarning("BsGetBufferAppend: error reading bit stream");
	return 1;
      }
      buffer->data[i] = data;
    }
    numRemain = numBit-numByte*BYTE_NUMBIT;
    if (BsGetBit(stream,&data,numRemain)) {
      CommonWarning("BsGetBufferAppend: error reading bit stream");
      buffer->numBit += numByte*BYTE_NUMBIT;
      return 1;
    }
    buffer->data[i] = data<<(BYTE_NUMBIT-numRemain);
    buffer->numBit += numBit;
  }
#if 1	/* AI 990528 */
  if ( eof ) {
    /* just reached to the end of bitstream */
    if (stream->currentBit == BYTE_NUMBIT*stream->numByte) {
      if (BSdebugLevel >= 2) {
	printf("*** just reached the end of bitstream\n");
      }
      return -1;	/* end of file */
    }
  }
#endif
/*  } */
  return 0;
}

/* BsGetBufferAhead() */
/* Read bits ahead of current position from bit stream to buffer. */
/* (Current position in bit stream is NOT advanced !!!) */
/* (Buffer is cleared first - previous data in buffer is lost !!!) */

int BsGetBufferAhead (
  BsBitStream *stream,		/* in: bit stream */
  BsBitBuffer *buffer,		/* out: buffer read */
				/*      (may be NULL if numBit==0) */
  long numBit)			/* in: num bits to read */
				/* returns: */
				/*  0=OK  1=error */
{
  long oldCurrentBit;
  int result;

  if (BSdebugLevel >= 2)
    printf("BsGetBufferAhead: %s  id=%ld  numBit=%ld\n",
	   (stream->file!=NULL)?"file":"buffer",stream->streamId,numBit);

  if (numBit > stream->buffer[0]->size)
    CommonExit(1,"BsGetBufferAhead: "
	       "number of bits to look ahead too high (%ld)",numBit);

  oldCurrentBit = stream->currentBit;
  result = BsGetBuffer(stream,buffer,numBit);
  stream->currentBit = oldCurrentBit;
  if (result)
    if ( ! BSaacEOF || BSdebugLevel > 0  )
      CommonWarning("BsGetBufferAhead: error reading bit stream");

  return result;
}


/* BsGetSkip() */
/* Skip bits in bit stream (read). */
/* (Current position in bit stream is advanced !!!) */

int BsGetSkip (
  BsBitStream *stream,		/* in: bit stream */
  long numBit)			/* in: num bits to skip */
				/* returns: */
				/*  0=OK  1=error */
{
  if (BSdebugLevel >= 2) {
    printf("BsGetSkip: %s  id=%ld  numBit=%ld  ",
	   (stream->file!=NULL)?"file":"buffer",
	   stream->streamId,numBit);
    printf("curBit=%ld\n",stream->currentBit);
  }

  if (stream->write != 0)
    CommonExit(1,"BsGetSkip: stream not in read mode");
  if (numBit < 0)
    CommonExit(1,"BsGetSkip: number of bits out of range (%ld)",numBit);

  if (numBit == 0)
    return 0;

  if (BsReadAhead(stream,numBit) || BsCheckRead(stream,numBit)) {
    CommonWarning("BsGetSkip: error reading bit stream");
    return 1;
  }
  stream->currentBit += numBit;
  return 0;
}


/* BsPutBit() */
/* Write bits to bit stream. */

int BsPutBit (
  BsBitStream *stream,		/* in: bit stream */
  unsigned long data,		/* in: bits to write */
  int numBit)			/* in: num bits to write */
				/*     [0..32] */
				/* returns: */
				/*  0=OK  1=error */
{
  int num,maxNum,curNum;
  unsigned long bits;

  if (BSdebugLevel > 3)
    printf("BsPutBit: %s  id=%ld  numBit=%d  data=0x%lx,%ld  curBit=%ld\n",
	   (stream->file!=NULL)?"file":"buffer",
	   stream->streamId,numBit,data,data,stream->currentBit);

  if (stream->write != 1)
    CommonExit(1,"BsPutBit: stream not in write mode");
  if (numBit<0 || numBit>LONG_NUMBIT)
    CommonExit(1,"BsPutBit: number of bits out of range (%d)",numBit);
  if (numBit < 32 && data > ((unsigned long)1<<numBit)-1)
    CommonExit(1,"BsPutBit: data requires more than %d bits (0x%lx)",
	       numBit,data);

  if (numBit == 0)
    return 0;

  /* write bits in packets according to buffer byte boundaries */
  num = 0;
  maxNum = BYTE_NUMBIT - stream->currentBit % BYTE_NUMBIT;
  while (num < numBit) {
    curNum = min(numBit-num,maxNum);
    bits = data>>(numBit-num-curNum);
    if (BsWriteByte(stream,bits,curNum)) {
      CommonWarning("BsPutBit: error writing bit stream");
      return 1;
    }
    num += curNum;
    maxNum = BYTE_NUMBIT;
  }

  return 0;
}


/* BsPutBuffer() */
/* Write bits from buffer to bit stream. */

int BsPutBuffer (
  BsBitStream *stream,		/* in: bit stream */
  BsBitBuffer *buffer)		/* in: buffer to write */
				/* returns: */
				/*  0=OK  1=error */
{
  long i,numByte,numRemain;

  if (buffer->numBit == 0)
    return 0;

  if (BSdebugLevel >= 2)
    printf("BsPutBuffer: %s  id=%ld  numBit=%ld  bufAddr=0x%lx  curBit=%ld\n",
	   (stream->file!=NULL)?"file":"buffer",
	   stream->streamId,buffer->numBit,(unsigned long)buffer,
	   stream->currentBit);

  if (stream->write != 1)
    CommonExit(1,"BsPutBuffer: stream not in write mode");
  if (stream->buffer[0] == buffer)
    CommonExit(1,"BsPutBuffer: can not put buffer into itself");

  numByte = bit2byte(buffer->numBit)-1;
  for (i=0; i<numByte; i++)
    if (BsPutBit(stream,buffer->data[i],BYTE_NUMBIT)) {
      CommonWarning("BsPutBuffer: error writing bit stream");
      return 1;
    }
  numRemain = buffer->numBit-numByte*BYTE_NUMBIT;
  if (BsPutBit(stream,buffer->data[i]>>(BYTE_NUMBIT-numRemain),numRemain)) {
    CommonWarning("BsPutBuffer: error reading bit stream");
    return 1;
  }

  return 0;
}


/* BsAllocBuffer() */
/* Allocate bit buffer. */

BsBitBuffer *BsAllocBuffer (
  long numBit)			/* in: buffer size in bits */
				/* returns: */
				/*  bit buffer (handle) */
{
  BsBitBuffer *buffer;

  if (BSdebugLevel >= 2)
    printf("BsAllocBuffer: size=%ld\n",numBit);

  if ((buffer=(BsBitBuffer*)malloc(sizeof(BsBitBuffer))) == NULL)
    CommonExit(1,"BsAllocBuffer: memory allocation error (buffer)");
  if ((buffer->data=(unsigned char*)malloc(bit2byte(numBit)*sizeof(char)))
      == NULL)
    CommonExit(1,"BsAllocBuffer: memory allocation error (data)");
  buffer->numBit = 0;
  buffer->size = numBit;

  if (BSdebugLevel >= 2)
    printf("BsAllocBuffer: bufAddr=0x%lx\n",(unsigned long)buffer);

  return buffer;
}


/* BsFreeBuffer() */
/*FREE bit buffer. */

void BsFreeBuffer (
  BsBitBuffer *buffer)		/* in: bit buffer */
{
  if (BSdebugLevel >= 2)
    printf("BsFreeBuffer: size=%ld  bufAddr=0x%lx\n",
	   buffer->size,(unsigned long)buffer);

 FREE(buffer->data);
 FREE(buffer);
}


/* BsBufferNumBit() */
/* Get number of bits in buffer. */

long BsBufferNumBit (
  BsBitBuffer *buffer)		/* in: bit buffer */
				/* returns: */
				/*  number of bits in buffer */
{
  if (BSdebugLevel >= 2)
    printf("BsBufferNumBit: numBit=%ld  size=%ld  bufAddr=0x%lx\n",
	   buffer->numBit,buffer->size,(unsigned long)buffer);

  return buffer->numBit ;
}


/* BsClearBuffer() */
/* Clear bit buffer (set numBit to 0). */

void BsClearBuffer (
  BsBitBuffer *buffer)		/* in: bit buffer */
{
  if (BSdebugLevel >= 2)
    printf("BsClearBuffer: size=%ld  bufAddr=0x%lx\n",
	   buffer->size,(unsigned long)buffer);

  if (buffer->numBit != 0 ) {    
#if 0 /* removed due to BUG! in mp4dec.c */
    CommonWarning("BsClearBuffer: Buffer not empty!");    
#endif /* removed due to BUG! in mp4dec.c */
  }
  buffer->numBit = 0;
}




/* end of bitstream.c */