bitbuffer.c

Nokia H.264/AVC Encoder/Decoder Usage Manual

/*
COPYRIGHT, LICENSE AND WARRANTY INFORMATION

This software module has been originally developed by Nokia Corporation. 

Provided that a person, entity or a company willing to use the Software 
(hereinafter Licensee) comply with all the terms and conditions of this 
Statement and subject to the limitations set forth in this Statement Nokia 
grants to such Licensee a non-exclusive, sub-licensable, worldwide, 
limited license under copyrights owned by Nokia to use the Software for 
the sole purpose of creating, manufacturing, selling, marketing, or  
distributing (including the right to make modifications to the Software) 
a fully compliant decoder implementation (hereinafter "Decoder") of 
ITU-T Recommendation H.264 / ISO/IEC International Standard 14496-10 and 
an encoder implementation producing output that is decodable with the 
Decoder.

Nokia retains the ownership of copyrights to the Software. There is no 
patent nor other intellectual property right of Nokia licensed under this 
Statement (except the copyright license above). Licensee hereby assumes 
sole responsibility to secure any other intellectual property rights 
needed, if any. For example, if patent licenses  are required, it is 
their responsibility to acquire the license before utilizing the Software.

The license by Nokia is subject to that the Licensee grants to Nokia the 
non-exclusive, worldwide, royalty-free, perpetual and irrevocable 
covenant that the Licensee(s) shall not bring a suit before any court or 
administrative agency or otherwise assert a claim for infringement under 
the Licensee intellectual property rights that, but for a license, would 
be infringed by the Software against  
   (a)  Nokia or Nokia's Affiliate; or  
   (b)  other recipient of a license and covenant not to sue with respect 
        to the Software from Nokia; or 
   (c)  contractor, customer or distributor of a party listed above in a 
        or b,  
which suit or claim is related to the Software or use thereof.

The Licensee(s) further agrees to grant a reciprocal license to Nokia 
(as granted by Nokia to the Licensee(s) on the modifications made by 
Licensee(s) to the Software. 

THE SOFTWARE IS PROVIDED "AS IS" AND THE ORIGINAL DEVELOPER DISCLAIMS 
ANY AND ALL WARRANTIES WHETHER EXPRESS, IMPLIED OR STATUTORY, INCLUDING 
BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS 
FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. THOSE INTENDING TO USE 
THE SOFTWARE ARE EXPRESSLY ADVISED THAT ITS USE MAY INFRINGE EXISTING 
PATENTS AND BE SUBJECT TO ROYALTY PAYMENTS TO PATENT OWNERS. ANYONE 
USING THE SOFTWARE ON THE BASIS OF THIS LICENSE AGREES TO OBTAIN THE 
NECESSARY PERMISSIONS FROM ANY AND ALL APPLICABLE PATENT OWNERS FOR SUCH 
USE.

IN NO EVENT SHALL THE ORIGINAL DEVELOPER BE LIABLE FOR ANY CLAIM, 
DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT 
OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE 
OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

This copyright, license and warranty information notice must be retained 
in all copies and derivative works of the Software or substantial 
portions thereof.
*/




#include <assert.h>
#include "debug.h"
#include "globals.h"
#include "bitbuffer.h"
#include "nccglob.h"


/* Maximum number of zeros in RBSP */
#define STR_MAX_ZEROS             2


/*
 *
 * bibOpen:
 *
 * Parameters:
 *      bitbuf                Bitbuffer object
 *
 * Function:
 *      Open and initialize bitbuffer writing
 *      The bits are written to a byte. When the byte is full, the byte is 
 *      stored in array.
 *
 * Returns:
 *      -
 *
 */
void bibOpen(bitbuffer_s *bitbuf, int initialSize)
{
  bitbuf->bufSize = initialSize;

  bitbuf->bufAddr = (u_int8 *) nccMalloc(bitbuf->bufSize);

  if (bitbuf->bufAddr == NULL) {
    deb0f(strerr, "Cannot allocate memory for bitbuffer");
    nccExit(1);
  }

  bibInit(bitbuf);
}


/*
 *
 * bibInit:
 *
 * Parameters:
 *      bitbuf                Bitbuffer object
 *
 * Function:
 *      Set the bit buffer in empty state.
 *
 * Returns:
 *      -
 *
 */
void bibInit(bitbuffer_s *bitbuf)
{
  bitbuf->bytePos = 0;
  bitbuf->currentBits = 0;
  bitbuf->bitpos = 32;
  bitbuf->numZeros = 0;
}


/*
 *
 * bibClose:
 *
 * Parameters:
 *      bitbuf                Bitbuffer object
 *
 * Function:
 *      Close bitbuffer
 *
 * Returns:
 *      -
 *
 */
void bibClose(bitbuffer_s *bitbuf)
{
  // release the buffer
  nccFree(bitbuf->bufAddr);
  bitbuf->bufAddr = 0;
}


/*
 *
 * bibPutByte:
 *
 * Parameters:
 *      bitbuf                Bitbuffer object
 *      byte                  Byte to store
 *
 * Function:
 *      Put one byte to the bitbuffer. If buffer is full, allocate 
 *      bigger buffer.
 *
 *      NOTE: does not insert start code emulation prevention bytes
 *
 * Returns:
 *      -
 */
void bibPutByte(bitbuffer_s *bitbuf, int byte)
{
  /* Check if we have enough memory and get more if not */
  if (bitbuf->bytePos == bitbuf->bufSize) {
    /* Increase buffer size by 20% and round up to nearest kilobyte */
    bitbuf->bufSize = (12*(bitbuf->bufSize)/10 + 1023) & ~1023;
    bitbuf->bufAddr = nccRealloc(bitbuf->bufAddr, bitbuf->bufSize);
    if (bitbuf->bufAddr == NULL) {
      deb0f(strerr, "Cannot allocate memory for bitbuffer");
      nccExit(1);
    }
  }

  /* Store byte into the bit buffer */
  bitbuf->bufAddr[bitbuf->bytePos++] = (u_int8)byte;
}


/*
 *
 * bibPutBits:
 *
 * Parameters:
 *      bitbuf                Bitbuffer object
 *      bits                  Bits to store
 *      len                   Number of bits to store
 *
 * Function:
 *      Put number of bits to bitbuffer. Also take care of start code
 *      emulation prevention.
 *
 * Returns:
 *      Number of bits stored
 */
int bibPutBits(bitbuffer_s *bitbuf, int bits, int len)
{
  /* To avoid the side affect of higher bits in the input byte */
  if (len != 32)
    bits &= ~((unsigned int)-1 << len);

  if (bitbuf->bitpos > len)
  {
    // make this path fast
    bitbuf->bitpos -= len;
    bitbuf->currentBits |= bits << bitbuf->bitpos;
  }
  else
  {
    int i, remLen;
    int currentByte;

    // fill the remaing bits in the buffer
    remLen = len - bitbuf->bitpos;
    bitbuf->currentBits |= bits >> remLen;

    // send 4 bytes
    for (i = 0; i < 4; i ++)
    {
      currentByte = bitbuf->currentBits >> 24;
      bitbuf->currentBits <<= 8;

      if (bitbuf->numZeros == STR_MAX_ZEROS  && (currentByte & 0xfc) == 0)
      {
        bibPutByte(bitbuf, 0x03);
        bitbuf->numZeros = 0;
      }

      if (currentByte == 0)
        bitbuf->numZeros ++;
      else
        bitbuf->numZeros = 0;

      bibPutByte(bitbuf, currentByte);
    }

    // put the remaining bits in the buffer
    bitbuf->bitpos = 32 - remLen;
    bitbuf->currentBits = 0;
    if (remLen)
      bitbuf->currentBits = bits << bitbuf->bitpos;
  }

  return len;
}


/*
 * bibByteAlign:
 *
 * Parameters:
 *      bitbuf                Bitbuffer object
 *
 * Function:
 *      Align bitbuffer writing at byte boundary.
 *
 * Returns:
 *      The number of skipped bits
 */
int bibByteAlign(bitbuffer_s *bitbuf)
{
  int bitsSkipped;

  while (bitbuf->bitpos < 32)
  {
    bibPutByte(bitbuf, bitbuf->currentBits >> 24);
    bitbuf->currentBits <<= 8;
    bitbuf->bitpos += 8;
  }

  bitsSkipped = bitbuf->bitpos - 32;
  bitbuf->bitpos = 32;

  // set numZeros to 0, because this function is called at the end of NAL
  bitbuf->numZeros = 0;

  return bitsSkipped;
}


/*
 * bibIsByteAlign:
 *
 * Parameters:
 *      bitbuf                Bitbuffer object
 *
 * Function:
 *      Check if the bitbuf is byte aligned.
 *
 * Returns:
 *      1: if byte aligned
 *      0: otherwise
 */
int bibIsByteAlign(bitbuffer_s *bitbuf)
{
  if (bitbuf->bitpos % 8 == 0)
    return 1;
  else
    return 0;
}




/*
 *
 * bibGetNumBits:
 *
 * Parameters:
 *      bitbuf                Bitbuffer object
 *
 * Function:
 *      Get bit buffer position in bits
 *
 * Returns:
 *      bit buffer position.
 *
 */
int bibGetNumBits(bitbuffer_s *bitbuf)
{
  return (bitbuf->bytePos * 8 + 32 - bitbuf->bitpos);
}


/*
 *
 * bibTrailingBits:
 *
 * Parameters:
 *      bitbuf                Bitbuffer object
 *
 * Function:
 *      Put bitbuffer trailing bits
 *
 * Returns:
 *      Number of bits stored
 *
 */
int bibTrailingBits(bitbuffer_s *bitbuf)
{
  int bits = 0;

  bits+=bibPutBits(bitbuf, 1, 1);         // rbsp_stop_one_bit  
  bits+=bibByteAlign(bitbuf);

  return bits;
}


/*
 *
 * bibGetBuffer:
 *
 * Parameters:
 *      bitbuf                Bitbuffer object
 *      bufferPtr             Return pointer for bit buffer
 *
 * Function:
 *      Get bit buffer pointer and size
 *
 * Returns:
 *      Number of bytes in bit buffer
 *
 */
int bibGetBuffer(bitbuffer_s *bitbuf, void **bufferPtr)
{
  *bufferPtr = bitbuf->bufAddr;

  return bitbuf->bytePos;
}