ret = write(p_out, buf, (p->size_y_cr-crop_bottom-crop_top)*(p->size_x_cr-crop_right-crop_left)*symbol_size_in_bytes);
      if (ret != ((p->size_y_cr-crop_bottom-crop_top)*(p->size_x_cr-crop_right-crop_left)*symbol_size_in_bytes))
      {
        error ("write_out_picture: error writing to YUV output file.", 500);
      }
    }
  }

  free(buf);

//  fsync(p_out);
}

/*!
 ************************************************************************
 * \brief
 *    Initialize output buffer for direct output
 ************************************************************************
 */
void init_out_buffer()
{
  out_buffer = alloc_frame_store();
}

/*!
 ************************************************************************
 * \brief
 *    Uninitialize output buffer for direct output
 ************************************************************************
 */
void uninit_out_buffer()
{
  free_frame_store(out_buffer);
  out_buffer=NULL;
}

/*!
 ************************************************************************
 * \brief
 *    Initialize picture memory with (Y:0,U:128,V:128)
 ************************************************************************
 */
void clear_picture(StorablePicture *p)
{
  int i;

  if (img->bitdepth_luma == 8)
  {
    // this does not seem to be right since it seems to work only for imgpel == byte
    // should be fixed
    for(i=0;i<p->size_y;i++)
      memset(p->imgY[i], img->dc_pred_value_comp[0], p->size_x*sizeof(imgpel));
  }
  else
  {
    int j;
    for(i=0;i < p->size_y; i++)
    for(j=0;j < p->size_x; j++)
      p->imgY[i][j] = img->dc_pred_value_comp[0];
  }

  if (img->bitdepth_chroma == 8)
  {
    for(i=0;i<p->size_y_cr;i++)
      memset(p->imgUV[0][i], img->dc_pred_value_comp[1], p->size_x_cr*sizeof(imgpel));
    for(i=0;i<p->size_y_cr;i++)
      memset(p->imgUV[1][i], img->dc_pred_value_comp[2], p->size_x_cr*sizeof(imgpel));
  }
  else
  {  
   int k, j;
   for (k = 0; k < 2; k++)
   {
      for(i=0;i<p->size_y_cr;i++)
      for(j=0;j < p->size_x_cr; j++)
        p->imgUV[k][i][j] = img->dc_pred_value_comp[1];
   }
  }
}

/*!
 ************************************************************************
 * \brief
 *    Write out not paired direct output fields. A second empty field is generated
 *    and combined into the frame buffer.
 * \param fs
 *    FrameStore that contains a single field
 * \param p_out
 *    Output file
 ************************************************************************
 */
void write_unpaired_field(FrameStore* fs, int p_out)
{
  StorablePicture *p;
  assert (fs->is_used<3);
  if(fs->is_used &1)
  {
    // we have a top field
    // construct an empty bottom field
    p = fs->top_field;
    fs->bottom_field = alloc_storable_picture(BOTTOM_FIELD, p->size_x, p->size_y, p->size_x_cr, p->size_y_cr);
    fs->bottom_field->chroma_format_idc = p->chroma_format_idc;
    clear_picture(fs->bottom_field);
    dpb_combine_field_yuv(fs);
    write_picture (fs->frame, p_out, TOP_FIELD);
  }

  if(fs->is_used &2)
  {
    // we have a bottom field
    // construct an empty top field
    p = fs->bottom_field;
    fs->top_field = alloc_storable_picture(TOP_FIELD, p->size_x, p->size_y, p->size_x_cr, p->size_y_cr);
    clear_picture(fs->top_field);
    fs->top_field->chroma_format_idc = p->chroma_format_idc;
    clear_picture(fs->top_field);
    fs ->top_field->frame_cropping_flag = fs->bottom_field->frame_cropping_flag;
    if(fs ->top_field->frame_cropping_flag)
    {
      fs ->top_field->frame_cropping_rect_top_offset = fs->bottom_field->frame_cropping_rect_top_offset;
      fs ->top_field->frame_cropping_rect_bottom_offset = fs->bottom_field->frame_cropping_rect_bottom_offset;
      fs ->top_field->frame_cropping_rect_left_offset = fs->bottom_field->frame_cropping_rect_left_offset;
      fs ->top_field->frame_cropping_rect_right_offset = fs->bottom_field->frame_cropping_rect_right_offset;
    }
    dpb_combine_field_yuv(fs);
    write_picture (fs->frame, p_out, BOTTOM_FIELD);
  }

  fs->is_used=3;
}

/*!
 ************************************************************************
 * \brief
 *    Write out unpaired fields from output buffer.
 * \param p_out
 *    Output file
 ************************************************************************
 */
void flush_direct_output(int p_out)
{
  write_unpaired_field(out_buffer, p_out);

  free_storable_picture(out_buffer->frame);
  out_buffer->frame = NULL;
  free_storable_picture(out_buffer->top_field);
  out_buffer->top_field = NULL;
  free_storable_picture(out_buffer->bottom_field);
  out_buffer->bottom_field = NULL;
  out_buffer->is_used = 0;
}


/*!
 ************************************************************************
 * \brief
 *    Write a frame (from FrameStore)
 * \param fs
 *    FrameStore containing the frame
 * \param p_out
 *    Output file
 ************************************************************************
 */
void write_stored_frame( FrameStore *fs,int p_out)
{
  // make sure no direct output field is pending
  flush_direct_output(p_out);

  if (fs->is_used<3)
  {
    write_unpaired_field(fs, p_out);
  }
  else
  {
    write_picture(fs->frame, p_out, FRAME);
  }

  fs->is_output = 1;
}


/*!
 ************************************************************************
 * \brief
 *    Directly output a picture without storing it in the DPB. Fields
 *    are buffered before they are written to the file.
 * \param p
 *    Picture for output
 * \param p_out
 *    Output file
 ************************************************************************
 */
void direct_output(StorablePicture *p, int p_out)
{
  switch ( p->structure )
  {
  case FRAME:
    // we have a frame (or complementary field pair)
    // so output it directly
    flush_direct_output(p_out);
    write_picture (p, p_out, FRAME);
    free_storable_picture(p);
    return;
    break;
  case TOP_FIELD:
    if (out_buffer->is_used &1)
      flush_direct_output(p_out);
    out_buffer->top_field = p;
    out_buffer->is_used |= 1;
    break;
  case BOTTOM_FIELD:
    if (out_buffer->is_used &2)
      flush_direct_output(p_out);
    out_buffer->bottom_field = p;
    out_buffer->is_used |= 2;
    break;
  default:
    printf("invalid picture type\n");
    break;
  }

  if (out_buffer->is_used == 3)
  {
    // we have both fields, so output them
    dpb_combine_field_yuv(out_buffer);
    write_picture (out_buffer->frame, p_out, FRAME);
    free_storable_picture(out_buffer->frame);
    out_buffer->frame = NULL;
    free_storable_picture(out_buffer->top_field);
    out_buffer->top_field = NULL;
    free_storable_picture(out_buffer->bottom_field);
    out_buffer->bottom_field = NULL;
    out_buffer->is_used = 0;
  }
}


/*!
************************************************************************
* \brief
*    For adaptive frame/field coding remove dangling top field from direct
*    output frame version instead.
* \param p
*    Picture for output
* \param p_out
*    Output file
************************************************************************
*/
void direct_output_paff(StorablePicture *p, int p_out)
{
  printf("Warning!!! Frame can't fit in DPB. Displayed out of sequence.\n");
  free_storable_picture(out_buffer->frame);
  out_buffer->frame = NULL;
  free_storable_picture(out_buffer->top_field);
  out_buffer->top_field = NULL;
  free_storable_picture(out_buffer->bottom_field);
  out_buffer->bottom_field = NULL;
  out_buffer->is_used = 0;

  direct_output(p, p_out);
}