vpx/vp8/common/filter.c

/*
 *  Copyright (c) 2010 The WebM project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

#include <assert.h>
#include "./vp8_rtcd.h"
#include "vp8/common/filter.h"

DECLARE_ALIGNED(16, const short, vp8_bilinear_filters[8][2]) = {
  { 128, 0 }, { 112, 16 }, { 96, 32 }, { 80, 48 },
  { 64, 64 }, { 48, 80 },  { 32, 96 }, { 16, 112 }
};

DECLARE_ALIGNED(16, const short, vp8_sub_pel_filters[8][6]) = {

  { 0, 0, 128, 0, 0,
    0 }, /* note that 1/8 pel positions are just as per alpha -0.5 bicubic */
  { 0, -6, 123, 12, -1, 0 },
  { 2, -11, 108, 36, -8, 1 }, /* New 1/4 pel 6 tap filter */
  { 0, -9, 93, 50, -6, 0 },
  { 3, -16, 77, 77, -16, 3 }, /* New 1/2 pel 6 tap filter */
  { 0, -6, 50, 93, -9, 0 },
  { 1, -8, 36, 108, -11, 2 }, /* New 1/4 pel 6 tap filter */
  { 0, -1, 12, 123, -6, 0 },
};

static void filter_block2d_first_pass(unsigned char *src_ptr, int *output_ptr,
                                      unsigned int src_pixels_per_line,
                                      unsigned int pixel_step,
                                      unsigned int output_height,
                                      unsigned int output_width,
                                      const short *vp8_filter) {
  unsigned int i, j;
  int Temp;

  for (i = 0; i < output_height; ++i) {
    for (j = 0; j < output_width; ++j) {
      Temp = ((int)src_ptr[-2 * (int)pixel_step] * vp8_filter[0]) +
             ((int)src_ptr[-1 * (int)pixel_step] * vp8_filter[1]) +
             ((int)src_ptr[0] * vp8_filter[2]) +
             ((int)src_ptr[pixel_step] * vp8_filter[3]) +
             ((int)src_ptr[2 * pixel_step] * vp8_filter[4]) +
             ((int)src_ptr[3 * pixel_step] * vp8_filter[5]) +
             (VP8_FILTER_WEIGHT >> 1); /* Rounding */

      /* Normalize back to 0-255 */
      Temp = Temp >> VP8_FILTER_SHIFT;

      if (Temp < 0) {
        Temp = 0;
      } else if (Temp > 255) {
        Temp = 255;
      }

      output_ptr[j] = Temp;
      src_ptr++;
    }

    /* Next row... */
    src_ptr += src_pixels_per_line - output_width;
    output_ptr += output_width;
  }
}

static void filter_block2d_second_pass(int *src_ptr, unsigned char *output_ptr,
                                       int output_pitch,
                                       unsigned int src_pixels_per_line,
                                       unsigned int pixel_step,
                                       unsigned int output_height,
                                       unsigned int output_width,
                                       const short *vp8_filter) {
  unsigned int i, j;
  int Temp;

  for (i = 0; i < output_height; ++i) {
    for (j = 0; j < output_width; ++j) {
      /* Apply filter */
      Temp = ((int)src_ptr[-2 * (int)pixel_step] * vp8_filter[0]) +
             ((int)src_ptr[-1 * (int)pixel_step] * vp8_filter[1]) +
             ((int)src_ptr[0] * vp8_filter[2]) +
             ((int)src_ptr[pixel_step] * vp8_filter[3]) +
             ((int)src_ptr[2 * pixel_step] * vp8_filter[4]) +
             ((int)src_ptr[3 * pixel_step] * vp8_filter[5]) +
             (VP8_FILTER_WEIGHT >> 1); /* Rounding */

      /* Normalize back to 0-255 */
      Temp = Temp >> VP8_FILTER_SHIFT;

      if (Temp < 0) {
        Temp = 0;
      } else if (Temp > 255) {
        Temp = 255;
      }

      output_ptr[j] = (unsigned char)Temp;
      src_ptr++;
    }

    /* Start next row */
    src_ptr += src_pixels_per_line - output_width;
    output_ptr += output_pitch;
  }
}

static void filter_block2d(unsigned char *src_ptr, unsigned char *output_ptr,
                           unsigned int src_pixels_per_line, int output_pitch,
                           const short *HFilter, const short *VFilter) {
  int FData[9 * 4]; /* Temp data buffer used in filtering */

  /* First filter 1-D horizontally... */
  filter_block2d_first_pass(src_ptr - (2 * src_pixels_per_line), FData,
                            src_pixels_per_line, 1, 9, 4, HFilter);

  /* then filter verticaly... */
  filter_block2d_second_pass(FData + 8, output_ptr, output_pitch, 4, 4, 4, 4,
                             VFilter);
}

void vp8_sixtap_predict4x4_c(unsigned char *src_ptr, int src_pixels_per_line,
                             int xoffset, int yoffset, unsigned char *dst_ptr,
                             int dst_pitch) {
  const short *HFilter;
  const short *VFilter;

  HFilter = vp8_sub_pel_filters[xoffset]; /* 6 tap */
  VFilter = vp8_sub_pel_filters[yoffset]; /* 6 tap */

  filter_block2d(src_ptr, dst_ptr, src_pixels_per_line, dst_pitch, HFilter,
                 VFilter);
}
void vp8_sixtap_predict8x8_c(unsigned char *src_ptr, int src_pixels_per_line,
                             int xoffset, int yoffset, unsigned char *dst_ptr,
                             int dst_pitch) {
  const short *HFilter;
  const short *VFilter;
  int FData[13 * 16]; /* Temp data buffer used in filtering */

  HFilter = vp8_sub_pel_filters[xoffset]; /* 6 tap */
  VFilter = vp8_sub_pel_filters[yoffset]; /* 6 tap */

  /* First filter 1-D horizontally... */
  filter_block2d_first_pass(src_ptr - (2 * src_pixels_per_line), FData,
                            src_pixels_per_line, 1, 13, 8, HFilter);

  /* then filter verticaly... */
  filter_block2d_second_pass(FData + 16, dst_ptr, dst_pitch, 8, 8, 8, 8,
                             VFilter);
}

void vp8_sixtap_predict8x4_c(unsigned char *src_ptr, int src_pixels_per_line,
                             int xoffset, int yoffset, unsigned char *dst_ptr,
                             int dst_pitch) {
  const short *HFilter;
  const short *VFilter;
  int FData[13 * 16]; /* Temp data buffer used in filtering */

  HFilter = vp8_sub_pel_filters[xoffset]; /* 6 tap */
  VFilter = vp8_sub_pel_filters[yoffset]; /* 6 tap */

  /* First filter 1-D horizontally... */
  filter_block2d_first_pass(src_ptr - (2 * src_pixels_per_line), FData,
                            src_pixels_per_line, 1, 9, 8, HFilter);

  /* then filter verticaly... */
  filter_block2d_second_pass(FData + 16, dst_ptr, dst_pitch, 8, 8, 4, 8,
                             VFilter);
}

void vp8_sixtap_predict16x16_c(unsigned char *src_ptr, int src_pixels_per_line,
                               int xoffset, int yoffset, unsigned char *dst_ptr,
                               int dst_pitch) {
  const short *HFilter;
  const short *VFilter;
  int FData[21 * 24]; /* Temp data buffer used in filtering */

  HFilter = vp8_sub_pel_filters[xoffset]; /* 6 tap */
  VFilter = vp8_sub_pel_filters[yoffset]; /* 6 tap */

  /* First filter 1-D horizontally... */
  filter_block2d_first_pass(src_ptr - (2 * src_pixels_per_line), FData,
                            src_pixels_per_line, 1, 21, 16, HFilter);

  /* then filter verticaly... */
  filter_block2d_second_pass(FData + 32, dst_ptr, dst_pitch, 16, 16, 16, 16,
                             VFilter);
}

/****************************************************************************
 *
 *  ROUTINE       : filter_block2d_bil_first_pass
 *
 *  INPUTS        : UINT8  *src_ptr    : Pointer to source block.
 *                  UINT32  src_stride : Stride of source block.
 *                  UINT32  height     : Block height.
 *                  UINT32  width      : Block width.
 *                  INT32  *vp8_filter : Array of 2 bi-linear filter taps.
 *
 *  OUTPUTS       : INT32  *dst_ptr    : Pointer to filtered block.
 *
 *  RETURNS       : void
 *
 *  FUNCTION      : Applies a 1-D 2-tap bi-linear filter to the source block
 *                  in the horizontal direction to produce the filtered output
 *                  block. Used to implement first-pass of 2-D separable filter.
 *
 *  SPECIAL NOTES : Produces INT32 output to retain precision for next pass.
 *                  Two filter taps should sum to VP8_FILTER_WEIGHT.
 *
 ****************************************************************************/
static void filter_block2d_bil_first_pass(
    unsigned char *src_ptr, unsigned short *dst_ptr, unsigned int src_stride,
    unsigned int height, unsigned int width, const short *vp8_filter) {
  unsigned int i, j;

  for (i = 0; i < height; ++i) {
    for (j = 0; j < width; ++j) {
      /* Apply bilinear filter */
      dst_ptr[j] =
          (((int)src_ptr[0] * vp8_filter[0]) +
           ((int)src_ptr[1] * vp8_filter[1]) + (VP8_FILTER_WEIGHT / 2)) >>
          VP8_FILTER_SHIFT;
      src_ptr++;
    }

    /* Next row... */
    src_ptr += src_stride - width;
    dst_ptr += width;
  }
}

/****************************************************************************
 *
 *  ROUTINE       : filter_block2d_bil_second_pass
 *
 *  INPUTS        : INT32  *src_ptr    : Pointer to source block.
 *                  UINT32  dst_pitch  : Destination block pitch.
 *                  UINT32  height     : Block height.
 *                  UINT32  width      : Block width.
 *                  INT32  *vp8_filter : Array of 2 bi-linear filter taps.
 *
 *  OUTPUTS       : UINT16 *dst_ptr    : Pointer to filtered block.
 *
 *  RETURNS       : void
 *
 *  FUNCTION      : Applies a 1-D 2-tap bi-linear filter to the source block
 *                  in the vertical direction to produce the filtered output
 *                  block. Used to implement second-pass of 2-D separable
 *                  filter.
 *
 *  SPECIAL NOTES : Requires 32-bit input as produced by
 *                  filter_block2d_bil_first_pass.
 *                  Two filter taps should sum to VP8_FILTER_WEIGHT.
 *
 ****************************************************************************/
static void filter_block2d_bil_second_pass(unsigned short *src_ptr,
                                           unsigned char *dst_ptr,
                                           int dst_pitch, unsigned int height,
                                           unsigned int width,
                                           const short *vp8_filter) {
  unsigned int i, j;
  int Temp;

  for (i = 0; i < height; ++i) {
    for (j = 0; j < width; ++j) {
      /* Apply filter */
      Temp = ((int)src_ptr[0] * vp8_filter[0]) +
             ((int)src_ptr[width] * vp8_filter[1]) + (VP8_FILTER_WEIGHT / 2);
      dst_ptr[j] = (unsigned int)(Temp >> VP8_FILTER_SHIFT);
      src_ptr++;
    }

    /* Next row... */
    dst_ptr += dst_pitch;
  }
}

/****************************************************************************
 *
 *  ROUTINE       : filter_block2d_bil
 *
 *  INPUTS        : UINT8  *src_ptr          : Pointer to source block.
 *                  UINT32  src_pitch        : Stride of source block.
 *                  UINT32  dst_pitch        : Stride of destination block.
 *                  INT32  *HFilter          : Array of 2 horizontal filter
 *                                             taps.
 *                  INT32  *VFilter          : Array of 2 vertical filter taps.
 *                  INT32  Width             : Block width
 *                  INT32  Height            : Block height
 *
 *  OUTPUTS       : UINT16 *dst_ptr       : Pointer to filtered block.
 *
 *  RETURNS       : void
 *
 *  FUNCTION      : 2-D filters an input block by applying a 2-tap
 *                  bi-linear filter horizontally followed by a 2-tap
 *                  bi-linear filter vertically on the result.
 *
 *  SPECIAL NOTES : The largest block size can be handled here is 16x16
 *
 ****************************************************************************/
static void filter_block2d_bil(unsigned char *src_ptr, unsigned char *dst_ptr,
                               unsigned int src_pitch, unsigned int dst_pitch,
                               const short *HFilter, const short *VFilter,
                               int Width, int Height) {
  unsigned short FData[17 * 16]; /* Temp data buffer used in filtering */

  /* First filter 1-D horizontally... */
  filter_block2d_bil_first_pass(src_ptr, FData, src_pitch, Height + 1, Width,
                                HFilter);

  /* then 1-D vertically... */
  filter_block2d_bil_second_pass(FData, dst_ptr, dst_pitch, Height, Width,
                                 VFilter);
}

void vp8_bilinear_predict4x4_c(unsigned char *src_ptr, int src_pixels_per_line,
                               int xoffset, int yoffset, unsigned char *dst_ptr,
                               int dst_pitch) {
  const short *HFilter;
  const short *VFilter;

  // This represents a copy and is not required to be handled by optimizations.
  assert((xoffset | yoffset) != 0);

  HFilter = vp8_bilinear_filters[xoffset];
  VFilter = vp8_bilinear_filters[yoffset];
  filter_block2d_bil(src_ptr, dst_ptr, src_pixels_per_line, dst_pitch, HFilter,
                     VFilter, 4, 4);
}

void vp8_bilinear_predict8x8_c(unsigned char *src_ptr, int src_pixels_per_line,
                               int xoffset, int yoffset, unsigned char *dst_ptr,
                               int dst_pitch) {
  const short *HFilter;
  const short *VFilter;

  assert((xoffset | yoffset) != 0);

  HFilter = vp8_bilinear_filters[xoffset];
  VFilter = vp8_bilinear_filters[yoffset];

  filter_block2d_bil(src_ptr, dst_ptr, src_pixels_per_line, dst_pitch, HFilter,
                     VFilter, 8, 8);
}

void vp8_bilinear_predict8x4_c(unsigned char *src_ptr, int src_pixels_per_line,
                               int xoffset, int yoffset, unsigned char *dst_ptr,
                               int dst_pitch) {
  const short *HFilter;
  const short *VFilter;

  assert((xoffset | yoffset) != 0);

  HFilter = vp8_bilinear_filters[xoffset];
  VFilter = vp8_bilinear_filters[yoffset];

  filter_block2d_bil(src_ptr, dst_ptr, src_pixels_per_line, dst_pitch, HFilter,
                     VFilter, 8, 4);
}

void vp8_bilinear_predict16x16_c(unsigned char *src_ptr,
                                 int src_pixels_per_line, int xoffset,
                                 int yoffset, unsigned char *dst_ptr,
                                 int dst_pitch) {
  const short *HFilter;
  const short *VFilter;

  assert((xoffset | yoffset) != 0);

  HFilter = vp8_bilinear_filters[xoffset];
  VFilter = vp8_bilinear_filters[yoffset];

  filter_block2d_bil(src_ptr, dst_ptr, src_pixels_per_line, dst_pitch, HFilter,
                     VFilter, 16, 16);
}