path: root/media/base/yuv_convert.cc

// Copyright (c) 2010 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// This webpage shows layout of YV12 and other YUV formats
// http://www.fourcc.org/yuv.php
// The actual conversion is best described here
// http://en.wikipedia.org/wiki/YUV
// An article on optimizing YUV conversion using tables instead of multiplies
// http://lestourtereaux.free.fr/papers/data/yuvrgb.pdf
//
// YV12 is a full plane of Y and a half height, half width chroma planes
// YV16 is a full plane of Y and a full height, half width chroma planes
//
// ARGB pixel format is output, which on little endian is stored as BGRA.
// The alpha is set to 255, allowing the application to use RGBA or RGB32.

#include "media/base/yuv_convert.h"

// Header for low level row functions.
#include "media/base/yuv_row.h"

#if USE_SSE
#if defined(_MSC_VER)
#include <intrin.h>
#else
#include <emmintrin.h>
#endif
#endif

namespace media {

// 16.16 fixed point arithmetic.
const int kFractionBits = 16;
const int kFractionMax = 1 << kFractionBits;

// Convert a frame of YUV to 32 bit ARGB.
void ConvertYUVToRGB32(const uint8* y_buf,
                       const uint8* u_buf,
                       const uint8* v_buf,
                       uint8* rgb_buf,
                       int width,
                       int height,
                       int y_pitch,
                       int uv_pitch,
                       int rgb_pitch,
                       YUVType yuv_type) {
  unsigned int y_shift = yuv_type;
  for (int y = 0; y < height; ++y) {
    uint8* rgb_row = rgb_buf + y * rgb_pitch;
    const uint8* y_ptr = y_buf + y * y_pitch;
    const uint8* u_ptr = u_buf + (y >> y_shift) * uv_pitch;
    const uint8* v_ptr = v_buf + (y >> y_shift) * uv_pitch;

    FastConvertYUVToRGB32Row(y_ptr,
                             u_ptr,
                             v_ptr,
                             rgb_row,
                             width);
  }

  // MMX used for FastConvertYUVToRGB32Row requires emms instruction.
  EMMS();
}

// FilterRows combines two rows of the image using linear interpolation.
// 4 pixels are blended at a time.
static void FilterRows(uint8* ybuf, const uint8* y0_ptr, const uint8* y1_ptr,
                       int width, int scaled_y_fraction) {
#if USE_SSE
  __m128i zero = _mm_setzero_si128();
  __m128i y1_fraction = _mm_set1_epi16(
      static_cast<unsigned short>(scaled_y_fraction >> 8));
  __m128i y0_fraction = _mm_set1_epi16(
      static_cast<unsigned short>((scaled_y_fraction >> 8) ^ 255));

  uint8* end = ybuf + width;
  if (ybuf < end) {
    do {
      __m128i y0 = _mm_loadl_epi64(reinterpret_cast<__m128i const*>(y0_ptr));
      __m128i y1 = _mm_loadl_epi64(reinterpret_cast<__m128i const*>(y1_ptr));
      y0 = _mm_unpacklo_epi8 (y0, zero);
      y1 = _mm_unpacklo_epi8 (y1, zero);
      y0 = _mm_mullo_epi16(y0, y0_fraction);
      y1 = _mm_mullo_epi16(y1, y1_fraction);
      y0 = _mm_add_epi16(y0, y1);  // 8.8 fixed point result
      y0 = _mm_srli_epi16(y0, 8);
      y0 = _mm_packus_epi16(y0, y0);
      _mm_storel_epi64(reinterpret_cast<__m128i *>(ybuf), y0);
      y0_ptr += 8;
      y1_ptr += 8;
      ybuf += 8;
    } while (ybuf < end);
  }
#else
  int y0_fraction = kFractionMax - 1 - scaled_y_fraction;
  int y1_fraction = scaled_y_fraction;
  uint8* end = ybuf + width;
  while (ybuf < end) {
    ybuf[0] = (y0_ptr[0] * (y0_fraction) +
               y1_ptr[0] * (y1_fraction)) >> kFractionBits;
    ybuf[1] = (y0_ptr[1] * (y0_fraction) +
               y1_ptr[1] * (y1_fraction)) >> kFractionBits;
    ybuf[2] = (y0_ptr[2] * (y0_fraction) +
               y1_ptr[2] * (y1_fraction)) >> kFractionBits;
    ybuf[3] = (y0_ptr[3] * (y0_fraction) +
               y1_ptr[3] * (y1_fraction)) >> kFractionBits;
    y0_ptr += 4;
    y1_ptr += 4;
    ybuf += 4;
  }
#endif

  // Value at |ybuf[width]| must be the same as at |ybuf[width-1]|.
  if (width > 1) {
    end[0] = end[-1];
  }
}

// Scale a frame of YUV to 32 bit ARGB.
void ScaleYUVToRGB32(const uint8* y_buf,
                     const uint8* u_buf,
                     const uint8* v_buf,
                     uint8* rgb_buf,
                     int width,
                     int height,
                     int scaled_width,
                     int scaled_height,
                     int y_pitch,
                     int uv_pitch,
                     int rgb_pitch,
                     YUVType yuv_type,
                     Rotate view_rotate,
                     ScaleFilter filter) {
  const int kFilterBufferSize = 8192;
  // Disable filtering if the screen is too big (to avoid buffer overflows).
  // This should never happen to regular users: they don't have monitors
  // wider than 8192 pixels.
  if (width > kFilterBufferSize)
    filter = FILTER_NONE;

  unsigned int y_shift = yuv_type;
  // Diagram showing origin and direction of source sampling.
  // ->0   4<-
  // 7       3
  //
  // 6       5
  // ->1   2<-
  // Rotations that start at right side of image.
  if ((view_rotate == ROTATE_180) ||
      (view_rotate == ROTATE_270) ||
      (view_rotate == MIRROR_ROTATE_0) ||
      (view_rotate == MIRROR_ROTATE_90)) {
    y_buf += width - 1;
    u_buf += width / 2 - 1;
    v_buf += width / 2 - 1;
    width = -width;
  }
  // Rotations that start at bottom of image.
  if ((view_rotate == ROTATE_90) ||
      (view_rotate == ROTATE_180) ||
      (view_rotate == MIRROR_ROTATE_90) ||
      (view_rotate == MIRROR_ROTATE_180)) {
    y_buf += (height - 1) * y_pitch;
    u_buf += ((height >> y_shift) - 1) * uv_pitch;
    v_buf += ((height >> y_shift) - 1) * uv_pitch;
    height = -height;
  }

  // Handle zero sized destination.
  if (scaled_width == 0 || scaled_height == 0)
    return;
  int scaled_dx = width * kFractionMax / scaled_width;
  int scaled_dy = height * kFractionMax / scaled_height;

  int scaled_dx_uv = scaled_dx;

  if ((view_rotate == ROTATE_90) ||
      (view_rotate == ROTATE_270)) {
    int tmp = scaled_height;
    scaled_height = scaled_width;
    scaled_width = tmp;
    tmp = height;
    height = width;
    width = tmp;
    int original_dx = scaled_dx;
    int original_dy = scaled_dy;
    scaled_dx = ((original_dy >> kFractionBits) * y_pitch) << kFractionBits;
    scaled_dx_uv = ((original_dy >> kFractionBits) * uv_pitch) << kFractionBits;
    scaled_dy = original_dx;
    if (view_rotate == ROTATE_90) {
      y_pitch = -1;
      uv_pitch = -1;
      height = -height;
    } else {
      y_pitch = 1;
      uv_pitch = 1;
    }
  }

  // Need padding in the end because FilterRows() may override up to 7
  // pixels after the end.
  uint8 ybuf[kFilterBufferSize + 16];
  uint8 ubuf[kFilterBufferSize / 2 + 16];
  uint8 vbuf[kFilterBufferSize / 2 + 16];
  int yscale_fixed = (height << kFractionBits) / scaled_height;
  for (int y = 0; y < scaled_height; ++y) {
    uint8* dest_pixel = rgb_buf + y * rgb_pitch;
    int scaled_y = (y * yscale_fixed);

    const uint8* y0_ptr = y_buf + (scaled_y >> kFractionBits) * y_pitch;
    const uint8* y1_ptr = y0_ptr + y_pitch;

    const uint8* u0_ptr = u_buf +
        ((scaled_y >> kFractionBits) >> y_shift) * uv_pitch;
    const uint8* u1_ptr = u0_ptr + uv_pitch;
    const uint8* v0_ptr = v_buf +
        ((scaled_y >> kFractionBits) >> y_shift) * uv_pitch;
    const uint8* v1_ptr = v0_ptr + uv_pitch;

    int scaled_y_fraction = scaled_y & (kFractionMax - 1);
    int scaled_uv_fraction = (scaled_y >> y_shift) & (kFractionMax - 1);

    const uint8* y_ptr = y0_ptr;
    const uint8* u_ptr = u0_ptr;
    const uint8* v_ptr = v0_ptr;
    // TODO(sergeyu): Avoid filtering when fraction is 0.
    if (filter == media::FILTER_BILINEAR && y + 1 < scaled_height) {
      FilterRows(ybuf, y0_ptr, y1_ptr, width, scaled_y_fraction);
      y_ptr = ybuf;

      if ((y >> y_shift) + 1 < scaled_height >> y_shift) {
        FilterRows(ubuf, u0_ptr, u1_ptr, width / 2, scaled_uv_fraction);
        u_ptr = ubuf;
        FilterRows(vbuf, v0_ptr, v1_ptr, width / 2, scaled_uv_fraction);
        v_ptr = vbuf;
      }
    }
    if (scaled_dx == kFractionMax) {  // Not scaled
      FastConvertYUVToRGB32Row(y_ptr, u_ptr, v_ptr,
                               dest_pixel, scaled_width);
    } else {
      if (filter == FILTER_BILINEAR)
        LinearScaleYUVToRGB32Row(y_ptr, u_ptr, v_ptr,
                                 dest_pixel, scaled_width, scaled_dx);
      else
        ScaleYUVToRGB32Row(y_ptr, u_ptr, v_ptr,
                           dest_pixel, scaled_width, scaled_dx);
    }
  }

  // MMX used for FastConvertYUVToRGB32Row requires emms instruction.
  EMMS();
}

}  // namespace media