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src/Source/LibWebP/src/dec/dec.io.c  view on Meta::CPAN

  uint8_t* const u_dst = buf->u + (io->mb_y >> 1) * buf->u_stride;
  uint8_t* const v_dst = buf->v + (io->mb_y >> 1) * buf->v_stride;
  const int mb_w = io->mb_w;
  const int mb_h = io->mb_h;
  const int uv_w = (mb_w + 1) / 2;
  const int uv_h = (mb_h + 1) / 2;
  int j;
  for (j = 0; j < mb_h; ++j) {
    memcpy(y_dst + j * buf->y_stride, io->y + j * io->y_stride, mb_w);
  }
  for (j = 0; j < uv_h; ++j) {
    memcpy(u_dst + j * buf->u_stride, io->u + j * io->uv_stride, uv_w);
    memcpy(v_dst + j * buf->v_stride, io->v + j * io->uv_stride, uv_w);
  }
  return io->mb_h;
}

// Point-sampling U/V sampler.
static int EmitSampledRGB(const VP8Io* const io, WebPDecParams* const p) {
  WebPDecBuffer* const output = p->output;
  WebPRGBABuffer* const buf = &output->u.RGBA;
  uint8_t* const dst = buf->rgba + io->mb_y * buf->stride;
  WebPSamplerProcessPlane(io->y, io->y_stride,
                          io->u, io->v, io->uv_stride,
                          dst, buf->stride, io->mb_w, io->mb_h,
                          WebPSamplers[output->colorspace]);
  return io->mb_h;
}

//------------------------------------------------------------------------------
// YUV444 -> RGB conversion

#if 0   // TODO(skal): this is for future rescaling.
static int EmitRGB(const VP8Io* const io, WebPDecParams* const p) {
  WebPDecBuffer* output = p->output;
  const WebPRGBABuffer* const buf = &output->u.RGBA;
  uint8_t* dst = buf->rgba + io->mb_y * buf->stride;
  const uint8_t* y_src = io->y;
  const uint8_t* u_src = io->u;
  const uint8_t* v_src = io->v;
  const WebPYUV444Converter convert = WebPYUV444Converters[output->colorspace];
  const int mb_w = io->mb_w;
  const int last = io->mb_h;
  int j;
  for (j = 0; j < last; ++j) {
    convert(y_src, u_src, v_src, dst, mb_w);
    y_src += io->y_stride;
    u_src += io->uv_stride;
    v_src += io->uv_stride;
    dst += buf->stride;
  }
  return io->mb_h;
}
#endif

//------------------------------------------------------------------------------
// Fancy upsampling

#ifdef FANCY_UPSAMPLING
static int EmitFancyRGB(const VP8Io* const io, WebPDecParams* const p) {
  int num_lines_out = io->mb_h;   // a priori guess
  const WebPRGBABuffer* const buf = &p->output->u.RGBA;
  uint8_t* dst = buf->rgba + io->mb_y * buf->stride;
  WebPUpsampleLinePairFunc upsample = WebPUpsamplers[p->output->colorspace];
  const uint8_t* cur_y = io->y;
  const uint8_t* cur_u = io->u;
  const uint8_t* cur_v = io->v;
  const uint8_t* top_u = p->tmp_u;
  const uint8_t* top_v = p->tmp_v;
  int y = io->mb_y;
  const int y_end = io->mb_y + io->mb_h;
  const int mb_w = io->mb_w;
  const int uv_w = (mb_w + 1) / 2;

  if (y == 0) {
    // First line is special cased. We mirror the u/v samples at boundary.
    upsample(cur_y, NULL, cur_u, cur_v, cur_u, cur_v, dst, NULL, mb_w);
  } else {
    // We can finish the left-over line from previous call.
    upsample(p->tmp_y, cur_y, top_u, top_v, cur_u, cur_v,
             dst - buf->stride, dst, mb_w);
    ++num_lines_out;
  }
  // Loop over each output pairs of row.
  for (; y + 2 < y_end; y += 2) {
    top_u = cur_u;
    top_v = cur_v;
    cur_u += io->uv_stride;
    cur_v += io->uv_stride;
    dst += 2 * buf->stride;
    cur_y += 2 * io->y_stride;
    upsample(cur_y - io->y_stride, cur_y,
             top_u, top_v, cur_u, cur_v,
             dst - buf->stride, dst, mb_w);
  }
  // move to last row
  cur_y += io->y_stride;
  if (io->crop_top + y_end < io->crop_bottom) {
    // Save the unfinished samples for next call (as we're not done yet).
    memcpy(p->tmp_y, cur_y, mb_w * sizeof(*p->tmp_y));
    memcpy(p->tmp_u, cur_u, uv_w * sizeof(*p->tmp_u));
    memcpy(p->tmp_v, cur_v, uv_w * sizeof(*p->tmp_v));
    // The fancy upsampler leaves a row unfinished behind
    // (except for the very last row)
    num_lines_out--;
  } else {
    // Process the very last row of even-sized picture
    if (!(y_end & 1)) {
      upsample(cur_y, NULL, cur_u, cur_v, cur_u, cur_v,
               dst + buf->stride, NULL, mb_w);
    }
  }
  return num_lines_out;
}

#endif    /* FANCY_UPSAMPLING */

//------------------------------------------------------------------------------

static int EmitAlphaYUV(const VP8Io* const io, WebPDecParams* const p) {
  const uint8_t* alpha = io->a;