src/starboard/shared/starboard/player/filter/cpu_video_frame.cc

// Copyright 2017 The Cobalt Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "starboard/shared/starboard/player/filter/cpu_video_frame.h"

#include "starboard/common/log.h"
#include "starboard/memory.h"

namespace starboard {
namespace shared {
namespace starboard {
namespace player {
namespace filter {

namespace {

bool s_yuv_to_rgb_lookup_table_initialized = false;
int s_y_to_rgb[256];
int s_v_to_r[256];
int s_u_to_g[256];
int s_v_to_g[256];
int s_u_to_b[256];
uint8_t s_clamp_table[256 * 5];

void EnsureYUVToRGBLookupTableInitialized() {
  if (s_yuv_to_rgb_lookup_table_initialized) {
    return;
  }

  // The YUV to RGBA conversion is based on
  //   http://www.equasys.de/colorconversion.html.
  // The formula is:
  // r = 1.164f * y                      + 1.793f * (v - 128);
  // g = 1.164f * y - 0.213f * (u - 128) - 0.533f * (v - 128);
  // b = 1.164f * y + 2.112f * (u - 128);
  // And r/g/b has to be clamped to [0, 255].
  //
  // We optimize the conversion algorithm by creating two kinds of lookup
  // tables.  The color component table contains pre-calculated color component
  // values.  The clamp table contains a map between |v| + 512 to the clamped
  // |v| to avoid conditional operation.
  // The minimum value of |v| can be 2.112f * (-128) = -271, the maximum value
  // of |v| can be 1.164f * 255 + 2.112f * 127 = 565.  So we need 512 bytes at
  // each side of the clamp buffer.
  memset(s_clamp_table, 0, 512);
  memset(s_clamp_table + 768, 0xff, 512);

  uint8_t i = 0;
  while (true) {
    s_y_to_rgb[i] = static_cast<int>((i - 16) * 1.164f);
    s_v_to_r[i] = static_cast<int>((i - 128) * 1.793f);
    s_u_to_g[i] = static_cast<int>((i - 128) * -0.213f);
    s_v_to_g[i] = static_cast<int>((i - 128) * -0.533f);
    s_u_to_b[i] = static_cast<int>((i - 128) * 2.112f);
    s_clamp_table[512 + static_cast<std::size_t>(i)] = i;
    if (i == 255) {
      break;
    }
    ++i;
  }

  s_yuv_to_rgb_lookup_table_initialized = true;
}

uint8_t ClampColorComponent(int component) {
  return s_clamp_table[component + 512];
}

void CopyPlane(int bit_depth,
               uint8_t* destination,
               const uint8_t* source,
               int pixels) {
  if (bit_depth == 8) {
    memcpy(destination, source, pixels);
    return;
  }
  SB_DCHECK(bit_depth == 10 || bit_depth == 12);

  const int conversion_factor = 1 << (bit_depth - 8);

  const uint16_t* source_in_uint16 = reinterpret_cast<const uint16_t*>(source);
  while (pixels > 0) {
    *destination = static_cast<uint8_t>(*source_in_uint16 / conversion_factor);
    ++source_in_uint16;
    ++destination;
    --pixels;
  }
}

}  // namespace

int CpuVideoFrame::GetPlaneCount() const {
  SB_DCHECK(format_ != kInvalid);
  SB_DCHECK(format_ != kNativeTexture);

  return static_cast<int>(planes_.size());
}

const CpuVideoFrame::Plane& CpuVideoFrame::GetPlane(int index) const {
  SB_DCHECK(format_ != kInvalid);
  SB_DCHECK(format_ != kNativeTexture);
  SB_DCHECK(index >= 0 && index < GetPlaneCount())
      << "Invalid index: " << index;
  return planes_[index];
}

scoped_refptr<CpuVideoFrame> CpuVideoFrame::ConvertTo(
    Format target_format) const {
  SB_DCHECK(format_ == kYV12);
  SB_DCHECK(target_format == kBGRA32);

  EnsureYUVToRGBLookupTableInitialized();

  scoped_refptr<CpuVideoFrame> target_frame(new CpuVideoFrame(timestamp()));

  target_frame->format_ = target_format;
  target_frame->width_ = width();
  target_frame->height_ = height();
  target_frame->pixel_buffer_.reset(new uint8_t[width() * height() * 4]);
  target_frame->planes_.push_back(
      Plane(width(), height(), width() * 4, target_frame->pixel_buffer_.get()));

  const uint8_t* y_data = GetPlane(0).data;
  const uint8_t* u_data = GetPlane(1).data;
  const uint8_t* v_data = GetPlane(2).data;
  uint8_t* bgra_data = target_frame->pixel_buffer_.get();

  int height = this->height();
  int width = this->width();

  for (int row = 0; row < height; ++row) {
    const uint8_t* y = &y_data[row * GetPlane(0).pitch_in_bytes];
    const uint8_t* u = &u_data[row / 2 * GetPlane(1).pitch_in_bytes];
    const uint8_t* v = &v_data[row / 2 * GetPlane(2).pitch_in_bytes];
    int v_to_r = 0;
    int u_to_g = 0;
    int v_to_g = 0;
    int u_to_b = 0;

    for (int column = 0; column < width; ++column) {
      if (column % 2 == 0) {
        v_to_r = s_v_to_r[*v];
        u_to_g = s_u_to_g[*u];
        v_to_g = s_v_to_g[*v];
        u_to_b = s_u_to_b[*u];
      } else {
        ++u, ++v;
      }

      int y_to_rgb = s_y_to_rgb[*y];
      int r = y_to_rgb + v_to_r;
      int g = y_to_rgb + u_to_g + v_to_g;
      int b = y_to_rgb + u_to_b;

      *bgra_data++ = ClampColorComponent(b);
      *bgra_data++ = ClampColorComponent(g);
      *bgra_data++ = ClampColorComponent(r);
      *bgra_data++ = 0xff;

      ++y;
    }
  }

  return target_frame;
}

// static
scoped_refptr<CpuVideoFrame> CpuVideoFrame::CreateYV12Frame(
    int bit_depth,
    int width,
    int height,
    int source_pitch_in_bytes,
    SbTime timestamp,
    const uint8_t* y,
    const uint8_t* u,
    const uint8_t* v) {
  SB_DCHECK(bit_depth == 8 || bit_depth == 10 || bit_depth == 12);

  if (bit_depth > 8) {
    SB_DCHECK(source_pitch_in_bytes >= width * 2);
  } else {
    SB_DCHECK(source_pitch_in_bytes >= width);
  }

  scoped_refptr<CpuVideoFrame> frame(new CpuVideoFrame(timestamp));
  frame->format_ = kYV12;
  frame->width_ = width;
  frame->height_ = height;

  auto destination_pitch_in_bytes = source_pitch_in_bytes;
  if (bit_depth == 10 || bit_depth == 12) {
    // Reduce destination pitch to half as it will be converted into 8 bits.
    destination_pitch_in_bytes /= 2;
  }

  // U/V planes generally have half resolution of the Y plane.  However, in the
  // extreme case that any dimension of Y plane is odd, we want to have an
  // extra pixel on U/V planes.
  int uv_height = height / 2 + height % 2;
  int uv_width = width / 2 + width % 2;
  int uv_pitch_in_bytes =
      destination_pitch_in_bytes / 2 + destination_pitch_in_bytes % 2;

  int y_plane_size_in_bytes = height * destination_pitch_in_bytes;
  int uv_plane_size_in_bytes = uv_height * uv_pitch_in_bytes;
  frame->pixel_buffer_.reset(
      new uint8_t[y_plane_size_in_bytes + uv_plane_size_in_bytes * 2]);

  CopyPlane(bit_depth, frame->pixel_buffer_.get(), y, y_plane_size_in_bytes);
  CopyPlane(bit_depth, frame->pixel_buffer_.get() + y_plane_size_in_bytes, u,
            uv_plane_size_in_bytes);
  CopyPlane(bit_depth,
            frame->pixel_buffer_.get() + y_plane_size_in_bytes +
                uv_plane_size_in_bytes,
            v, uv_plane_size_in_bytes);

  frame->planes_.push_back(Plane(width, height, destination_pitch_in_bytes,
                                 frame->pixel_buffer_.get()));
  frame->planes_.push_back(
      Plane(uv_width, uv_height, uv_pitch_in_bytes,
            frame->pixel_buffer_.get() + y_plane_size_in_bytes));
  frame->planes_.push_back(Plane(uv_width, uv_height, uv_pitch_in_bytes,
                                 frame->pixel_buffer_.get() +
                                     y_plane_size_in_bytes +
                                     uv_plane_size_in_bytes));
  return frame;
}

}  // namespace filter
}  // namespace player
}  // namespace starboard
}  // namespace shared
}  // namespace starboard