media/filters/vp9_parser.h

// Copyright 2015 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 file contains an implementation of a VP9 bitstream parser. The main
// purpose of this parser is to support hardware decode acceleration. Some
// accelerators, e.g. libva which implements VA-API, require the caller
// (chrome) to feed them parsed VP9 frame header.
//
// See media::VP9Decoder for example usage.
//
#ifndef MEDIA_FILTERS_VP9_PARSER_H_
#define MEDIA_FILTERS_VP9_PARSER_H_

#include <stddef.h>
#include <stdint.h>
#include <sys/types.h>

#include <deque>

#include "base/macros.h"
#include "media/base/media_export.h"
#include "media/filters/vp9_raw_bits_reader.h"

namespace media {

const int kVp9MaxProfile = 4;
const int kVp9NumRefFramesLog2 = 3;
const size_t kVp9NumRefFrames = 1 << kVp9NumRefFramesLog2;
const uint8_t kVp9MaxProb = 255;
const size_t kVp9NumRefsPerFrame = 3;

enum class Vp9ColorSpace {
  UNKNOWN = 0,
  BT_601 = 1,
  BT_709 = 2,
  SMPTE_170 = 3,
  SMPTE_240 = 4,
  BT_2020 = 5,
  RESERVED = 6,
  SRGB = 7,
};

enum Vp9InterpFilter {
  EIGHTTAP = 0,
  EIGHTTAP_SMOOTH = 1,
  EIGHTTAP_SHARP = 2,
  BILINEAR = 3,
  SWICHABLE = 4,
};

struct MEDIA_EXPORT Vp9Segmentation {
  static const size_t kNumSegments = 8;
  static const size_t kNumTreeProbs = kNumSegments - 1;
  static const size_t kNumPredictionProbs = 3;
  enum SegmentLevelFeature {
    SEG_LVL_ALT_Q = 0,
    SEG_LVL_ALT_LF = 1,
    SEG_LVL_REF_FRAME = 2,
    SEG_LVL_SKIP = 3,
    SEG_LVL_MAX
  };

  bool enabled;

  bool update_map;
  uint8_t tree_probs[kNumTreeProbs];
  bool temporal_update;
  uint8_t pred_probs[kNumPredictionProbs];

  bool update_data;
  bool abs_delta;
  bool feature_enabled[kNumSegments][SEG_LVL_MAX];
  int16_t feature_data[kNumSegments][SEG_LVL_MAX];

  int16_t y_dequant[kNumSegments][2];
  int16_t uv_dequant[kNumSegments][2];

  bool FeatureEnabled(size_t seg_id, SegmentLevelFeature feature) const {
    return feature_enabled[seg_id][feature];
  }

  int16_t FeatureData(size_t seg_id, SegmentLevelFeature feature) const {
    return feature_data[seg_id][feature];
  }
};

struct MEDIA_EXPORT Vp9LoopFilter {
  enum Vp9FrameType {
    VP9_FRAME_INTRA = 0,
    VP9_FRAME_LAST = 1,
    VP9_FRAME_GOLDEN = 2,
    VP9_FRAME_ALTREF = 3,
    VP9_FRAME_MAX = 4,
  };

  static const size_t kNumModeDeltas = 2;

  uint8_t filter_level;
  uint8_t sharpness_level;

  bool mode_ref_delta_enabled;
  bool mode_ref_delta_update;
  bool update_ref_deltas[VP9_FRAME_MAX];
  int8_t ref_deltas[VP9_FRAME_MAX];
  bool update_mode_deltas[kNumModeDeltas];
  int8_t mode_deltas[kNumModeDeltas];

  uint8_t lvl[Vp9Segmentation::kNumSegments][VP9_FRAME_MAX][kNumModeDeltas];
};

// Members of Vp9FrameHeader will be 0-initialized by Vp9Parser::ParseNextFrame.
struct MEDIA_EXPORT Vp9QuantizationParams {
  bool IsLossless() const {
    return base_qindex == 0 && y_dc_delta == 0 && uv_dc_delta == 0 &&
           uv_ac_delta == 0;
  }

  uint8_t base_qindex;
  int8_t y_dc_delta;
  int8_t uv_dc_delta;
  int8_t uv_ac_delta;
};

// VP9 frame header.
struct MEDIA_EXPORT Vp9FrameHeader {
  enum FrameType {
    KEYFRAME = 0,
    INTERFRAME = 1,
  };

  bool IsKeyframe() const;
  bool RefreshFlag(size_t i) const { return !!(refresh_flags & (1u << i)); }

  uint8_t profile;

  bool show_existing_frame;
  uint8_t frame_to_show;

  FrameType frame_type;

  bool show_frame;
  bool error_resilient_mode;

  uint8_t bit_depth;
  Vp9ColorSpace color_space;
  bool yuv_range;
  uint8_t subsampling_x;
  uint8_t subsampling_y;

  // The range of width and height is 1..2^16.
  uint32_t width;
  uint32_t height;
  uint32_t display_width;
  uint32_t display_height;

  bool intra_only;
  uint8_t reset_context;
  uint8_t refresh_flags;
  uint8_t frame_refs[kVp9NumRefsPerFrame];
  bool ref_sign_biases[kVp9NumRefsPerFrame];
  bool allow_high_precision_mv;
  Vp9InterpFilter interp_filter;

  bool refresh_frame_context;
  bool frame_parallel_decoding_mode;
  uint8_t frame_context_idx;

  Vp9QuantizationParams quant_params;

  uint8_t log2_tile_cols;
  uint8_t log2_tile_rows;

  // Pointer to the beginning of frame data. It is a responsibility of the
  // client of the Vp9Parser to maintain validity of this data while it is
  // being used outside of that class.
  const uint8_t* data;

  // Size of |data| in bytes.
  size_t frame_size;

  // Size of compressed header in bytes.
  size_t first_partition_size;

  // Size of uncompressed header in bytes.
  size_t uncompressed_header_size;
};

// A parser for VP9 bitstream.
class MEDIA_EXPORT Vp9Parser {
 public:
  // ParseNextFrame() return values. See documentation for ParseNextFrame().
  enum Result {
    kOk,
    kInvalidStream,
    kEOStream,
  };

  Vp9Parser();
  ~Vp9Parser();

  // Set a new stream buffer to read from, starting at |stream| and of size
  // |stream_size| in bytes. |stream| must point to the beginning of a single
  // frame or a single superframe, is owned by caller and must remain valid
  // until the next call to SetStream().
  void SetStream(const uint8_t* stream, off_t stream_size);

  // Parse the next frame in the current stream buffer, filling |fhdr| with
  // the parsed frame header and updating current segmentation and loop filter
  // state. Return kOk if a frame has successfully been parsed, kEOStream if
  // there is no more data in the current stream buffer, or kInvalidStream
  // on error.
  Result ParseNextFrame(Vp9FrameHeader* fhdr);

  // Return current segmentation state.
  const Vp9Segmentation& GetSegmentation() const { return segmentation_; }

  // Return current loop filter state.
  const Vp9LoopFilter& GetLoopFilter() const { return loop_filter_; }

  // Clear parser state and return to an initialized state.
  void Reset();

 private:
  // The parsing context to keep track of references.
  struct ReferenceSlot {
    uint32_t width;
    uint32_t height;
  };

  bool ParseSuperframe();
  uint8_t ReadProfile();
  bool VerifySyncCode();
  bool ReadBitDepthColorSpaceSampling(Vp9FrameHeader* fhdr);
  void ReadFrameSize(Vp9FrameHeader* fhdr);
  bool ReadFrameSizeFromRefs(Vp9FrameHeader* fhdr);
  void ReadDisplayFrameSize(Vp9FrameHeader* fhdr);
  Vp9InterpFilter ReadInterpFilter();
  void ReadLoopFilter();
  void ReadQuantization(Vp9QuantizationParams* quants);
  void ReadSegmentationMap();
  void ReadSegmentationData();
  void ReadSegmentation();
  void ReadTiles(Vp9FrameHeader* fhdr);
  bool ParseUncompressedHeader(const uint8_t* stream,
                               off_t frame_size,
                               Vp9FrameHeader* fhdr);
  void UpdateSlots(const Vp9FrameHeader* fhdr);

  void ResetLoopfilter();
  void SetupPastIndependence();
  size_t GetQIndex(const Vp9QuantizationParams& quant, size_t segid) const;
  void SetupSegmentationDequant(const Vp9QuantizationParams& quant);
  void SetupLoopFilter();

  // Current address in the bitstream buffer.
  const uint8_t* stream_;

  // Remaining bytes in stream_.
  off_t bytes_left_;

  // Stores start pointer and size of each frame within the current superframe.
  struct FrameInfo {
    FrameInfo(const uint8_t* ptr, off_t size);

    // Starting address of the frame.
    const uint8_t* ptr;

    // Size of the frame in bytes.
    off_t size;
  };

  // FrameInfo for the remaining frames in the current superframe to be parsed.
  std::deque<FrameInfo> frames_;

  // Raw bits decoder for uncompressed frame header.
  Vp9RawBitsReader reader_;

  // Segmentation and loop filter state that persists across frames.
  Vp9Segmentation segmentation_;
  Vp9LoopFilter loop_filter_;

  // The parsing context to keep track of references.
  ReferenceSlot ref_slots_[kVp9NumRefFrames];

  DISALLOW_COPY_AND_ASSIGN(Vp9Parser);
};

}  // namespace media

#endif  // MEDIA_FILTERS_VP9_PARSER_H_