media/filters/vp8_parser.h

   1 // Copyright 2015 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4 //
   5 // This file contains an implementation of a VP8 raw stream parser,
   6 // as defined in RFC 6386.
   7
   8 #ifndef MEDIA_FILTERS_VP8_PARSER_H_
   9 #define MEDIA_FILTERS_VP8_PARSER_H_
  10
  11 #include "media/base/media_export.h"
  12 #include "media/filters/vp8_bool_decoder.h"
  13
  14 namespace media {
  15
  16 // See spec for definitions of values/fields.
  17 const size_t kMaxMBSegments = 4;
  18 const size_t kNumMBFeatureTreeProbs = 3;
  19
  20 // Member of Vp8FrameHeader and will be 0-initialized
  21 // in Vp8FrameHeader's constructor.
  22 struct MEDIA_EXPORT Vp8SegmentationHeader {
  23   enum SegmentFeatureMode { FEATURE_MODE_DELTA = 0, FEATURE_MODE_ABSOLUTE = 1 };
  24
  25   bool segmentation_enabled;
  26   bool update_mb_segmentation_map;
  27   bool update_segment_feature_data;
  28   SegmentFeatureMode segment_feature_mode;
  29
  30   int8_t quantizer_update_value[kMaxMBSegments];
  31   int8_t lf_update_value[kMaxMBSegments];
  32   static const int kDefaultSegmentProb = 255;
  33   uint8_t segment_prob[kNumMBFeatureTreeProbs];
  34 };
  35
  36 const size_t kNumBlockContexts = 4;
  37
  38 // Member of Vp8FrameHeader and will be 0-initialized
  39 // in Vp8FrameHeader's constructor.
  40 struct MEDIA_EXPORT Vp8LoopFilterHeader {
  41   enum Type { LOOP_FILTER_TYPE_NORMAL = 0, LOOP_FILTER_TYPE_SIMPLE = 1 };
  42   Type type;
  43   uint8_t level;
  44   uint8_t sharpness_level;
  45   bool loop_filter_adj_enable;
  46   bool mode_ref_lf_delta_update;
  47
  48   int8_t ref_frame_delta[kNumBlockContexts];
  49   int8_t mb_mode_delta[kNumBlockContexts];
  50 };
  51
  52 // Member of Vp8FrameHeader and will be 0-initialized
  53 // in Vp8FrameHeader's constructor.
  54 struct MEDIA_EXPORT Vp8QuantizationHeader {
  55   uint8_t y_ac_qi;
  56   int8_t y_dc_delta;
  57   int8_t y2_dc_delta;
  58   int8_t y2_ac_delta;
  59   int8_t uv_dc_delta;
  60   int8_t uv_ac_delta;
  61 };
  62
  63 const size_t kNumBlockTypes = 4;
  64 const size_t kNumCoeffBands = 8;
  65 const size_t kNumPrevCoeffContexts = 3;
  66 const size_t kNumEntropyNodes = 11;
  67
  68 const size_t kNumMVContexts = 2;
  69 const size_t kNumMVProbs = 19;
  70
  71 const size_t kNumYModeProbs = 4;
  72 const size_t kNumUVModeProbs = 3;
  73
  74 // Member of Vp8FrameHeader and will be 0-initialized
  75 // in Vp8FrameHeader's constructor.
  76 struct Vp8EntropyHeader {
  77   uint8_t coeff_probs[kNumBlockTypes][kNumCoeffBands][kNumPrevCoeffContexts]
  78                      [kNumEntropyNodes];
  79
  80   uint8_t y_mode_probs[kNumYModeProbs];
  81   uint8_t uv_mode_probs[kNumUVModeProbs];
  82
  83   uint8_t mv_probs[kNumMVContexts][kNumMVProbs];
  84 };
  85
  86 const size_t kMaxDCTPartitions = 8;
  87
  88 struct MEDIA_EXPORT Vp8FrameHeader {
  89   Vp8FrameHeader();
  90
  91   enum FrameType { KEYFRAME = 0, INTERFRAME = 1 };
  92   bool IsKeyframe() const { return key_frame == KEYFRAME; }
  93
  94   enum GoldenRefreshMode {
  95     COPY_LAST_TO_GOLDEN = 1,
  96     COPY_ALT_TO_GOLDEN = 2,
  97   };
  98
  99   enum AltRefreshMode {
 100     COPY_LAST_TO_ALT = 1,
 101     COPY_GOLDEN_TO_ALT = 2,
 102   };
 103
 104   FrameType key_frame;
 105   uint8_t version;
 106   bool is_experimental;
 107   bool show_frame;
 108   size_t first_part_size;
 109
 110   uint16_t width;
 111   uint8_t horizontal_scale;
 112   uint16_t height;
 113   uint8_t vertical_scale;
 114
 115   Vp8SegmentationHeader segmentation_hdr;
 116   Vp8LoopFilterHeader loopfilter_hdr;
 117   Vp8QuantizationHeader quantization_hdr;
 118
 119   size_t num_of_dct_partitions;
 120
 121   Vp8EntropyHeader entropy_hdr;
 122
 123   bool refresh_entropy_probs;
 124   bool refresh_golden_frame;
 125   bool refresh_alternate_frame;
 126   GoldenRefreshMode copy_buffer_to_golden;
 127   AltRefreshMode copy_buffer_to_alternate;
 128   uint8_t sign_bias_golden;
 129   uint8_t sign_bias_alternate;
 130   bool refresh_last;
 131
 132   bool mb_no_skip_coeff;
 133   uint8_t prob_skip_false;
 134   uint8_t prob_intra;
 135   uint8_t prob_last;
 136   uint8_t prob_gf;
 137
 138   const uint8_t* data;
 139   size_t frame_size;
 140
 141   size_t dct_partition_sizes[kMaxDCTPartitions];
 142   // Offset in bytes from data.
 143   off_t first_part_offset;
 144   // Offset in bits from first_part_offset.
 145   off_t macroblock_bit_offset;
 146
 147   // Bool decoder state
 148   uint8_t bool_dec_range;
 149   uint8_t bool_dec_value;
 150   uint8_t bool_dec_count;
 151 };
 152
 153 // A parser for raw VP8 streams as specified in RFC 6386.
 154 class MEDIA_EXPORT Vp8Parser {
 155  public:
 156   Vp8Parser();
 157   ~Vp8Parser();
 158
 159   // Try to parse exactly one VP8 frame starting at |ptr| and of size |size|,
 160   // filling the parsed data in |fhdr|. Return true on success.
 161   // Size has to be exactly the size of the frame and coming from the caller,
 162   // who needs to acquire it from elsewhere (normally from a container).
 163   bool ParseFrame(const uint8_t* ptr, size_t size, Vp8FrameHeader* fhdr);
 164
 165  private:
 166   bool ParseFrameTag(Vp8FrameHeader* fhdr);
 167   bool ParseFrameHeader(Vp8FrameHeader* fhdr);
 168
 169   bool ParseSegmentationHeader(bool keyframe);
 170   bool ParseLoopFilterHeader(bool keyframe);
 171   bool ParseQuantizationHeader(Vp8QuantizationHeader* qhdr);
 172   bool ParseTokenProbs(Vp8EntropyHeader* ehdr, bool update_curr_probs);
 173   bool ParseIntraProbs(Vp8EntropyHeader* ehdr, bool update_curr_probs);
 174   bool ParseMVProbs(Vp8EntropyHeader* ehdr, bool update_curr_probs);
 175   bool ParsePartitions(Vp8FrameHeader* fhdr);
 176   void ResetProbs(Vp8EntropyHeader* ehdr);
 177
 178   // These persist across calls to ParseFrame() and may be used and/or updated
 179   // for subsequent frames if the stream instructs us to do so.
 180   Vp8SegmentationHeader curr_segmentation_hdr_;
 181   Vp8LoopFilterHeader curr_loopfilter_hdr_;
 182   Vp8EntropyHeader curr_entropy_hdr_;
 183
 184   const uint8_t* stream_;
 185   size_t bytes_left_;
 186   Vp8BoolDecoder bd_;
 187
 188   DISALLOW_COPY_AND_ASSIGN(Vp8Parser);
 189 };
 190
 191 }  // namespace media
 192
 193 #endif  // MEDIA_FILTERS_VP8_PARSER_H_