third_party/libwebp/webp/format_constants.h

   1 // Copyright 2012 Google Inc. All Rights Reserved.
   2 //
   3 // Use of this source code is governed by a BSD-style license
   4 // that can be found in the COPYING file in the root of the source
   5 // tree. An additional intellectual property rights grant can be found
   6 // in the file PATENTS. All contributing project authors may
   7 // be found in the AUTHORS file in the root of the source tree.
   8 // -----------------------------------------------------------------------------
   9 //
  10 //  Internal header for constants related to WebP file format.
  11 //
  12 // Author: Urvang (urvang@google.com)
  13
  14 #ifndef WEBP_WEBP_FORMAT_CONSTANTS_H_
  15 #define WEBP_WEBP_FORMAT_CONSTANTS_H_
  16
  17 // Create fourcc of the chunk from the chunk tag characters.
  18 #define MKFOURCC(a, b, c, d) ((uint32_t)(a) | (b) << 8 | (c) << 16 | (d) << 24)
  19
  20 // VP8 related constants.
  21 #define VP8_SIGNATURE 0x9d012a              // Signature in VP8 data.
  22 #define VP8_MAX_PARTITION0_SIZE (1 << 19)   // max size of mode partition
  23 #define VP8_MAX_PARTITION_SIZE  (1 << 24)   // max size for token partition
  24 #define VP8_FRAME_HEADER_SIZE 10  // Size of the frame header within VP8 data.
  25
  26 // VP8L related constants.
  27 #define VP8L_SIGNATURE_SIZE          1      // VP8L signature size.
  28 #define VP8L_MAGIC_BYTE              0x2f   // VP8L signature byte.
  29 #define VP8L_IMAGE_SIZE_BITS         14     // Number of bits used to store
  30                                             // width and height.
  31 #define VP8L_VERSION_BITS            3      // 3 bits reserved for version.
  32 #define VP8L_VERSION                 0      // version 0
  33 #define VP8L_FRAME_HEADER_SIZE       5      // Size of the VP8L frame header.
  34
  35 #define MAX_PALETTE_SIZE             256
  36 #define MAX_CACHE_BITS               11
  37 #define HUFFMAN_CODES_PER_META_CODE  5
  38 #define ARGB_BLACK                   0xff000000
  39
  40 #define DEFAULT_CODE_LENGTH          8
  41 #define MAX_ALLOWED_CODE_LENGTH      15
  42
  43 #define NUM_LITERAL_CODES            256
  44 #define NUM_LENGTH_CODES             24
  45 #define NUM_DISTANCE_CODES           40
  46 #define CODE_LENGTH_CODES            19
  47
  48 #define MIN_HUFFMAN_BITS             2  // min number of Huffman bits
  49 #define MAX_HUFFMAN_BITS             9  // max number of Huffman bits
  50
  51 #define TRANSFORM_PRESENT            1  // The bit to be written when next data
  52                                         // to be read is a transform.
  53 #define NUM_TRANSFORMS               4  // Maximum number of allowed transform
  54                                         // in a bitstream.
  55 typedef enum {
  56   PREDICTOR_TRANSFORM      = 0,
  57   CROSS_COLOR_TRANSFORM    = 1,
  58   SUBTRACT_GREEN           = 2,
  59   COLOR_INDEXING_TRANSFORM = 3
  60 } VP8LImageTransformType;
  61
  62 // Alpha related constants.
  63 #define ALPHA_HEADER_LEN            1
  64 #define ALPHA_NO_COMPRESSION        0
  65 #define ALPHA_LOSSLESS_COMPRESSION  1
  66 #define ALPHA_PREPROCESSED_LEVELS   1
  67
  68 // Mux related constants.
  69 #define TAG_SIZE           4     // Size of a chunk tag (e.g. "VP8L").
  70 #define CHUNK_SIZE_BYTES   4     // Size needed to store chunk's size.
  71 #define CHUNK_HEADER_SIZE  8     // Size of a chunk header.
  72 #define RIFF_HEADER_SIZE   12    // Size of the RIFF header ("RIFFnnnnWEBP").
  73 #define ANMF_CHUNK_SIZE    16    // Size of an ANMF chunk.
  74 #define ANIM_CHUNK_SIZE    6     // Size of an ANIM chunk.
  75 #define FRGM_CHUNK_SIZE    6     // Size of a FRGM chunk.
  76 #define VP8X_CHUNK_SIZE    10    // Size of a VP8X chunk.
  77
  78 #define MAX_CANVAS_SIZE     (1 << 24)     // 24-bit max for VP8X width/height.
  79 #define MAX_IMAGE_AREA      (1ULL << 32)  // 32-bit max for width x height.
  80 #define MAX_LOOP_COUNT      (1 << 16)     // maximum value for loop-count
  81 #define MAX_DURATION        (1 << 24)     // maximum duration
  82 #define MAX_POSITION_OFFSET (1 << 24)     // maximum frame/fragment x/y offset
  83
  84 // Maximum chunk payload is such that adding the header and padding won't
  85 // overflow a uint32_t.
  86 #define MAX_CHUNK_PAYLOAD (~0U - CHUNK_HEADER_SIZE - 1)
  87
  88 #endif  /* WEBP_WEBP_FORMAT_CONSTANTS_H_ */