1 /* 2 * Copyright (c) 2018, Alliance for Open Media. All rights reserved 3 * 4 * This source code is subject to the terms of the BSD 2 Clause License and 5 * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License 6 * was not distributed with this source code in the LICENSE file, you can 7 * obtain it at www.aomedia.org/license/software. If the Alliance for Open 8 * Media Patent License 1.0 was not distributed with this source code in the 9 * PATENTS file, you can obtain it at www.aomedia.org/license/patent. 10 */ 11 #include <assert.h> 12 13 #include "av1/common/obu_util.h" 14 15 #include "aom_dsp/bitreader_buffer.h" 16 17 // Returns 1 when OBU type is valid, and 0 otherwise. 18 static int valid_obu_type(int obu_type) { 19 int valid_type = 0; 20 switch (obu_type) { 21 case OBU_SEQUENCE_HEADER: 22 case OBU_TEMPORAL_DELIMITER: 23 case OBU_FRAME_HEADER: 24 case OBU_TILE_GROUP: 25 case OBU_METADATA: 26 case OBU_FRAME: 27 case OBU_REDUNDANT_FRAME_HEADER: 28 case OBU_TILE_LIST: 29 case OBU_PADDING: valid_type = 1; break; 30 default: break; 31 } 32 return valid_type; 33 } 34 35 static aom_codec_err_t read_obu_size(const uint8_t *data, 36 size_t bytes_available, 37 size_t *const obu_size, 38 size_t *const length_field_size) { 39 uint64_t u_obu_size = 0; 40 if (aom_uleb_decode(data, bytes_available, &u_obu_size, length_field_size) != 41 0) { 42 return AOM_CODEC_CORRUPT_FRAME; 43 } 44 45 if (u_obu_size > UINT32_MAX) return AOM_CODEC_CORRUPT_FRAME; 46 *obu_size = (size_t)u_obu_size; 47 return AOM_CODEC_OK; 48 } 49 50 // Parses OBU header and stores values in 'header'. 51 static aom_codec_err_t read_obu_header(struct aom_read_bit_buffer *rb, 52 int is_annexb, ObuHeader *header) { 53 if (!rb || !header) return AOM_CODEC_INVALID_PARAM; 54 55 const ptrdiff_t bit_buffer_byte_length = rb->bit_buffer_end - rb->bit_buffer; 56 if (bit_buffer_byte_length < 1) return AOM_CODEC_CORRUPT_FRAME; 57 58 header->size = 1; 59 60 if (aom_rb_read_bit(rb) != 0) { 61 // Forbidden bit. Must not be set. 62 return AOM_CODEC_CORRUPT_FRAME; 63 } 64 65 header->type = (OBU_TYPE)aom_rb_read_literal(rb, 4); 66 67 if (!valid_obu_type(header->type)) return AOM_CODEC_CORRUPT_FRAME; 68 69 header->has_extension = aom_rb_read_bit(rb); 70 header->has_size_field = aom_rb_read_bit(rb); 71 72 if (!header->has_size_field && !is_annexb) { 73 // section 5 obu streams must have obu_size field set. 74 return AOM_CODEC_UNSUP_BITSTREAM; 75 } 76 77 if (aom_rb_read_bit(rb) != 0) { 78 // obu_reserved_1bit must be set to 0. 79 return AOM_CODEC_CORRUPT_FRAME; 80 } 81 82 if (header->has_extension) { 83 if (bit_buffer_byte_length == 1) return AOM_CODEC_CORRUPT_FRAME; 84 85 header->size += 1; 86 header->temporal_layer_id = aom_rb_read_literal(rb, 3); 87 header->spatial_layer_id = aom_rb_read_literal(rb, 2); 88 if (aom_rb_read_literal(rb, 3) != 0) { 89 // extension_header_reserved_3bits must be set to 0. 90 return AOM_CODEC_CORRUPT_FRAME; 91 } 92 } 93 94 return AOM_CODEC_OK; 95 } 96 97 aom_codec_err_t aom_read_obu_header(uint8_t *buffer, size_t buffer_length, 98 size_t *consumed, ObuHeader *header, 99 int is_annexb) { 100 if (buffer_length < 1 || !consumed || !header) return AOM_CODEC_INVALID_PARAM; 101 102 // TODO(tomfinegan): Set the error handler here and throughout this file, and 103 // confirm parsing work done via aom_read_bit_buffer is successful. 104 struct aom_read_bit_buffer rb = { buffer, buffer + buffer_length, 0, NULL, 105 NULL }; 106 aom_codec_err_t parse_result = read_obu_header(&rb, is_annexb, header); 107 if (parse_result == AOM_CODEC_OK) *consumed = header->size; 108 return parse_result; 109 } 110 111 aom_codec_err_t aom_read_obu_header_and_size(const uint8_t *data, 112 size_t bytes_available, 113 int is_annexb, 114 ObuHeader *obu_header, 115 size_t *const payload_size, 116 size_t *const bytes_read) { 117 size_t length_field_size_obu = 0; 118 size_t length_field_size_payload = 0; 119 size_t obu_size = 0; 120 aom_codec_err_t status; 121 122 if (is_annexb) { 123 // Size field comes before the OBU header, and includes the OBU header 124 status = 125 read_obu_size(data, bytes_available, &obu_size, &length_field_size_obu); 126 127 if (status != AOM_CODEC_OK) return status; 128 } 129 130 struct aom_read_bit_buffer rb = { data + length_field_size_obu, 131 data + bytes_available, 0, NULL, NULL }; 132 133 status = read_obu_header(&rb, is_annexb, obu_header); 134 if (status != AOM_CODEC_OK) return status; 135 136 if (!obu_header->has_size_field) { 137 assert(is_annexb); 138 // Derive the payload size from the data we've already read 139 if (obu_size < obu_header->size) return AOM_CODEC_CORRUPT_FRAME; 140 141 *payload_size = obu_size - obu_header->size; 142 } else { 143 // Size field comes after the OBU header, and is just the payload size 144 status = read_obu_size( 145 data + length_field_size_obu + obu_header->size, 146 bytes_available - length_field_size_obu - obu_header->size, 147 payload_size, &length_field_size_payload); 148 if (status != AOM_CODEC_OK) return status; 149 } 150 151 *bytes_read = 152 length_field_size_obu + obu_header->size + length_field_size_payload; 153 return AOM_CODEC_OK; 154 } 155
