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
read_obu_size(const uint8_t * data,size_t bytes_available,size_t * const obu_size,size_t * const length_field_size)17 static aom_codec_err_t read_obu_size(const uint8_t *data,
18 size_t bytes_available,
19 size_t *const obu_size,
20 size_t *const length_field_size) {
21 uint64_t u_obu_size = 0;
22 if (aom_uleb_decode(data, bytes_available, &u_obu_size, length_field_size) !=
23 0) {
24 return AOM_CODEC_CORRUPT_FRAME;
25 }
26
27 if (u_obu_size > UINT32_MAX) return AOM_CODEC_CORRUPT_FRAME;
28 *obu_size = (size_t)u_obu_size;
29 return AOM_CODEC_OK;
30 }
31
32 // Parses OBU header and stores values in 'header'.
read_obu_header(struct aom_read_bit_buffer * rb,int is_annexb,ObuHeader * header)33 static aom_codec_err_t read_obu_header(struct aom_read_bit_buffer *rb,
34 int is_annexb, ObuHeader *header) {
35 if (!rb || !header) return AOM_CODEC_INVALID_PARAM;
36
37 const ptrdiff_t bit_buffer_byte_length = rb->bit_buffer_end - rb->bit_buffer;
38 if (bit_buffer_byte_length < 1) return AOM_CODEC_CORRUPT_FRAME;
39
40 header->size = 1;
41
42 if (aom_rb_read_bit(rb) != 0) {
43 // Forbidden bit. Must not be set.
44 return AOM_CODEC_CORRUPT_FRAME;
45 }
46
47 header->type = (OBU_TYPE)aom_rb_read_literal(rb, 4);
48 header->has_extension = aom_rb_read_bit(rb);
49 header->has_size_field = aom_rb_read_bit(rb);
50
51 if (!header->has_size_field && !is_annexb) {
52 // section 5 obu streams must have obu_size field set.
53 return AOM_CODEC_UNSUP_BITSTREAM;
54 }
55
56 // obu_reserved_1bit must be set to 0. The value is ignored by a decoder.
57 aom_rb_read_bit(rb);
58
59 if (header->has_extension) {
60 if (bit_buffer_byte_length == 1) return AOM_CODEC_CORRUPT_FRAME;
61
62 header->size += 1;
63 header->temporal_layer_id = aom_rb_read_literal(rb, 3);
64 header->spatial_layer_id = aom_rb_read_literal(rb, 2);
65 // extension_header_reserved_3bits must be set to 0. The value is ignored by
66 // a decoder.
67 aom_rb_read_literal(rb, 3);
68 } else {
69 header->temporal_layer_id = 0;
70 header->spatial_layer_id = 0;
71 }
72
73 return AOM_CODEC_OK;
74 }
75
aom_read_obu_header(uint8_t * buffer,size_t buffer_length,size_t * consumed,ObuHeader * header,int is_annexb)76 aom_codec_err_t aom_read_obu_header(uint8_t *buffer, size_t buffer_length,
77 size_t *consumed, ObuHeader *header,
78 int is_annexb) {
79 if (buffer_length < 1 || !consumed || !header) return AOM_CODEC_INVALID_PARAM;
80
81 // TODO(tomfinegan): Set the error handler here and throughout this file, and
82 // confirm parsing work done via aom_read_bit_buffer is successful.
83 struct aom_read_bit_buffer rb = { buffer, buffer + buffer_length, 0, NULL,
84 NULL };
85 aom_codec_err_t parse_result = read_obu_header(&rb, is_annexb, header);
86 if (parse_result == AOM_CODEC_OK) *consumed = header->size;
87 return parse_result;
88 }
89
aom_read_obu_header_and_size(const uint8_t * data,size_t bytes_available,int is_annexb,ObuHeader * obu_header,size_t * const payload_size,size_t * const bytes_read)90 aom_codec_err_t aom_read_obu_header_and_size(const uint8_t *data,
91 size_t bytes_available,
92 int is_annexb,
93 ObuHeader *obu_header,
94 size_t *const payload_size,
95 size_t *const bytes_read) {
96 size_t length_field_size_obu = 0;
97 size_t length_field_size_payload = 0;
98 size_t obu_size = 0;
99 aom_codec_err_t status;
100
101 if (is_annexb) {
102 // Size field comes before the OBU header, and includes the OBU header
103 status =
104 read_obu_size(data, bytes_available, &obu_size, &length_field_size_obu);
105
106 if (status != AOM_CODEC_OK) return status;
107 }
108
109 struct aom_read_bit_buffer rb = { data + length_field_size_obu,
110 data + bytes_available, 0, NULL, NULL };
111
112 status = read_obu_header(&rb, is_annexb, obu_header);
113 if (status != AOM_CODEC_OK) return status;
114
115 if (!obu_header->has_size_field) {
116 assert(is_annexb);
117 // Derive the payload size from the data we've already read
118 if (obu_size < obu_header->size) return AOM_CODEC_CORRUPT_FRAME;
119
120 *payload_size = obu_size - obu_header->size;
121 } else {
122 // Size field comes after the OBU header, and is just the payload size
123 status = read_obu_size(
124 data + length_field_size_obu + obu_header->size,
125 bytes_available - length_field_size_obu - obu_header->size,
126 payload_size, &length_field_size_payload);
127 if (status != AOM_CODEC_OK) return status;
128 }
129
130 *bytes_read =
131 length_field_size_obu + obu_header->size + length_field_size_payload;
132 return AOM_CODEC_OK;
133 }
134