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/*
* Copyright (c) 2018, Alliance for Open Media. All rights reserved
*
* This source code is subject to the terms of the BSD 2 Clause License and
* the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
* was not distributed with this source code in the LICENSE file, you can
* obtain it at www.aomedia.org/license/software. If the Alliance for Open
* Media Patent License 1.0 was not distributed with this source code in the
* PATENTS file, you can obtain it at www.aomedia.org/license/patent.
*/
#include "av1/common/obu_util.h"
#include "aom_dsp/bitreader_buffer.h"
// Returns 1 when OBU type is valid, and 0 otherwise.
static int valid_obu_type(int obu_type) {
int valid_type = 0;
switch (obu_type) {
case OBU_SEQUENCE_HEADER:
case OBU_TEMPORAL_DELIMITER:
case OBU_FRAME_HEADER:
case OBU_TILE_GROUP:
case OBU_METADATA:
case OBU_FRAME:
case OBU_REDUNDANT_FRAME_HEADER:
case OBU_TILE_LIST:
case OBU_PADDING: valid_type = 1; break;
default: break;
}
return valid_type;
}
static aom_codec_err_t read_obu_size(const uint8_t *data,
size_t bytes_available,
size_t *const obu_size,
size_t *const length_field_size) {
uint64_t u_obu_size = 0;
if (aom_uleb_decode(data, bytes_available, &u_obu_size, length_field_size) !=
0) {
return AOM_CODEC_CORRUPT_FRAME;
}
if (u_obu_size > UINT32_MAX) return AOM_CODEC_CORRUPT_FRAME;
*obu_size = (size_t)u_obu_size;
return AOM_CODEC_OK;
}
// Parses OBU header and stores values in 'header'.
static aom_codec_err_t read_obu_header(struct aom_read_bit_buffer *rb,
int is_annexb, ObuHeader *header) {
if (!rb || !header) return AOM_CODEC_INVALID_PARAM;
const ptrdiff_t bit_buffer_byte_length = rb->bit_buffer_end - rb->bit_buffer;
if (bit_buffer_byte_length < 1) return AOM_CODEC_CORRUPT_FRAME;
header->size = 1;
if (aom_rb_read_bit(rb) != 0) {
// Forbidden bit. Must not be set.
return AOM_CODEC_CORRUPT_FRAME;
}
header->type = (OBU_TYPE)aom_rb_read_literal(rb, 4);
if (!valid_obu_type(header->type)) return AOM_CODEC_CORRUPT_FRAME;
header->has_extension = aom_rb_read_bit(rb);
header->has_size_field = aom_rb_read_bit(rb);
if (!header->has_size_field && !is_annexb) {
// section 5 obu streams must have obu_size field set.
return AOM_CODEC_UNSUP_BITSTREAM;
}
if (aom_rb_read_bit(rb) != 0) {
// obu_reserved_1bit must be set to 0.
return AOM_CODEC_CORRUPT_FRAME;
}
if (header->has_extension) {
if (bit_buffer_byte_length == 1) return AOM_CODEC_CORRUPT_FRAME;
header->size += 1;
header->temporal_layer_id = aom_rb_read_literal(rb, 3);
header->spatial_layer_id = aom_rb_read_literal(rb, 2);
if (aom_rb_read_literal(rb, 3) != 0) {
// extension_header_reserved_3bits must be set to 0.
return AOM_CODEC_CORRUPT_FRAME;
}
}
return AOM_CODEC_OK;
}
aom_codec_err_t aom_read_obu_header(uint8_t *buffer, size_t buffer_length,
size_t *consumed, ObuHeader *header,
int is_annexb) {
if (buffer_length < 1 || !consumed || !header) return AOM_CODEC_INVALID_PARAM;
// TODO(tomfinegan): Set the error handler here and throughout this file, and
// confirm parsing work done via aom_read_bit_buffer is successful.
struct aom_read_bit_buffer rb = { buffer, buffer + buffer_length, 0, NULL,
NULL };
aom_codec_err_t parse_result = read_obu_header(&rb, is_annexb, header);
if (parse_result == AOM_CODEC_OK) *consumed = header->size;
return parse_result;
}
aom_codec_err_t 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) {
size_t length_field_size = 0, obu_size = 0;
aom_codec_err_t status;
if (is_annexb) {
// Size field comes before the OBU header, and includes the OBU header
status =
read_obu_size(data, bytes_available, &obu_size, &length_field_size);
if (status != AOM_CODEC_OK) return status;
}
struct aom_read_bit_buffer rb = { data + length_field_size,
data + bytes_available, 0, NULL, NULL };
status = read_obu_header(&rb, is_annexb, obu_header);
if (status != AOM_CODEC_OK) return status;
if (is_annexb) {
// Derive the payload size from the data we've already read
if (obu_size < obu_header->size) return AOM_CODEC_CORRUPT_FRAME;
*payload_size = obu_size - obu_header->size;
} else {
// Size field comes after the OBU header, and is just the payload size
status = read_obu_size(data + obu_header->size,
bytes_available - obu_header->size, payload_size,
&length_field_size);
if (status != AOM_CODEC_OK) return status;
}
*bytes_read = length_field_size + obu_header->size;
return AOM_CODEC_OK;
}
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