diff options
Diffstat (limited to 'media/libaom/src/av1/common/obu_util.c')
| -rw-r--r-- | media/libaom/src/av1/common/obu_util.c | 147 |
1 files changed, 147 insertions, 0 deletions
diff --git a/media/libaom/src/av1/common/obu_util.c b/media/libaom/src/av1/common/obu_util.c new file mode 100644 index 000000000..823b700b1 --- /dev/null +++ b/media/libaom/src/av1/common/obu_util.c @@ -0,0 +1,147 @@ +/* + * 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; +} |