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127 lines
3.5 KiB
C
127 lines
3.5 KiB
C
/*
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* AV1 common parsing code
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef AVCODEC_AV1_PARSE_H
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#define AVCODEC_AV1_PARSE_H
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#include <stdint.h>
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#include "avcodec.h"
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#include "get_bits.h"
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typedef struct AV1OBU {
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/** Size of payload */
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int size;
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const uint8_t *data;
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/** Size of entire OBU, including header */
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int raw_size;
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const uint8_t *raw_data;
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/** GetBitContext initialized to the start of the payload */
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GetBitContext gb;
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int type;
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int temporal_id;
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int spatial_id;
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} AV1OBU;
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/** An input packet split into OBUs */
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typedef struct AV1Packet {
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AV1OBU *obus;
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int nb_obus;
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int obus_allocated;
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} AV1Packet;
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/**
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* Extract an OBU from a raw bitstream.
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*
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* @note This function does not copy or store any bistream data. All
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* the pointers in the AV1OBU structure will be valid as long
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* as the input buffer also is.
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*/
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int ff_av1_extract_obu(AV1OBU *obu, const uint8_t *buf, int length,
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void *logctx);
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/**
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* Split an input packet into OBUs.
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*
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* @note This function does not copy or store any bistream data. All
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* the pointers in the AV1Packet structure will be valid as
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* long as the input buffer also is.
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*/
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int ff_av1_packet_split(AV1Packet *pkt, const uint8_t *buf, int length,
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void *logctx);
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/**
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* Free all the allocated memory in the packet.
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*/
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void ff_av1_packet_uninit(AV1Packet *pkt);
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static inline int64_t leb128(GetBitContext *gb) {
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int64_t ret = 0;
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int i;
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for (i = 0; i < 8; i++) {
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int byte = get_bits(gb, 8);
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ret |= (int64_t)(byte & 0x7f) << (i * 7);
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if (!(byte & 0x80))
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break;
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}
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return ret;
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}
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static inline int parse_obu_header(const uint8_t *buf, int buf_size,
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int64_t *obu_size, int *start_pos, int *type,
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int *temporal_id, int *spatial_id)
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{
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GetBitContext gb;
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int ret, extension_flag, has_size_flag;
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ret = init_get_bits8(&gb, buf, FFMIN(buf_size, 2 + 8)); // OBU header fields + max leb128 length
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if (ret < 0)
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return ret;
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if (get_bits1(&gb) != 0) // obu_forbidden_bit
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return AVERROR_INVALIDDATA;
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*type = get_bits(&gb, 4);
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extension_flag = get_bits1(&gb);
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has_size_flag = get_bits1(&gb);
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skip_bits1(&gb); // obu_reserved_1bit
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if (extension_flag) {
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*temporal_id = get_bits(&gb, 3);
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*spatial_id = get_bits(&gb, 2);
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skip_bits(&gb, 3); // extension_header_reserved_3bits
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} else {
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*temporal_id = *spatial_id = 0;
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}
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*obu_size = has_size_flag ? leb128(&gb)
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: buf_size - 1 - extension_flag;
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*start_pos = get_bits_count(&gb) / 8;
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return 0;
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}
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#endif /* AVCODEC_AV1_PARSE_H */
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