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722ca8447e
One notable difference from the AVC/HEVC code is that it also inserts the METADATA and SEQUENCE_HEADER OBUs into new_packet, otherwise the resulting video file wouldn't play.
124 lines
2.6 KiB
C
124 lines
2.6 KiB
C
// SPDX-FileCopyrightText: 2023 David Rosca <nowrep@gmail.com>
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//
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// SPDX-License-Identifier: GPL-2.0-or-later
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#include "obs-av1.h"
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#include "obs.h"
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static inline uint64_t leb128(const uint8_t *buf, size_t size, size_t *len)
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{
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uint64_t value = 0;
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uint8_t leb128_byte;
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*len = 0;
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for (int i = 0; i < 8; i++) {
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if (size-- < 1)
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break;
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(*len)++;
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leb128_byte = buf[i];
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value |= (leb128_byte & 0x7f) << (i * 7);
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if (!(leb128_byte & 0x80))
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break;
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}
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return value;
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}
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static inline unsigned int get_bits(uint8_t val, unsigned int n,
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unsigned int count)
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{
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return (val >> (8 - n - count)) & ((1 << (count - 1)) * 2 - 1);
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}
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static void parse_obu_header(const uint8_t *buf, size_t size, size_t *obu_start,
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size_t *obu_size, int *obu_type)
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{
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int extension_flag, has_size_field;
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size_t size_len = 0;
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*obu_start = 0;
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*obu_size = 0;
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*obu_type = 0;
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if (size < 1)
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return;
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*obu_type = get_bits(*buf, 1, 4);
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extension_flag = get_bits(*buf, 5, 1);
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has_size_field = get_bits(*buf, 6, 1);
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if (extension_flag)
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(*obu_start)++;
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(*obu_start)++;
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if (has_size_field)
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*obu_size = (size_t)leb128(buf + *obu_start, size - *obu_start,
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&size_len);
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else
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*obu_size = size - 1;
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*obu_start += size_len;
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}
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bool obs_av1_keyframe(const uint8_t *data, size_t size)
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{
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const uint8_t *start = data, *end = data + size;
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while (start < end) {
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size_t obu_start, obu_size;
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int obu_type;
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parse_obu_header(start, end - start, &obu_start, &obu_size,
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&obu_type);
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if (obu_size) {
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if (obu_type == OBS_OBU_FRAME ||
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obu_type == OBS_OBU_FRAME_HEADER) {
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uint8_t val = *(start + obu_start);
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if (!get_bits(val, 0, 1)) // show_existing_frame
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return get_bits(val, 1, 2) ==
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0; // frame_type
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return false;
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}
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}
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start += obu_start + obu_size;
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}
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return false;
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}
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void obs_extract_av1_headers(const uint8_t *packet, size_t size,
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uint8_t **new_packet_data, size_t *new_packet_size,
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uint8_t **header_data, size_t *header_size)
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{
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DARRAY(uint8_t) new_packet;
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DARRAY(uint8_t) header;
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const uint8_t *start = packet, *end = packet + size;
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da_init(new_packet);
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da_init(header);
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while (start < end) {
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size_t obu_start, obu_size;
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int obu_type;
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parse_obu_header(start, end - start, &obu_start, &obu_size,
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&obu_type);
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if (obu_type == OBS_OBU_METADATA ||
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obu_type == OBS_OBU_SEQUENCE_HEADER) {
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da_push_back_array(header, start, obu_start + obu_size);
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}
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da_push_back_array(new_packet, start, obu_start + obu_size);
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start += obu_start + obu_size;
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}
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*new_packet_data = new_packet.array;
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*new_packet_size = new_packet.num;
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*header_data = header.array;
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*header_size = header.num;
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}
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