330c8f8b93
Add RTP packetizer and depacketizer according to (most) of the official AV1 RTP specification. This enables streaming via RTSP between ffmpeg and ffmpeg and has also been tested to work with AV1 RTSP streams via GStreamer. It also adds the required SDP attributes for AV1. AV1 RTP encoding is marked as experimental due to draft specification status, debug amount reduced and other changes suggested by Tristan. Added optional code for searching the sequence header to determine the first packet for broken AV1 encoders / parsers. Stops depacketizing on corruption until next keyframe, no longer prematurely issues packet on decoding if temporal unit was not complete yet. Change-Id: I90f5c5b9d577908a0d713606706b5654fde5f910 Signed-off-by: Chris Hodges <chrishod@axis.com> Signed-off-by: Ronald S. Bultje <rsbultje@gmail.com>
128 lines
4.5 KiB
C
128 lines
4.5 KiB
C
/*
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* Shared definitions and helper functions for
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* AV1 (de)packetization.
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* Copyright (c) 2024 Axis Communications
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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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/**
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* @file
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* @brief shared defines and functions for AV1 RTP dec/enc
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* @author Chris Hodges <chris.hodges@axis.com>
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*/
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#ifndef AVFORMAT_RTP_AV1_H
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#define AVFORMAT_RTP_AV1_H
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// define a couple of flags and bit fields
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#define AV1B_OBU_FORBIDDEN 7
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#define AV1F_OBU_FORBIDDEN (1u << AV1B_OBU_FORBIDDEN)
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#define AV1S_OBU_TYPE 3
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#define AV1M_OBU_TYPE 15
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#define AV1B_OBU_EXTENSION_FLAG 2
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#define AV1F_OBU_EXTENSION_FLAG (1u << AV1B_OBU_EXTENSION_FLAG)
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#define AV1B_OBU_HAS_SIZE_FIELD 1
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#define AV1F_OBU_HAS_SIZE_FIELD (1u << AV1B_OBU_HAS_SIZE_FIELD)
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#define AV1B_OBU_RESERVED_1BIT 0
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#define AV1F_OBU_RESERVED_1BIT (1u << AV1B_OBU_RESERVED_1BIT)
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#define AV1B_AGGR_HDR_FRAG_CONT 7
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#define AV1F_AGGR_HDR_FRAG_CONT (1u << AV1B_AGGR_HDR_FRAG_CONT)
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#define AV1B_AGGR_HDR_LAST_FRAG 6
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#define AV1F_AGGR_HDR_LAST_FRAG (1u << AV1B_AGGR_HDR_LAST_FRAG)
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#define AV1S_AGGR_HDR_NUM_OBUS 4
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#define AV1M_AGGR_HDR_NUM_OBUS 3
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#define AV1B_AGGR_HDR_FIRST_PKT 3
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#define AV1F_AGGR_HDR_FIRST_PKT (1u << AV1B_AGGR_HDR_FIRST_PKT)
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/// calculate number of required LEB bytes for the given length
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static inline unsigned int calc_leb_size(uint32_t length) {
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unsigned int num_lebs = 0;
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do {
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num_lebs++;
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length >>= 7;
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} while (length);
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return num_lebs;
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}
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/// write out variable number of LEB bytes for the given length
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static inline unsigned int write_leb(uint8_t *lebptr, uint32_t length) {
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unsigned int num_lebs = 0;
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do {
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num_lebs++;
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if (length < 0x80) {
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*lebptr = length;
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break;
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}
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*lebptr++ = length | 0x80; // no need to mask out
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length >>= 7;
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} while (1);
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return num_lebs;
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}
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/// write out fixed number of LEB bytes (may have "unused" bytes)
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static inline void write_leb_n(uint8_t *lebptr, uint32_t length, unsigned int num_lebs) {
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for (int i = 0; i < num_lebs; i++) {
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if (i == num_lebs - 1) {
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*lebptr = length & 0x7f;
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} else {
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*lebptr++ = length | 0x80; // no need to mask out
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}
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length >>= 7;
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}
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}
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/// securely parse LEB bytes and return the resulting encoded length
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static inline unsigned int parse_leb(AVFormatContext *ctx, const uint8_t *buf_ptr,
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uint32_t buffer_size, uint32_t *obu_size) {
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uint8_t leb128;
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unsigned int num_lebs = 0;
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*obu_size = 0;
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do {
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uint32_t leb7;
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if (!buffer_size) {
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av_log(ctx, AV_LOG_ERROR, "AV1: Out of data in OBU size field AV1 RTP packet\n");
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return 0;
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}
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leb128 = *buf_ptr++;
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leb7 = leb128 & 0x7f;
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buffer_size--;
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/* AV1 spec says that the maximum value returned from leb128 must fit in
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* 32 bits, so if the next byte will shift data out, we have some kind
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* of violation here. It is legal, though, to have the most significant
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* bytes with all zero bits (in the lower 7 bits). */
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if (((num_lebs == 4) && (leb7 >= 0x10)) || ((num_lebs > 4) && leb7)) {
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av_log(ctx, AV_LOG_ERROR, "AV1: OBU size field exceeds 32 bit in AV1 RTP packet\n");
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return 0;
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}
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if ((num_lebs == 7) && (leb128 >= 0x80)) {
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/* leb128 is defined to be up to 8 bytes (why???), 8th byte MUST NOT
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* indicate continuation */
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av_log(ctx, AV_LOG_ERROR, "AV1: OBU size field consists of too many bytes in AV1 RTP packet\n");
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return 0;
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}
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// shifts >= 32 are undefined in C!
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if (num_lebs <= 4) {
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*obu_size |= leb7 << (7 * num_lebs);
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}
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num_lebs++;
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} while (leb128 >= 0x80);
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return num_lebs;
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}
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#endif /* AVFORMAT_RTP_AV1_H */
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