From 9880ec62822d86d97491bac181329907f625b52f Mon Sep 17 00:00:00 2001 From: David Rosca Date: Tue, 2 May 2023 13:14:18 +0200 Subject: [PATCH] libobs: Add AV1 parsing functions 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. --- libobs/CMakeLists.txt | 2 + libobs/cmake/legacy.cmake | 2 + libobs/obs-av1.c | 123 ++++++++++++++++++++++++++++++++++++++ libobs/obs-av1.h | 35 +++++++++++ 4 files changed, 162 insertions(+) create mode 100644 libobs/obs-av1.c create mode 100644 libobs/obs-av1.h diff --git a/libobs/CMakeLists.txt b/libobs/CMakeLists.txt index 46112abe71f9d..36a75713c001f 100644 --- a/libobs/CMakeLists.txt +++ b/libobs/CMakeLists.txt @@ -33,6 +33,8 @@ target_sources( obs-audio-controls.c obs-audio-controls.h obs-audio.c + obs-av1.c + obs-av1.h obs-avc.c obs-avc.h obs-data.c diff --git a/libobs/cmake/legacy.cmake b/libobs/cmake/legacy.cmake index 5f13c4c0f04ab..dd77cdfb94229 100644 --- a/libobs/cmake/legacy.cmake +++ b/libobs/cmake/legacy.cmake @@ -32,6 +32,8 @@ target_sources( obs-audio.c obs-audio-controls.c obs-audio-controls.h + obs-av1.c + obs-av1.h obs-avc.c obs-avc.h obs-data.c diff --git a/libobs/obs-av1.c b/libobs/obs-av1.c new file mode 100644 index 0000000000000..a015130537cf2 --- /dev/null +++ b/libobs/obs-av1.c @@ -0,0 +1,123 @@ +// SPDX-FileCopyrightText: 2023 David Rosca +// +// SPDX-License-Identifier: GPL-2.0-or-later + +#include "obs-av1.h" + +#include "obs.h" + +static inline uint64_t leb128(const uint8_t *buf, size_t size, size_t *len) +{ + uint64_t value = 0; + uint8_t leb128_byte; + + *len = 0; + + for (int i = 0; i < 8; i++) { + if (size-- < 1) + break; + (*len)++; + leb128_byte = buf[i]; + value |= (leb128_byte & 0x7f) << (i * 7); + if (!(leb128_byte & 0x80)) + break; + } + + return value; +} + +static inline unsigned int get_bits(uint8_t val, unsigned int n, + unsigned int count) +{ + return (val >> (8 - n - count)) & ((1 << (count - 1)) * 2 - 1); +} + +static void parse_obu_header(const uint8_t *buf, size_t size, size_t *obu_start, + size_t *obu_size, int *obu_type) +{ + int extension_flag, has_size_field; + size_t size_len = 0; + + *obu_start = 0; + *obu_size = 0; + *obu_type = 0; + + if (size < 1) + return; + + *obu_type = get_bits(*buf, 1, 4); + extension_flag = get_bits(*buf, 5, 1); + has_size_field = get_bits(*buf, 6, 1); + + if (extension_flag) + (*obu_start)++; + + (*obu_start)++; + + if (has_size_field) + *obu_size = (size_t)leb128(buf + *obu_start, size - *obu_start, + &size_len); + else + *obu_size = size - 1; + + *obu_start += size_len; +} + +bool obs_av1_keyframe(const uint8_t *data, size_t size) +{ + const uint8_t *start = data, *end = data + size; + + while (start < end) { + size_t obu_start, obu_size; + int obu_type; + parse_obu_header(start, end - start, &obu_start, &obu_size, + &obu_type); + + if (obu_size) { + if (obu_type == OBS_OBU_FRAME || + obu_type == OBS_OBU_FRAME_HEADER) { + uint8_t val = *(start + obu_start); + if (!get_bits(val, 0, 1)) // show_existing_frame + return get_bits(val, 1, 2) == + 0; // frame_type + return false; + } + } + + start += obu_start + obu_size; + } + + return false; +} + +void obs_extract_av1_headers(const uint8_t *packet, size_t size, + uint8_t **new_packet_data, size_t *new_packet_size, + uint8_t **header_data, size_t *header_size) +{ + DARRAY(uint8_t) new_packet; + DARRAY(uint8_t) header; + const uint8_t *start = packet, *end = packet + size; + + da_init(new_packet); + da_init(header); + + while (start < end) { + size_t obu_start, obu_size; + int obu_type; + parse_obu_header(start, end - start, &obu_start, &obu_size, + &obu_type); + + if (obu_type == OBS_OBU_METADATA || + obu_type == OBS_OBU_SEQUENCE_HEADER) { + da_push_back_array(header, start, obu_start + obu_size); + } + da_push_back_array(new_packet, start, obu_start + obu_size); + + start += obu_start + obu_size; + } + + *new_packet_data = new_packet.array; + *new_packet_size = new_packet.num; + *header_data = header.array; + *header_size = header.num; +} diff --git a/libobs/obs-av1.h b/libobs/obs-av1.h new file mode 100644 index 0000000000000..031299da0a415 --- /dev/null +++ b/libobs/obs-av1.h @@ -0,0 +1,35 @@ +// SPDX-FileCopyrightText: 2023 David Rosca +// +// SPDX-License-Identifier: GPL-2.0-or-later + +#pragma once + +#include "util/c99defs.h" + +#ifdef __cplusplus +extern "C" { +#endif + +enum { + OBS_OBU_SEQUENCE_HEADER = 1, + OBS_OBU_TEMPORAL_DELIMITER = 2, + OBS_OBU_FRAME_HEADER = 3, + OBS_OBU_TILE_GROUP = 4, + OBS_OBU_METADATA = 5, + OBS_OBU_FRAME = 6, + OBS_OBU_REDUNDANT_FRAME_HEADER = 7, + OBS_OBU_TILE_LIST = 8, + OBS_OBU_PADDING = 15, +}; + +/* Helpers for parsing AV1 OB units. */ + +EXPORT bool obs_av1_keyframe(const uint8_t *data, size_t size); +EXPORT void obs_extract_av1_headers(const uint8_t *packet, size_t size, + uint8_t **new_packet_data, + size_t *new_packet_size, + uint8_t **header_data, size_t *header_size); + +#ifdef __cplusplus +} +#endif