obs-StreamFX/source/encoders/codecs/h264.cpp

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// AUTOGENERATED COPYRIGHT HEADER START
// Copyright (C) 2020-2023 Michael Fabian 'Xaymar' Dirks <info@xaymar.com>
// AUTOGENERATED COPYRIGHT HEADER END
2020-01-13 00:52:30 +00:00
#include "h264.hpp"
uint8_t* is_nal_start(uint8_t* ptr, uint8_t* end_ptr, size_t& size)
{
// Ensure that the remaining space actually can contain a prefix and NAL header.
if ((ptr + (3 + 1)) >= end_ptr)
return nullptr;
if (*ptr != 0x0)
return nullptr;
if (*(ptr + 1) != 0x0)
return nullptr;
// 3-Byte NAL prefix.
if (*(ptr + 2) == 0x1) {
size = 3;
return ptr + 3;
}
// 4-Byte NAL Prefix
if ((ptr + (4 + 1)) >= end_ptr)
return nullptr;
if (*(ptr + 2) != 0x0)
return nullptr;
if (*(ptr + 3) != 0x01)
return nullptr;
size = 4;
return ptr + 4;
}
uint8_t* streamfx::encoder::codec::h264::find_closest_nal(uint8_t* ptr, uint8_t* end_ptr, size_t& size)
{
for (uint8_t* seek_ptr = ptr; seek_ptr < end_ptr; seek_ptr++) {
if (auto nal_ptr = is_nal_start(seek_ptr, end_ptr, size); nal_ptr != nullptr)
return nal_ptr;
}
return nullptr;
}
uint32_t streamfx::encoder::codec::h264::get_packet_reference_count(uint8_t* ptr, uint8_t* end_ptr)
{
size_t nal_ptr_prefix = 0;
uint8_t* nal_ptr = find_closest_nal(ptr, end_ptr, nal_ptr_prefix);
while ((nal_ptr != nullptr) && (nal_ptr < end_ptr)) {
// Try and figure out the actual size of the NAL.
size_t nal_end_ptr_prefix = 0;
uint8_t* nal_end_ptr = find_closest_nal(nal_ptr, end_ptr, nal_end_ptr_prefix);
size_t nal_size = (nal_end_ptr ? nal_end_ptr : end_ptr) - nal_ptr - nal_end_ptr_prefix;
// Try and figure out the ideal priority.
switch (static_cast<nal_unit_type>((*nal_ptr) & 0x5)) {
case nal_unit_type::CODED_SLICE_NONIDR:
return static_cast<uint32_t>((*nal_ptr >> 5) & 0x2);
case nal_unit_type::CODED_SLICE_IDR:
return static_cast<uint32_t>((*nal_ptr >> 5) & 0x2);
default:
break;
}
// Update our NAL pointer.
nal_ptr = nal_end_ptr;
}
return std::numeric_limits<uint32_t>::max();
}