79 lines
2.6 KiB
C++
79 lines
2.6 KiB
C++
// Copyright 2019 Citra Emulator Project
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// Licensed under GPLv2 or any later version
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// Refer to the license.txt file included.
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#include <array>
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#include "adts.h"
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#include "common/bit_field.h"
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namespace AudioCore {
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constexpr std::array<u32, 16> freq_table = {96000, 88200, 64000, 48000, 44100, 32000, 24000, 22050,
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16000, 12000, 11025, 8000, 7350, 0, 0, 0};
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constexpr std::array<u8, 8> channel_table = {0, 1, 2, 3, 4, 5, 6, 8};
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struct ADTSHeader {
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union {
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std::array<u8, 7> raw{};
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BitFieldBE<52, 12, u64> sync_word;
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BitFieldBE<51, 1, u64> mpeg2;
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BitFieldBE<49, 2, u64> layer;
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BitFieldBE<48, 1, u64> protection_absent;
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BitFieldBE<46, 2, u64> profile;
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BitFieldBE<42, 4, u64> samplerate_idx;
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BitFieldBE<41, 1, u64> private_bit;
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BitFieldBE<38, 3, u64> channel_idx;
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BitFieldBE<37, 1, u64> originality;
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BitFieldBE<36, 1, u64> home;
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BitFieldBE<35, 1, u64> copyright_id;
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BitFieldBE<34, 1, u64> copyright_id_start;
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BitFieldBE<21, 13, u64> frame_length;
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BitFieldBE<10, 11, u64> buffer_fullness;
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BitFieldBE<8, 2, u64> frame_count;
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};
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};
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ADTSData ParseADTS(const u8* buffer) {
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ADTSHeader header;
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memcpy(header.raw.data(), buffer, sizeof(header.raw));
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// sync word 0xfff
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if (header.sync_word != 0xfff) {
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return {};
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}
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ADTSData out{};
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// bit 16 = no CRC
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out.header_length = header.protection_absent ? 7 : 9;
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out.mpeg2 = static_cast<bool>(header.mpeg2);
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// bit 17 to 18
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out.profile = static_cast<u8>(header.profile) + 1;
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// bit 19 to 22
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out.samplerate_idx = static_cast<u8>(header.samplerate_idx);
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out.samplerate = header.samplerate_idx > 15 ? 0 : freq_table[header.samplerate_idx];
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// bit 24 to 26
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out.channel_idx = static_cast<u8>(header.channel_idx);
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out.channels = (header.channel_idx > 7) ? 0 : channel_table[header.channel_idx];
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// bit 55 to 56
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out.framecount = static_cast<u8>(header.frame_count + 1);
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// bit 31 to 43
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out.length = static_cast<u32>(header.frame_length);
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return out;
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}
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// last two bytes of MF AAC decoder user data
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// Audio object type (5 bits)
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// Sample rate profile (4 bits)
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// Channel configuration profile (4 bits)
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// Frame length flag (1 bit)
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// Depends on core coder (1 bit)
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// Extension flag (1 bit)
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u16 MFGetAACTag(const ADTSData& input) {
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u16 tag = 0;
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tag |= input.profile << 11;
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tag |= input.samplerate_idx << 7;
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tag |= input.channel_idx << 3;
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return tag;
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}
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} // namespace AudioCore
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