151 lines
3.9 KiB
C++
151 lines
3.9 KiB
C++
/*
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* Copyright 2003-2022 The Music Player Daemon Project
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* http://www.musicpd.org
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program 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
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#ifndef MPD_MUSIC_CHUNK_HXX
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#define MPD_MUSIC_CHUNK_HXX
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#include "MusicChunkPtr.hxx"
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#include "Chrono.hxx"
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#include "tag/ReplayGainInfo.hxx"
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#ifndef NDEBUG
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#include "pcm/AudioFormat.hxx"
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#endif
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#include <cstddef>
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#include <cstdint>
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#include <memory>
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#include <span>
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static constexpr size_t CHUNK_SIZE = 4096;
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struct AudioFormat;
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struct Tag;
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struct MusicChunk;
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/**
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* Meta information for #MusicChunk.
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*/
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struct MusicChunkInfo {
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/** the next chunk in a linked list */
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MusicChunkPtr next;
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/**
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* An optional chunk which should be mixed into this chunk.
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* This is used for cross-fading.
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*/
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MusicChunkPtr other;
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/**
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* An optional tag associated with this chunk (and the
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* following chunks); appears at song boundaries.
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*/
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std::unique_ptr<Tag> tag;
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/**
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* The current mix ratio for cross-fading: 1.0 means play 100%
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* of this chunk, 0.0 means play 100% of the "other" chunk.
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*/
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float mix_ratio;
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/** number of bytes stored in this chunk */
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uint16_t length = 0;
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/** current bit rate of the source file */
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uint16_t bit_rate;
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/** the time stamp within the song */
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SignedSongTime time;
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/**
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* Replay gain information associated with this chunk.
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* Only valid if the serial is not 0.
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*/
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ReplayGainInfo replay_gain_info;
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/**
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* A serial number for checking if replay gain info has
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* changed since the last chunk. The magic value 0 indicates
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* that there is no replay gain info available.
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*/
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unsigned replay_gain_serial;
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#ifndef NDEBUG
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AudioFormat audio_format;
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#endif
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MusicChunkInfo() noexcept;
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~MusicChunkInfo() noexcept;
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MusicChunkInfo(const MusicChunkInfo &) = delete;
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MusicChunkInfo &operator=(const MusicChunkInfo &) = delete;
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bool IsEmpty() const {
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return length == 0 && tag == nullptr;
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}
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#ifndef NDEBUG
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/**
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* Checks if the audio format if the chunk is equal to the
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* specified audio_format.
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*/
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[[gnu::pure]]
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bool CheckFormat(AudioFormat audio_format) const noexcept;
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#endif
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};
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/**
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* A chunk of music data. Its format is defined by the
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* MusicPipe::Push() caller.
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*/
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struct MusicChunk : MusicChunkInfo {
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/** the data (probably PCM) */
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std::byte data[CHUNK_SIZE - sizeof(MusicChunkInfo)];
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/**
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* Prepares appending to the music chunk. Returns a buffer
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* where you may write into. After you are finished, call
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* Expand().
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*
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* @param af the audio format for the appended data;
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* must stay the same for the life cycle of this chunk
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* @param data_time the time within the song
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* @param bit_rate the current bit rate of the source file
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* @return a writable buffer, or nullptr if the chunk is full
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*/
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std::span<std::byte> Write(AudioFormat af,
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SongTime data_time,
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uint16_t bit_rate) noexcept;
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/**
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* Increases the length of the chunk after the caller has written to
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* the buffer returned by Write().
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*
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* @param af the audio format for the appended data; must
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* stay the same for the life cycle of this chunk
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* @param length the number of bytes which were appended
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* @return true if the chunk is full
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*/
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bool Expand(AudioFormat af, size_t length) noexcept;
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};
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static_assert(sizeof(MusicChunk) == CHUNK_SIZE, "Wrong size");
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#endif
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