316 lines
6.8 KiB
C++
316 lines
6.8 KiB
C++
/*
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* Copyright (C) 2003-2015 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_AUDIO_FORMAT_HXX
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#define MPD_AUDIO_FORMAT_HXX
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#include "Compiler.h"
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#include <stdint.h>
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#include <assert.h>
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#if defined(WIN32) && GCC_CHECK_VERSION(4,6)
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/* on WIN32, "FLOAT" is already defined, and this triggers -Wshadow */
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#pragma GCC diagnostic push
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#pragma GCC diagnostic ignored "-Wshadow"
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#endif
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enum class SampleFormat : uint8_t {
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UNDEFINED = 0,
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S8,
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S16,
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/**
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* Signed 24 bit integer samples, packed in 32 bit integers
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* (the most significant byte is filled with the sign bit).
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*/
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S24_P32,
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S32,
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/**
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* 32 bit floating point samples in the host's format. The
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* range is -1.0f to +1.0f.
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*/
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FLOAT,
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/**
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* Direct Stream Digital. 1-bit samples; each frame has one
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* byte (8 samples) per channel.
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*/
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DSD,
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};
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#if defined(WIN32) && GCC_CHECK_VERSION(4,6)
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#pragma GCC diagnostic pop
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#endif
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static constexpr unsigned MAX_CHANNELS = 8;
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/**
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* This structure describes the format of a raw PCM stream.
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*/
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struct AudioFormat {
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/**
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* The sample rate in Hz. A better name for this attribute is
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* "frame rate", because technically, you have two samples per
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* frame in stereo sound.
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*/
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uint32_t sample_rate;
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/**
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* The format samples are stored in. See the #sample_format
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* enum for valid values.
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*/
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SampleFormat format;
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/**
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* The number of channels. Only mono (1) and stereo (2) are
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* fully supported currently.
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*/
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uint8_t channels;
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AudioFormat() = default;
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constexpr AudioFormat(uint32_t _sample_rate,
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SampleFormat _format, uint8_t _channels)
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:sample_rate(_sample_rate),
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format(_format), channels(_channels) {}
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static constexpr AudioFormat Undefined() {
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return AudioFormat(0, SampleFormat::UNDEFINED,0);
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}
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/**
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* Clears the #audio_format object, i.e. sets all attributes to an
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* undefined (invalid) value.
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*/
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void Clear() {
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sample_rate = 0;
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format = SampleFormat::UNDEFINED;
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channels = 0;
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}
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/**
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* Checks whether the object has a defined value.
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*/
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constexpr bool IsDefined() const {
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return sample_rate != 0;
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}
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/**
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* Checks whether the object is full, i.e. all attributes are
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* defined. This is more complete than IsDefined(), but
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* slower.
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*/
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constexpr bool IsFullyDefined() const {
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return sample_rate != 0 && format != SampleFormat::UNDEFINED &&
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channels != 0;
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}
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/**
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* Checks whether the object has at least one defined value.
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*/
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constexpr bool IsMaskDefined() const {
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return sample_rate != 0 || format != SampleFormat::UNDEFINED ||
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channels != 0;
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}
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bool IsValid() const;
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bool IsMaskValid() const;
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constexpr bool operator==(const AudioFormat other) const {
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return sample_rate == other.sample_rate &&
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format == other.format &&
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channels == other.channels;
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}
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constexpr bool operator!=(const AudioFormat other) const {
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return !(*this == other);
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}
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void ApplyMask(AudioFormat mask);
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/**
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* Returns the size of each (mono) sample in bytes.
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*/
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unsigned GetSampleSize() const;
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/**
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* Returns the size of each full frame in bytes.
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*/
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unsigned GetFrameSize() const;
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/**
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* Returns the floating point factor which converts a time
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* span to a storage size in bytes.
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*/
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double GetTimeToSize() const;
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};
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/**
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* Buffer for audio_format_string().
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*/
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struct audio_format_string {
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char buffer[24];
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};
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/**
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* Checks whether the sample rate is valid.
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*
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* @param sample_rate the sample rate in Hz
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*/
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static constexpr inline bool
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audio_valid_sample_rate(unsigned sample_rate)
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{
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return sample_rate > 0 && sample_rate < (1 << 30);
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}
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/**
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* Checks whether the sample format is valid.
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*
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* @param bits the number of significant bits per sample
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*/
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static inline bool
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audio_valid_sample_format(SampleFormat format)
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{
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switch (format) {
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case SampleFormat::S8:
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case SampleFormat::S16:
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case SampleFormat::S24_P32:
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case SampleFormat::S32:
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case SampleFormat::FLOAT:
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case SampleFormat::DSD:
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return true;
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case SampleFormat::UNDEFINED:
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break;
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}
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return false;
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}
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/**
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* Checks whether the number of channels is valid.
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*/
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static constexpr inline bool
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audio_valid_channel_count(unsigned channels)
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{
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return channels >= 1 && channels <= MAX_CHANNELS;
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}
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/**
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* Returns false if the format is not valid for playback with MPD.
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* This function performs some basic validity checks.
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*/
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inline bool
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AudioFormat::IsValid() const
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{
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return audio_valid_sample_rate(sample_rate) &&
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audio_valid_sample_format(format) &&
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audio_valid_channel_count(channels);
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}
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/**
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* Returns false if the format mask is not valid for playback with
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* MPD. This function performs some basic validity checks.
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*/
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inline bool
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AudioFormat::IsMaskValid() const
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{
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return (sample_rate == 0 ||
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audio_valid_sample_rate(sample_rate)) &&
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(format == SampleFormat::UNDEFINED ||
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audio_valid_sample_format(format)) &&
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(channels == 0 || audio_valid_channel_count(channels));
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}
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gcc_const
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static inline unsigned
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sample_format_size(SampleFormat format)
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{
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switch (format) {
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case SampleFormat::S8:
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return 1;
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case SampleFormat::S16:
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return 2;
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case SampleFormat::S24_P32:
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case SampleFormat::S32:
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case SampleFormat::FLOAT:
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return 4;
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case SampleFormat::DSD:
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/* each frame has 8 samples per channel */
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return 1;
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case SampleFormat::UNDEFINED:
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return 0;
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}
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assert(false);
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gcc_unreachable();
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}
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inline unsigned
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AudioFormat::GetSampleSize() const
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{
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return sample_format_size(format);
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}
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inline unsigned
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AudioFormat::GetFrameSize() const
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{
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return GetSampleSize() * channels;
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}
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inline double
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AudioFormat::GetTimeToSize() const
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{
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return sample_rate * GetFrameSize();
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}
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/**
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* Renders a #sample_format enum into a string, e.g. for printing it
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* in a log file.
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*
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* @param format a #sample_format enum value
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* @return the string
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*/
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gcc_pure gcc_malloc
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const char *
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sample_format_to_string(SampleFormat format);
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/**
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* Renders the #audio_format object into a string, e.g. for printing
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* it in a log file.
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*
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* @param af the #audio_format object
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* @param s a buffer to print into
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* @return the string, or nullptr if the #audio_format object is invalid
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*/
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gcc_pure gcc_malloc
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const char *
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audio_format_to_string(AudioFormat af,
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struct audio_format_string *s);
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#endif
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