mirror of
https://github.com/badaix/snapcast
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103 lines
3 KiB
C++
103 lines
3 KiB
C++
/***
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This file is part of snapcast
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Copyright (C) 2014-2024 Johannes Pohl
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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 3 of the License, or
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(at your option) any later version.
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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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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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***/
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#pragma once
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// standard headers
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#include <cstdint>
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#include <string>
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/**
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* sample and frame as defined in alsa:
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* http://www.alsa-project.org/main/index.php/FramesPeriods
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* Say we want to work with a stereo, 16-bit, 44.1 KHz stream, one-way (meaning, either in playback or in capture direction). Then we have:
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* 'stereo' = number of channels: 2
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* 1 analog sample is represented with 16 bits = 2 bytes
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* 1 frame represents 1 analog sample from all channels; here we have 2 channels, and so:
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* 1 frame = (num_channels) * (1 sample in bytes) = (2 channels) * (2 bytes (16 bits) per sample) = 4 bytes (32 bits)
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* To sustain 2x 44.1 KHz analog rate - the system must be capable of data transfer rate, in Bytes/sec:
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* Bps_rate = (num_channels) * (1 sample in bytes) * (analog_rate) = (1 frame) * (analog_rate) = ( 2 channels ) * (2 bytes/sample) * (44100 samples/sec) =
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* 2*2*44100 = 176400 Bytes/sec (link to formula img)
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*/
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class SampleFormat
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{
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public:
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SampleFormat();
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SampleFormat(const std::string& format);
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SampleFormat(uint32_t rate, uint16_t bits, uint16_t channels);
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std::string toString() const;
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void setFormat(const std::string& format);
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void setFormat(uint32_t rate, uint16_t bits, uint16_t channels);
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bool isInitialized() const
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{
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return ((rate_ != 0) || (bits_ != 0) || (channels_ != 0));
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}
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uint32_t rate() const
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{
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return rate_;
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}
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uint16_t bits() const
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{
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return bits_;
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}
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uint16_t channels() const
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{
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return channels_;
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}
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// size in [bytes] of a single mono sample, e.g. 2 bytes (= 16 bits)
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uint16_t sampleSize() const
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{
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return sample_size_;
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}
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// size in [bytes] of a frame (sum of sample sizes = #channel*sampleSize), e.g. 4 bytes (= 2 channel * 16 bit)
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uint16_t frameSize() const
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{
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return frame_size_;
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}
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inline double msRate() const
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{
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return static_cast<double>(rate_) / 1000.;
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}
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inline double usRate() const
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{
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return static_cast<double>(rate_) / 1000000.;
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}
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inline double nsRate() const
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{
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return static_cast<double>(rate_) / 1000000000.;
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}
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private:
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uint16_t sample_size_;
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uint16_t frame_size_;
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uint32_t rate_;
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uint16_t bits_;
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uint16_t channels_;
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};
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