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/***
This file is part of snapcast
Copyright (C) 2014-2024 Johannes Pohl
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
***/
#pragma once
// standard headers
#include <cstdint>
#include <string>
/**
* sample and frame as defined in alsa:
* http://www.alsa-project.org/main/index.php/FramesPeriods
* 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:
* 'stereo' = number of channels: 2
* 1 analog sample is represented with 16 bits = 2 bytes
* 1 frame represents 1 analog sample from all channels; here we have 2 channels, and so:
* 1 frame = (num_channels) * (1 sample in bytes) = (2 channels) * (2 bytes (16 bits) per sample) = 4 bytes (32 bits)
* To sustain 2x 44.1 KHz analog rate - the system must be capable of data transfer rate, in Bytes/sec:
* Bps_rate = (num_channels) * (1 sample in bytes) * (analog_rate) = (1 frame) * (analog_rate) = ( 2 channels ) * (2 bytes/sample) * (44100 samples/sec) =
* 2*2*44100 = 176400 Bytes/sec (link to formula img)
*/
class SampleFormat
{
public:
SampleFormat();
SampleFormat(const std::string& format);
SampleFormat(uint32_t rate, uint16_t bits, uint16_t channels);
std::string toString() const;
void setFormat(const std::string& format);
void setFormat(uint32_t rate, uint16_t bits, uint16_t channels);
bool isInitialized() const
{
return ((rate_ != 0) || (bits_ != 0) || (channels_ != 0));
}
uint32_t rate() const
{
return rate_;
}
uint16_t bits() const
{
return bits_;
}
uint16_t channels() const
{
return channels_;
}
// size in [bytes] of a single mono sample, e.g. 2 bytes (= 16 bits)
uint16_t sampleSize() const
{
return sample_size_;
}
// size in [bytes] of a frame (sum of sample sizes = #channel*sampleSize), e.g. 4 bytes (= 2 channel * 16 bit)
uint16_t frameSize() const
{
return frame_size_;
}
inline double msRate() const
{
return static_cast<double>(rate_) / 1000.;
}
inline double usRate() const
{
return static_cast<double>(rate_) / 1000000.;
}
inline double nsRate() const
{
return static_cast<double>(rate_) / 1000000000.;
}
private:
uint16_t sample_size_;
uint16_t frame_size_;
uint32_t rate_;
uint16_t bits_;
uint16_t channels_;
};
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