hart_wavfile.hpp

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#pragma once
 
#include <memory>
#include <string>
 
#include "dependencies/choc/platform/choc_DisableAllWarnings.h"
#include "dependencies/dr_libs/dr_wav.h"
#include "dependencies/choc/platform/choc_ReenableAllWarnings.h"
 
#include "hart_exceptions.hpp"
#include "signals/hart_signal.hpp"
#include "hart_utils.hpp"                  // toAbsolutePath(), floatsNotEqual(), Loop
 
namespace hart
{
 
// TODO: Add "normalize" option?
// TODO: Add an entity that reuses wav data if a WavFile for a previously opened file gets instantiated
 
/// @brief Produces audio from a wav file
/// @details Original levels from the wav file are preserved
/// @ingroup Signals
template<typename SampleType>
class WavFile:
    public Signal<SampleType, WavFile<SampleType>>
{
public:
    /// @brief Creates a Signal that produces audio from a wav file
    /// @param filePath Path to a wav file
    /// Can be absolute or relative. If a relative path is used, it will resolve
    /// as relative to a data root path provided via respective CLI argument.
    /// @see HART_REQUIRES_DATA_PATH_ARG
    /// @param loop Indicates whether the signal should loop the audio or produce
    /// silence after wav file runs out of frames.
    WavFile (const std::string& filePath, Loop loop = Loop::no):
        m_filePath (filePath),
        m_loop (loop)
    {
        // TODO: Check if the file exists first
 
        drwav_uint64 numFrames;
        unsigned int numChannels;
        unsigned int wavSampleRateHz;
 
        float* pcmFrames = drwav_open_file_and_read_pcm_frames_f32 (
            toAbsolutePath (filePath).c_str(),
            &numChannels,
            &wavSampleRateHz,
            &numFrames,
            nullptr
            );
 
        if (pcmFrames == nullptr)
            HART_THROW_OR_RETURN_VOID (hart::IOError, std::string ("Could not read frames from the wav file"));
 
        m_wavFrames = std::make_shared<AudioBuffer<float>> (numChannels, numFrames);
 
        for (size_t frame = 0; frame < numFrames; ++frame)
            for (size_t channel = 0; channel < numChannels; ++channel)
                (*m_wavFrames)[channel][frame] = pcmFrames[frame * numChannels + channel];
 
        drwav_free (pcmFrames, nullptr);
 
        m_wavSampleRateHz = static_cast<double> (wavSampleRateHz);
        m_wavNumChannels = static_cast<size_t> (numChannels);
    }
 
    /// @copydoc Signal::supportsNumChannels()
    /// @note WavFile can only fill as much channels as there are in the wav file, or less.
    /// For instance, if the wav file is stereo, it can generate two channels (as they are),
    /// one channel (left, discarding right), but not three channels.
    bool supportsNumChannels (size_t numChannels) const override
    {
        return numChannels <= m_wavNumChannels;
    };
 
    void prepare (double sampleRateHz, size_t numOutputChannels, size_t /*maxBlockSizeFrames*/) override
    {
        // There are a few ovbvious cases where channel number mismatch can be gracefully resolved - perhaps in the future
        if (numOutputChannels != m_wavNumChannels)
            HART_THROW_OR_RETURN_VOID (hart::ChannelLayoutError, std::string ("Unexpected channel number"));
 
        if (floatsNotEqual (sampleRateHz, m_wavSampleRateHz))
            HART_THROW_OR_RETURN_VOID (hart::UnsupportedError, std::string ("Wav file is in different sampling rate, resampling not supported"));
    }
 
    void renderNextBlock (AudioBuffer<SampleType>& output) override
    {
        // TODO: Add support for number of channels different from the wav file
        // TODO: Add resampling
        const size_t numFrames = output.getNumFrames();
        size_t frameInOutputBuffer = 0;
        size_t frameInWavBuffer = m_wavOffsetFrames;
 
        while (m_wavOffsetFrames < m_wavFrames->getNumFrames() && frameInOutputBuffer < numFrames)
        {
            for (size_t channel = 0; channel < m_wavNumChannels; ++channel)
                output[channel][frameInOutputBuffer] = (*m_wavFrames)[channel][frameInWavBuffer];
 
            ++frameInOutputBuffer;
            ++frameInWavBuffer;
            ++m_wavOffsetFrames;
 
            if (m_loop == Loop::yes)
                m_wavOffsetFrames %= m_wavFrames->getNumFrames();
        }
 
        while (frameInOutputBuffer < numFrames)
        {
            hassert (m_loop == Loop::no);
 
            for (size_t channel = 0; channel < m_wavNumChannels; ++channel)
                output[channel][frameInOutputBuffer] = (SampleType) 0;
 
            ++frameInOutputBuffer;
        }
    }
 
    void reset() override
    {
        m_wavOffsetFrames = 0;
    }
 
    void represent (std::ostream& stream) const override
    {
        stream << "WavFile (\"" << m_filePath << (m_loop == Loop::yes ? "\", Loop::yes)" : "\", Loop::no)");
    }
 
private:
    const std::string m_filePath;
    const Loop m_loop;
    size_t m_wavNumChannels;
    double m_wavSampleRateHz;
    size_t m_wavOffsetFrames = 0;
    std::shared_ptr<AudioBuffer<float>> m_wavFrames;
};
 
HART_SIGNAL_DECLARE_ALIASES_FOR (WavFile)
 
}  // namespace hart