source_player.hpp

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#pragma once

 
#include <pulp/audio/source.hpp>
 
#include <cstddef>
 
namespace pulp::audio {

class AudioSourcePlayer {
public:
    AudioSourcePlayer() = default;

    void set_source(AudioSource* source) {
        if (source_ == source) return;
        if (source_ && prepared_) source_->release_resources();
        source_ = source;
        prepared_ = false;
        last_sample_rate_ = 0.0;
        last_block_size_ = 0;
    }
 
    AudioSource* source() const { return source_; }

    void set_gain(float gain) { gain_ = gain; }
    float gain() const { return gain_; }

    void audio_callback(BufferView<float> out,
                         int num_samples,
                         double sample_rate) {
        if (num_samples <= 0 || out.num_channels() == 0) return;
        if (!source_) {
            fill_silence(out, num_samples);
            return;
        }
        if (!prepared_
            || sample_rate != last_sample_rate_
            || num_samples > last_block_size_) {
            source_->prepare_to_play(num_samples, sample_rate);
            last_sample_rate_ = sample_rate;
            last_block_size_ = num_samples;
            prepared_ = true;
        }
        source_->get_next_audio_block(out, /*start_sample=*/0, num_samples);
        if (gain_ != 1.0f) {
            for (std::size_t ch = 0; ch < out.num_channels(); ++ch) {
                float* ptr = out.channel_ptr(ch);
                for (int i = 0; i < num_samples; ++i) ptr[i] *= gain_;
            }
        }
    }

    void release() {
        if (source_ && prepared_) source_->release_resources();
        prepared_ = false;
        last_sample_rate_ = 0.0;
        last_block_size_ = 0;
    }
 
private:
    static void fill_silence(BufferView<float> out, int n) {
        for (std::size_t ch = 0; ch < out.num_channels(); ++ch) {
            float* ptr = out.channel_ptr(ch);
            for (int i = 0; i < n; ++i) ptr[i] = 0.0f;
        }
    }
 
    AudioSource* source_ = nullptr;
    float gain_ = 1.0f;
    bool prepared_ = false;
    double last_sample_rate_ = 0.0;
    int last_block_size_ = 0;
};
 
} // namespace pulp::audio