snapshot()

std::shared_ptr< DynamicSoundStream > MayaFlux::Kakshya::DynamicSoundStream::snapshot

(

uint64_t

frames

)

const

Copy the most recent frames into a new stream, oldest first.

Reads back from channel 0's write head, so it is meant for streams filled with append_frames. A ring is unrolled across its wrap; frames from before the first write are silence. The copy is independent of this stream.

Parameters

frames

Frames to keep, capped at the ring capacity, or at the frames written for a linear stream.

Returns

New stream with the same rate and channels, or null if empty.

Definition at line 256 of file DynamicSoundStream.cpp.

{
    const uint64_t head = get_write_head(0);
    const uint64_t available = m_is_circular ? m_circular_capacity : head;
    const uint64_t count = std::min(frames, available);
 
    if (count == 0) {
        return nullptr;
    }
 
    const uint64_t first = m_is_circular ? head + m_circular_capacity - count : head - count;
 
    std::vector<uint64_t> indices(count);
    for (uint64_t i = 0; i < count; ++i) {
        indices[i] = m_is_circular ? (first + i) % m_circular_capacity : first + i;
    }
 
    const uint64_t channels = get_num_channels();
    std::vector<double> taps(count * channels);
    gather_frames(indices, taps);
 
    auto copy = std::make_shared<DynamicSoundStream>(get_sample_rate(), get_num_channels());
 
    if (copy->get_structure().organization == OrganizationStrategy::INTERLEAVED) {
        copy->write_frames(std::vector<std::span<const double>> { taps }, 0);
        return copy;
    }
 
    std::vector<std::vector<double>> planar(channels, std::vector<double>(count));
    for (uint64_t i = 0; i < count; ++i) {
        for (uint64_t c = 0; c < channels; ++c) {
            planar[c][i] = taps[i * channels + c];
        }
    }
 
    std::vector<std::span<const double>> spans(planar.begin(), planar.end());
    copy->write_frames(std::move(spans), 0);
    return copy;
}

References available, channels, count, MayaFlux::Kakshya::SoundStreamContainer::gather_frames(), MayaFlux::Kakshya::SoundStreamContainer::get_num_channels(), MayaFlux::Kakshya::SoundStreamContainer::get_sample_rate(), get_write_head(), indices, MayaFlux::Kakshya::INTERLEAVED, m_circular_capacity, and m_is_circular.

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