snapshot()

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

(

uint64_t

frames

)

const

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

Frames that have already been overwritten come out black. 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 size, format and rate, or null if empty.

Definition at line 157 of file DynamicVideoStream.cpp.

{
    const uint64_t available = is_ring_mode()
        ? std::min<uint64_t>(m_write_head, m_ring_capacity)
        : m_write_head;
    const uint64_t count = std::min(frames, available);
 
    if (count == 0) {
        return nullptr;
    }
 
    auto copy = std::make_shared<DynamicVideoStream>(VideoStreamSpec {
        .width = m_width,
        .height = m_height,
        .format = m_format,
        .frame_rate = m_frame_rate });
    copy->ensure_capacity(count);
 
    const std::vector<uint8_t> blank(get_frame_byte_size(), 0);
 
    for (uint64_t index = m_write_head - count; index < m_write_head; ++index) {
        const auto pixels = get_frame_pixels(index);
        copy->append_frame(pixels.empty() ? std::span<const uint8_t>(blank) : pixels);
    }
 
    return copy;
}

References available, count, MayaFlux::Kakshya::VideoStreamContainer::get_frame_byte_size(), MayaFlux::Kakshya::VideoStreamContainer::get_frame_pixels(), index, MayaFlux::Kakshya::VideoStreamContainer::is_ring_mode(), MayaFlux::Kakshya::VideoStreamContainer::m_format, MayaFlux::Kakshya::VideoStreamContainer::m_frame_rate, MayaFlux::Kakshya::VideoStreamContainer::m_height, MayaFlux::Kakshya::VideoStreamContainer::m_ring_capacity, MayaFlux::Kakshya::VideoStreamContainer::m_width, m_write_head, pixels, and MayaFlux::Kakshya::VideoStreamSpec::width.

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