Method ExtractSamplesFromReader

src/AudioWaveformer.cpp:213–372

}

AudioWaveformData AudioWaveformer::ExtractSamplesFromReader(ReaderBase* source_reader, int channel, int num_per_second, bool normalize) {
	AudioWaveformData data;

	if (!source_reader || num_per_second <= 0) {
		return data;
	}

	// Open reader (if needed)
	if (!source_reader->IsOpen()) {
		source_reader->Open();
	}

	const auto retry_delay = std::chrono::milliseconds(100);
	const auto max_wait_for_open = std::chrono::milliseconds(3000);

	auto get_frame_with_retry = [&](int64_t frame_number) -> std::shared_ptr<openshot::Frame> {
		std::chrono::steady_clock::time_point wait_start;
		bool waiting_for_open = false;
		while (true) {
			try {
				return source_reader->GetFrame(frame_number);
			} catch (const openshot::ReaderClosed&) {
				auto now = std::chrono::steady_clock::now();
				if (!waiting_for_open) {
					waiting_for_open = true;
					wait_start = now;
				} else if (now - wait_start >= max_wait_for_open) {
					throw;
				}

				std::this_thread::sleep_for(retry_delay);
			}
		}
	};

	int sample_rate = source_reader->info.sample_rate;
	if (sample_rate <= 0) {
		sample_rate = num_per_second;
	}
	int sample_divisor = sample_rate / num_per_second;
	if (sample_divisor <= 0) {
		sample_divisor = 1;
	}

	// Determine length of video frames (for waveform)
	int64_t reader_video_length = source_reader->info.video_length;
	if (reader_video_length < 0) {
		reader_video_length = 0;
	}
	float reader_duration = source_reader->info.duration;
	double fps_value = source_reader->info.fps.ToDouble();
	float frames_duration = 0.0f;
	if (reader_video_length > 0 && fps_value > 0.0) {
		frames_duration = static_cast<float>(reader_video_length / fps_value);
	}
	if (reader_duration <= 0.0f) {
		reader_duration = frames_duration;
	}