Method Decode

src/audio_generic.cpp:293–484

}

void GenericAudio::Decode(uint8_t* output_buffer, int buffer_length) {
	bool channel_active = false;
	float total_volume = 0;
	int samples_per_frame = buffer_length / output_format.channels / 2;

	assert(buffer_length > 0);

	if (sample_buffer.size() != (size_t)buffer_length) {
		sample_buffer.resize(buffer_length);
	}
	if (mixer_buffer.size() != (size_t)buffer_length) {
		mixer_buffer.resize(buffer_length);
	}
	scrap_buffer_size = samples_per_frame * output_format.channels * sizeof(uint32_t);
	if (scrap_buffer.size() != scrap_buffer_size) {
		scrap_buffer.resize(scrap_buffer_size);
	}
	std::fill(mixer_buffer.begin(), mixer_buffer.end(), '\0');

	for (unsigned i = 0; i < nr_of_bgm_channels + nr_of_se_channels; i++) {
		int read_bytes = 0;
		int channels = 0;
		int samplesize = 0;
		int frequency = 0;
		AudioDecoder::Format sampleformat;
		float volume;

		// Mix BGM and SE together;
		bool is_bgm_channel = i < nr_of_bgm_channels;
		bool channel_used = false;

		if (is_bgm_channel) {
			BgmChannel& currently_mixed_channel = BGM_Channels[i];
			float current_master_volume = cfg.music_volume.Get() / 100.0f;

			if (currently_mixed_channel.decoder && !currently_mixed_channel.paused) {
				if (currently_mixed_channel.stopped) {
					currently_mixed_channel.decoder.reset();
				} else {
					currently_mixed_channel.decoder->Update(std::chrono::microseconds(1000 * 1000 / 60));
					volume = current_master_volume * (currently_mixed_channel.decoder->GetVolume() / 100.0);
					currently_mixed_channel.decoder->GetFormat(frequency, sampleformat, channels);
					samplesize = AudioDecoder::GetSamplesizeForFormat(sampleformat);

					total_volume += volume;

					// determine how much data has to be read from this channel (but cap at the bounds of the scrap buffer)
					unsigned bytes_to_read = (samplesize * channels * samples_per_frame);
					bytes_to_read = (bytes_to_read < scrap_buffer_size) ? bytes_to_read : scrap_buffer_size;

					read_bytes = currently_mixed_channel.decoder->Decode(scrap_buffer.data(), bytes_to_read);

					if (read_bytes <= 0) {
						// An error occured when reading - the channel is faulty - discard
						currently_mixed_channel.decoder.reset();
						continue; // skip this loop run - there is nothing to mix
					}