libopenshot/src/AudioResampler.cpp

/**
 * @file
 * @brief Source file for AudioResampler class
 * @author Jonathan Thomas <jonathan@openshot.org>
 *
 * @ref License
 */

/* LICENSE
 *
 * Copyright (c) 2008-2019 OpenShot Studios, LLC
 * <http://www.openshotstudios.com/>. This file is part of
 * OpenShot Library (libopenshot), an open-source project dedicated to
 * delivering high quality video editing and animation solutions to the
 * world. For more information visit <http://www.openshot.org/>.
 *
 * OpenShot Library (libopenshot) is free software: you can redistribute it
 * and/or modify it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * OpenShot Library (libopenshot) is distributed in the hope that it will be
 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with OpenShot Library. If not, see <http://www.gnu.org/licenses/>.
 */

#include "../include/AudioResampler.h"

using namespace std;
using namespace openshot;

// Default constructor, max frames to cache is 20 // resample_source(NULL), buffer_source(NULL), num_of_samples(0), new_num_of_samples(0), dest_ratio(0), source_ratio(0), resampled_buffer(NULL), isPrepared(false)
AudioResampler::AudioResampler()
{
	resample_source = NULL;
	buffer_source = NULL;
	num_of_samples = 0;
	new_num_of_samples = 0;
	dest_ratio = 0;
	source_ratio = 0;
	resampled_buffer = NULL;
	isPrepared = false;

	// Init buffer source
	buffer_source = new AudioBufferSource(buffer);

	// Init resampling source
	resample_source = new ResamplingAudioSource(buffer_source, false, 2);

	// Init resampled buffer
	resampled_buffer = new AudioSampleBuffer(2, 1);
	resampled_buffer->clear();

	// Init callback buffer
	resample_callback_buffer.buffer = resampled_buffer;
	resample_callback_buffer.numSamples = 1;
	resample_callback_buffer.startSample = 0;
}

// Descructor
AudioResampler::~AudioResampler()
{
	// Clean up
	if (buffer_source)
		delete buffer_source;
	if (resample_source)
		delete resample_source;
	if (resampled_buffer)
		delete resampled_buffer;
}

// Sets the audio buffer and updates the key settings
void AudioResampler::SetBuffer(AudioSampleBuffer *new_buffer, double sample_rate, double new_sample_rate)
{
	if (sample_rate <= 0)
		sample_rate = 44100;
	if (new_sample_rate <= 0)
		new_sample_rate = 44100;

	// Set the sample ratio (the ratio of sample rate change)
	source_ratio = sample_rate / new_sample_rate;

	// Call SetBuffer with ratio
	SetBuffer(new_buffer, source_ratio);
}

// Sets the audio buffer and key settings
void AudioResampler::SetBuffer(AudioSampleBuffer *new_buffer, double ratio)
{
	// Update buffer & buffer source
	buffer = new_buffer;
	buffer_source->setBuffer(buffer);

	// Set the sample ratio (the ratio of sample rate change)
	source_ratio = ratio;
	dest_ratio = 1.0 / ratio;
	num_of_samples = buffer->getNumSamples();
	new_num_of_samples = round(num_of_samples * dest_ratio) - 1;

	// Set resample ratio
	resample_source->setResamplingRatio(source_ratio);

	// Prepare to play resample source
	if (!isPrepared)
	{
		// Prepare to play the audio sources (and set the # of samples per chunk to a little more than expected)
		resample_source->prepareToPlay(num_of_samples + 10, 0);
		isPrepared = true;
	}

	// Resize buffer for the newly resampled data
	resampled_buffer->setSize(buffer->getNumChannels(), new_num_of_samples, true, true, true);
	resample_callback_buffer.numSamples = new_num_of_samples;
	resample_callback_buffer.startSample = 0;
	resample_callback_buffer.clearActiveBufferRegion();
}

// Get the resampled audio buffer
AudioSampleBuffer* AudioResampler::GetResampledBuffer()
{
	// Resample the current frame's audio buffer (into the temp callback buffer)
	resample_source->getNextAudioBlock(resample_callback_buffer);

	// Return buffer pointer to this newly resampled buffer
	return resampled_buffer;
}