src/audio/mp3_decoder.cpp - main - Mr.Stalin/FreeFT

src/audio/mp3_decoder.cpp
113 строк3 KB
Krzysztof Jakubowski
Fixed building of MP3 decoder under windows
11 янв 2025, 18:36
11 янв 2025, 18:36db4d145
// Copyright (C) Krzysztof Jakubowski <nadult@fastmail.fm>
// This file is part of FreeFT. See license.txt for details.

#include "audio/mp3_decoder.h"

#include <fwk/audio/sound.h>
#include <fwk/io/file_stream.h>

#include <mpg123.h>

namespace audio {

static int s_num_decoders = 0;

//TODO: silence errors
MP3Decoder::MP3Decoder(const string &file_name) {
	m_stream.emplace(std::move(fileLoader(file_name).get())); // TODO: pass it properly

	if(s_num_decoders++ == 0)
		mpg123_init();

	int ret = 0;
	auto handle = mpg123_new(0, &ret);
	if(!handle)
		FATAL("Error while creating mpg123 decoder");
	m_handle = handle;

	mpg123_open_feed(handle);
	//TODO: disable output
	mpg123_param(handle, MPG123_VERBOSE, 0.0, 0);

	m_is_finished = false;
	m_need_data = true;

	do {
		size_t size = 0;
		if(m_need_data) {
			PodVector<u8> input(min(4096, (int)(m_stream->size() - m_stream->pos())));
			m_stream->loadData(input);
			ret = mpg123_decode(handle, input.data(), input.size(), 0, 0, &size);
		} else {
			ret = mpg123_decode(handle, 0, 0, 0, 0, &size);
		}

		m_need_data = ret == MPG123_NEED_MORE;
	} while(ret != MPG123_ERR && ret != MPG123_NEW_FORMAT);

	if(ret == MPG123_ERR)
		FATAL("Error while opening mp3 file: %s\n", file_name.c_str());

	long rate;
	int enc;
	mpg123_getformat(handle, &rate, &m_num_channels, &enc);
	m_sample_rate = rate;

	if(enc != MPG123_ENC_SIGNED_16 || m_num_channels > 2)
		FATAL("Unsupported MP3 format (only 16-bit, with no more then 2 channels)");
}

MP3Decoder::~MP3Decoder() {
	if(m_handle)
		mpg123_delete((mpg123_handle *)m_handle);
	if(--s_num_decoders == 0)
		mpg123_exit();
}

bool MP3Decoder::decode(Sound &out, int max_size) {
	if(m_is_finished)
		return true;

	PodVector<char> temp(max_size);
	int out_pos = 0;
	auto handle = (mpg123_handle *)m_handle;

	int ret = 0;
	do {
		size_t size = 0;

		if(m_need_data) {
			int bytes_left = m_stream->size() - m_stream->pos();
			if(!bytes_left) {
				ret = MPG123_DONE;
				break;
			}
			PodVector<char> input(min(4096, bytes_left));

			m_stream->loadData(input);
			ret = mpg123_decode(handle, (u8 *)input.data(), input.size(),
								(u8 *)temp.data() + out_pos, max_size - out_pos, &size);
		} else {
			ret =
				mpg123_decode(handle, 0, 0, (u8 *)temp.data() + out_pos, max_size - out_pos, &size);
		}

		m_need_data = ret == MPG123_NEED_MORE;
		out_pos += size;
	} while(ret != MPG123_ERR && ret != MPG123_DONE && out_pos < max_size);

	m_is_finished = ret == MPG123_DONE || ret == MPG123_ERR;

	// TODO: this is bad
	temp.resize(out_pos);
	vector<char> out_data;
	temp.unsafeSwap(out_data);

	out = {std::move(out_data), {m_sample_rate, 16, m_num_channels == 2}};

	return m_is_finished;
}

int MP3Decoder::bytesPerSecond() const { return m_sample_rate * m_num_channels * 2; }

}