mpg.c

/* 
 *  Squeezelite - lightweight headless squeezebox emulator
 *
 *  (c) Adrian Smith 2012-2015, triode1@btinternet.com
 *      Ralph Irving 2015-2024, ralph_irving@hotmail.com
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#include "squeezelite.h"

#include <mpg123.h>

#define READ_SIZE  512
#define WRITE_SIZE 32 * 1024

struct mpg {
	mpg123_handle *h;
	bool use16bit;
#if !LINKALL
	// mpg symbols to be dynamically loaded
	int (* mpg123_init)(void);
	int (* mpg123_feature)(const enum mpg123_feature_set);
	void (* mpg123_rates)(const long **, size_t *);
	int (* mpg123_format_none)(mpg123_handle *);
	int (* mpg123_format)(mpg123_handle *, long, int, int);
	mpg123_handle *(* mpg123_new)(const char*, int *);
	void (* mpg123_delete)(mpg123_handle *);
	int (* mpg123_open_feed)(mpg123_handle *);
	int (* mpg123_decode)(mpg123_handle *, const unsigned char *, size_t, unsigned char *, size_t, size_t *);
	int (* mpg123_getformat)(mpg123_handle *, long *, int *, int *);
	const char* (* mpg123_plain_strerror)(int);
#endif
};

static struct mpg *m;

extern log_level loglevel;

extern struct buffer *streambuf;
extern struct buffer *outputbuf;
extern struct streamstate stream;
extern struct outputstate output;
extern struct decodestate decode;
extern struct processstate process;

#define LOCK_S   mutex_lock(streambuf->mutex)
#define UNLOCK_S mutex_unlock(streambuf->mutex)
#define LOCK_O   mutex_lock(outputbuf->mutex)
#define UNLOCK_O mutex_unlock(outputbuf->mutex)
#if PROCESS
#define LOCK_O_direct   if (decode.direct) mutex_lock(outputbuf->mutex)
#define UNLOCK_O_direct if (decode.direct) mutex_unlock(outputbuf->mutex)
#define LOCK_O_not_direct   if (!decode.direct) mutex_lock(outputbuf->mutex)
#define UNLOCK_O_not_direct if (!decode.direct) mutex_unlock(outputbuf->mutex)
#define IF_DIRECT(x)    if (decode.direct) { x }
#define IF_PROCESS(x)   if (!decode.direct) { x }
#else
#define LOCK_O_direct   mutex_lock(outputbuf->mutex)
#define UNLOCK_O_direct mutex_unlock(outputbuf->mutex)
#define LOCK_O_not_direct
#define UNLOCK_O_not_direct
#define IF_DIRECT(x)    { x }
#define IF_PROCESS(x)
#endif

#if LINKALL
#define MPG123(h, fn, ...) (mpg123_ ## fn)(__VA_ARGS__)
#else
#define MPG123(h, fn, ...) (h)->mpg123_##fn(__VA_ARGS__)
#endif

static decode_state mpg_decode(void) {
	size_t bytes, space, size;
	int ret;
	u8_t *write_buf;

	LOCK_S;
	LOCK_O_direct;
	bytes = min(_buf_used(streambuf), _buf_cont_read(streambuf));

	IF_DIRECT(
		space = min(_buf_space(outputbuf), _buf_cont_write(outputbuf));
		write_buf = outputbuf->writep;
	);
	IF_PROCESS(
		space = process.max_in_frames;
		write_buf = process.inbuf;
	);

	bytes = min(bytes, READ_SIZE);
	space = min(space, WRITE_SIZE);

	if (m->use16bit) {
		space = (space / BYTES_PER_FRAME) * 4;
	}

	// only get the new stream information on first call so we can reset decode.direct appropriately
	if (decode.new_stream) {
		space = 0;
	}

	ret = MPG123(m, decode, m->h, streambuf->readp, bytes, write_buf, space, &size);

	if (ret == MPG123_NEW_FORMAT) {

		if (decode.new_stream) {
			long rate;
			int channels, enc;
			
			MPG123(m, getformat, m->h, &rate, &channels, &enc);
			
			LOG_INFO("setting track_start");
			LOCK_O_not_direct;
			output.next_sample_rate = decode_newstream(rate, output.supported_rates);
			IF_DSD( output.next_fmt = PCM; )
			output.track_start = outputbuf->writep;
			if (output.fade_mode) _checkfade(true);
			decode.new_stream = false;
			UNLOCK_O_not_direct;

		} else {
			LOG_WARN("format change mid stream - not supported");
		}
	}

	// expand 16bit output to 32bit samples
	if (m->use16bit) {
		s16_t *iptr;
		s32_t *optr;
		size_t count = size / 2;
		size = count * 4;
		iptr = (s16_t *)write_buf + count;
		optr = (s32_t *)write_buf + count;
		while (count--) {
			*--optr = *--iptr << 16;
		}
	}

	_buf_inc_readp(streambuf, bytes);

	IF_DIRECT(
		_buf_inc_writep(outputbuf, size);
	);
	IF_PROCESS(
		process.in_frames = size / BYTES_PER_FRAME;
	);

	UNLOCK_O_direct;

	LOG_SDEBUG("write %u frames", size / BYTES_PER_FRAME);

	if (ret == MPG123_DONE || (bytes == 0 && size == 0 && stream.state <= DISCONNECT)) {
		UNLOCK_S;
		LOG_INFO("stream complete");
		return DECODE_COMPLETE;
	}

	UNLOCK_S;

	if (ret == MPG123_ERR) {
		LOG_WARN("Error");
		return DECODE_COMPLETE;
	}

	// OK and NEED_MORE keep running
	return DECODE_RUNNING;
}

static void mpg_open(u8_t size, u8_t rate, u8_t chan, u8_t endianness) {
	int err;
	const long *list;
	size_t count, i;

	if (m->h) {
		MPG123(m, delete, m->h);
	}

	m->h = MPG123(m, new, NULL, &err);

	if (m->h == NULL) {
		LOG_WARN("new error: %s", MPG123(m, plain_strerror, err));
	}

	// restrict output to 32bit or 16bit signed 2 channel based on library capability
	MPG123(m, rates, &list, &count);
	MPG123(m, format_none, m->h);
	for (i = 0; i < count; i++) {
		MPG123(m, format, m->h, list[i], 2, m->use16bit ? MPG123_ENC_SIGNED_16 : MPG123_ENC_SIGNED_32);
	}

	err = MPG123(m, open_feed, m->h);

	if (err) {
		LOG_WARN("open feed error: %s", MPG123(m, plain_strerror, err));
	}
}

static void mpg_close(void) {
	MPG123(m, delete, m->h);
	m->h = NULL;
}

static bool load_mpg() {
#if !LINKALL
	void *handle = dlopen(LIBMPG, RTLD_NOW);
	char *err;

	if (!handle) {
		LOG_INFO("dlerror: %s", dlerror());
		return false;
	}
	
	m->mpg123_init = dlsym(handle, "mpg123_init");
	m->mpg123_feature = dlsym(handle, "mpg123_feature");
	m->mpg123_rates = dlsym(handle, "mpg123_rates");
	m->mpg123_format_none = dlsym(handle, "mpg123_format_none");
	m->mpg123_format = dlsym(handle, "mpg123_format");
	m->mpg123_new = dlsym(handle, "mpg123_new");
	m->mpg123_delete = dlsym(handle, "mpg123_delete");
	m->mpg123_open_feed = dlsym(handle, "mpg123_open_feed");
	m->mpg123_decode = dlsym(handle, "mpg123_decode");
	m->mpg123_getformat = dlsym(handle, "mpg123_getformat");
	m->mpg123_plain_strerror = dlsym(handle, "mpg123_plain_strerror");

	if ((err = dlerror()) != NULL) {
		LOG_INFO("dlerror: %s", err);		
		return false;
	}

	LOG_INFO("loaded "LIBMPG);
#endif

	return true;
}

struct codec *register_mpg(void) {
	static struct codec ret = { 
		'm',          // id
		"mp3",        // types
		READ_SIZE,    // min read
		WRITE_SIZE,   // min space
		mpg_open,     // open
		mpg_close,    // close
		mpg_decode,   // decode
	};

	m = malloc(sizeof(struct mpg));
	if (!m) {
		return NULL;
	}

	m->h = NULL;

	if (!load_mpg()) {
		return NULL;
	}

	MPG123(m, init);

	m->use16bit = MPG123(m, feature, MPG123_FEATURE_OUTPUT_32BIT);

	LOG_INFO("using mpg to decode mp3");
	return &ret;
}