looper/subprojects/mpg123/doc/examples/mpg123_to_out123.c

/*
	mpg123_to_wav.c

	This is example code only sensible to be considered in the public domain.
	Initially written by Nicholas Humfrey.

	The most complicated part is about the choices to make about output format,
	and prepare for the unlikely case a bastard mp3 might file change it.
*/

#include <out123.h>
#include <mpg123.h>
#include <stdio.h>
#include <strings.h>

/** Print usage info. */
void usage(const char *cmd)
{
	printf("Usage: %s <input> [<driver> [<output> [encoding [buffersize]]]]\n"
	,	cmd);
	printf( "\nPlay MPEG audio from intput file to output file/device using\n"
		"specified out123 driver, sample encoding and buffer size optional.\n\n" );
	exit(99);
}

/** Free handles. */
void cleanup(mpg123_handle *mh, out123_handle *ao)
{
	out123_del(ao);
	/* It's really to late for error checks here;-) */
	mpg123_close(mh);
	mpg123_delete(mh);
}

/** The whole operation. */
int main(int argc, char *argv[])
{
	mpg123_handle *mh = NULL;
	out123_handle *ao = NULL;
	char *infile = NULL;
	char *driver = NULL;
	char *outfile = NULL;
	unsigned char* buffer = NULL;
	const char *encname;
	size_t buffer_size = 0;
	size_t done = 0;
	int channels = 0;
	int encoding = 0;
	int framesize = 1;
	long rate = 0;
	int  err  = MPG123_OK;
	off_t samples = 0;

	if(argc<2)
		usage(argv[0]);

	infile  = argv[1];
	if(argc >= 3)
		driver  = argv[2];
	if(argc >= 4)
		outfile = argv[3];
	printf("Input file:    %s\n", infile);
	printf("Output driver: %s\n", driver ? driver : "<nil> (default)");
	printf("Output file:   %s\n", outfile ? outfile : "<nil> (default)");

#if MPG123_API_VERSION < 46
	// Newer versions of the library don't need that anymore, but it is safe
	// to have the no-op call present for compatibility with old versions.
	err = mpg123_init();
#endif
	if(err != MPG123_OK || (mh = mpg123_new(NULL, &err)) == NULL)
	{
		fprintf(stderr, "Basic setup goes wrong: %s", mpg123_plain_strerror(err));
		cleanup(mh, ao);
		return -1;
	}

	ao = out123_new();
	if(!ao)
	{
		fprintf(stderr, "Cannot create output handle.\n");
		cleanup(mh, ao);
		return -1;
	}

	if(argc >= 5)
	{ /* Make mpg123 support the desired encoding only for all rates. */
		const long *rates;
		size_t rate_count;
		size_t i;
		int enc;
		/* If that is zero, you'll get the error soon enough from mpg123. */
		enc = out123_enc_byname(argv[4]);
		mpg123_format_none(mh);
		mpg123_rates(&rates, &rate_count);
		for(i=0; i<rate_count; ++i)
			mpg123_format(mh, rates[i], MPG123_MONO|MPG123_STEREO, enc);
	}

	/* Let mpg123 work with the file, that excludes MPG123_NEED_MORE messages. */
	if(    mpg123_open(mh, infile) != MPG123_OK
	/* Peek into track and get first output format. */
	    || mpg123_getformat(mh, &rate, &channels, &encoding) != MPG123_OK )
	{
		fprintf( stderr, "Trouble with mpg123: %s\n", mpg123_strerror(mh) );
		cleanup(mh, ao);
		return -1;
	}
	if(out123_open(ao, driver, outfile) != OUT123_OK)
	{
		fprintf(stderr, "Trouble with out123: %s\n", out123_strerror(ao));
		cleanup(mh, ao);
		return -1;
	}
	/* It makes no sense for that to give an error now. */
	out123_driver_info(ao, &driver, &outfile);
	printf("Effective output driver: %s\n", driver ? driver : "<nil> (default)");
	printf("Effective output file:   %s\n", outfile ? outfile : "<nil> (default)");

	/* Ensure that this output format will not change
	   (it might, when we allow it). */
	mpg123_format_none(mh);
	mpg123_format(mh, rate, channels, encoding);

	encname = out123_enc_name(encoding);
	printf( "Playing with %i channels and %li Hz, encoding %s.\n"
	,	channels, rate, encname ? encname : "???" );
	if(  out123_start(ao, rate, channels, encoding)
	  || out123_getformat(ao, NULL, NULL, NULL, &framesize) )
	{
		fprintf(stderr, "Cannot start output / get framesize: %s\n"
		,	out123_strerror(ao));
		cleanup(mh, ao);
		return -1;
	}

	/* Buffer could be almost any size here, mpg123_outblock() is just some
	   recommendation. The size should be a multiple of the PCM frame size. */
	buffer_size = argc >= 6 ? atol(argv[5]) : mpg123_outblock(mh);
	buffer = malloc( buffer_size );

	do
	{
		size_t played;
		err = mpg123_read( mh, buffer, buffer_size, &done );
		played = out123_play(ao, buffer, done);
		if(played != done)
		{
			fprintf(stderr
			,	"Warning: written less than gotten from libmpg123: %li != %li\n"
			,	(long)played, (long)done);
		}
		samples += played/framesize;
		/* We are not in feeder mode, so MPG123_OK, MPG123_ERR and
		   MPG123_NEW_FORMAT are the only possibilities.
		   We do not handle a new format, MPG123_DONE is the end... so
		   abort on anything not MPG123_OK. */
	} while (done && err==MPG123_OK);

	free(buffer);

	if(err != MPG123_DONE)
	fprintf( stderr, "Warning: Decoding ended prematurely because: %s\n",
	         err == MPG123_ERR ? mpg123_strerror(mh) : mpg123_plain_strerror(err) );

	printf("%li samples written.\n", (long)samples);
	cleanup(mh, ao);
	return 0;
}