mpg123_to_wav.c

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/*
        mpg123_to_wav.c

        copyright 2007 by the mpg123 project - free software under the terms of the LGPL 2.1
        see COPYING and AUTHORS files in distribution or http://mpg123.org
        initially written by Nicholas Humfrey
*/

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


void usage()
{
        printf("Usage: mpg123_to_wav <input> <output> [s16|f32 [ <buffersize>]]\n");
        exit(99);
}

void cleanup(mpg123_handle *mh)
{
        /* It's really to late for error checks here;-) */
        mpg123_close(mh);
        mpg123_delete(mh);
        mpg123_exit();
}

int main(int argc, char *argv[])
{
        SNDFILE* sndfile = NULL;
        SF_INFO sfinfo;
        mpg123_handle *mh = NULL;
        unsigned char* buffer = NULL;
        size_t buffer_size = 0;
        size_t done = 0;
        int  channels = 0, encoding = 0;
        long rate = 0;
        int  err  = MPG123_OK;
        off_t samples = 0;

        if (argc<3) usage();
        printf( "Input file: %s\n", argv[1]);
        printf( "Output file: %s\n", argv[2]);
        
        err = mpg123_init();
        if(err != MPG123_OK || (mh = mpg123_new(NULL, &err)) == NULL)
        {
                fprintf(stderr, "Basic setup goes wrong: %s", mpg123_plain_strerror(err));
                cleanup(mh);
                return -1;
        }

        /* Simple hack to enable floating point output. */
        if(argc >= 4 && !strcmp(argv[3], "f32")) mpg123_param(mh, MPG123_ADD_FLAGS, MPG123_FORCE_FLOAT, 0.);

            /* Let mpg123 work with the file, that excludes MPG123_NEED_MORE messages. */
        if(    mpg123_open(mh, argv[1]) != 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);
                return -1;
        }

        if(encoding != MPG123_ENC_SIGNED_16 && encoding != MPG123_ENC_FLOAT_32)
        { /* Signed 16 is the default output format anyways; it would actually by only different if we forced it.
             So this check is here just for this explanation. */
                cleanup(mh);
                fprintf(stderr, "Bad encoding: 0x%x!\n", encoding);
                return -2;
        }
        /* Ensure that this output format will not change (it could, when we allow it). */
        mpg123_format_none(mh);
        mpg123_format(mh, rate, channels, encoding);

        bzero(&sfinfo, sizeof(sfinfo) );
        sfinfo.samplerate = rate;
        sfinfo.channels = channels;
        sfinfo.format = SF_FORMAT_WAV|(encoding == MPG123_ENC_SIGNED_16 ? SF_FORMAT_PCM_16 : SF_FORMAT_FLOAT);
        printf("Creating WAV with %i channels and %liHz.\n", channels, rate);

        sndfile = sf_open(argv[2], SFM_WRITE, &sfinfo);
        if(sndfile == NULL){ fprintf(stderr, "Cannot open output file!\n"); cleanup(mh); return -2; }

        /* Buffer could be almost any size here, mpg123_outblock() is just some recommendation.
           Important, especially for sndfile writing, is that the size is a multiple of sample size. */
        buffer_size = argc >= 5 ? atol(argv[4]) : mpg123_outblock(mh);
        buffer = malloc( buffer_size );

        do
        {
                sf_count_t more_samples;
                err = mpg123_read( mh, buffer, buffer_size, &done );
                more_samples = encoding == MPG123_ENC_SIGNED_16
                        ? sf_write_short(sndfile, (short*)buffer, done/sizeof(short))
                        : sf_write_float(sndfile, (float*)buffer, done/sizeof(float));
                if(more_samples < 0 || more_samples*mpg123_encsize(encoding) != done)
                {
                        fprintf(stderr, "Warning: Written number of samples does not match the byte count we got from libmpg123: %li != %li\n", (long)(more_samples*mpg123_encsize(encoding)), (long)done);
                }
                samples += more_samples;
                /* 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 (err==MPG123_OK);

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

        sf_close( sndfile );

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