owntone-server/src/scan-aac.c

/*
 * $Id$
 *
 * Copyright (C) 2003 Ron Pedde (ron@pedde.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 2 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, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#ifdef HAVE_CONFIG_H
#  include "config.h"
#endif

#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sys/time.h>

#include "err.h"
#include "mp3-scanner.h"
#include "scan-aac.h"

/* Forwards */
static time_t scan_aac_mac_to_unix_time(int t);

/**
 * Convert mac time to unix time (different epochs)
 *
 * @param t time since mac epoch
 * @returns time since unix epoch
 */
time_t scan_aac_mac_to_unix_time(int t) {
  struct timeval        tv;
  struct timezone       tz;
  
  gettimeofday(&tv, &tz);
  
  return (t - (365L * 66L * 24L * 60L * 60L + 17L * 60L * 60L * 24L) +
          (tz.tz_minuteswest * 60));
}

/**
 * Returns the offset of the atom specified by the given path or -1 if
 * not found. atom_path is a colon separated list of atoms specifying
 * a path from parent node to the target node. All paths must be specified
 * from the root.
 *
 * @param aac_fp the aac file being searched
 * @param atom_path the colon separated list of atoms
 * @param atom_length the size of the atom "drilled to"
 * @returns offset of the atom, or -1 if unsuccessful
 */
off_t scan_aac_drilltoatom(FILE *aac_fp,char *atom_path,
			   unsigned int *atom_length) {
    long          atom_offset;
    off_t         file_size;
    char          *cur_p, *end_p;
    char          atom_name[5];

    fseek(aac_fp, 0, SEEK_END);
    file_size = ftell(aac_fp);
    rewind(aac_fp);

    end_p = atom_path;
    while (*end_p != '\0') {
	    end_p++;
    }
    atom_name[4] = '\0';
    cur_p = atom_path;

    while (cur_p != NULL) {
	if ((end_p - cur_p) < 4) {
	    return -1;
	}
	strncpy(atom_name, cur_p, 4);
	atom_offset = scan_aac_findatom(aac_fp, file_size, 
					atom_name, atom_length);
	if (atom_offset == -1) {
	    return -1;
	}
	DPRINTF(E_SPAM,L_SCAN,"Found %s atom at off %ld.\n", 
		atom_name, ftell(aac_fp) - 8);

	cur_p = strchr(cur_p, ':');
	if (cur_p != NULL) {
	    cur_p++;

	    /* FIXME
	     * Hack to deal with atoms that have extra data in addition
	     * to having child atoms. This should be dealt in a better fashion
	     * than this (table with skip offsets or a real mp4 parser.) */
	    if (!strcmp(atom_name, "meta")) {
		fseek(aac_fp, 4, SEEK_CUR);
	    } else if (!strcmp(atom_name, "stsd")) {
		fseek(aac_fp, 8, SEEK_CUR);
	    } else if (!strcmp(atom_name, "mp4a")) {
		fseek(aac_fp, 28, SEEK_CUR);
	    }
	}
    }

    return ftell(aac_fp) - 8;
}

/**
 * Given a file, search for a particular aac atom.
 *
 * @param fin file handle of the open aac file
 * @param max_offset how far to search (probably size of container atom)
 * @param which_atom what atom name we are searching for
 * @param atom_size this will hold the size of the atom found
 */
long scan_aac_findatom(FILE *fin, long max_offset,
		       char *which_atom, unsigned int *atom_size) {
    long current_offset=0;
    int size;
    char atom[4];

    while(current_offset < max_offset) {
	if(fread((void*)&size,1,sizeof(int),fin) != sizeof(int))
	    return -1;

	size=ntohl(size);

	if(size <= 7) /* something not right */
	    return -1;

	if(fread(atom,1,4,fin) != 4) 
	    return -1;

	if(strncasecmp(atom,which_atom,4) == 0) {
	    *atom_size=size;
	    return current_offset;
	}

	fseek(fin,size-8,SEEK_CUR);
	current_offset+=size;
    }

    return -1;
}

/**
 * main aac scanning routing.
 *
 * @param filename file to scan
 * @param pmp3 pointer to the MP3FILE to fill with data
 * @returns FALSE if file should not be added to database, TRUE otherwise
 */
int scan_get_aacinfo(char *filename, MP3FILE *pmp3) {
    FILE *fin;
    long atom_offset;
    unsigned int atom_length;

    long current_offset=0;
    int current_size;
    char current_atom[4];
    char *current_data;
    unsigned short us_data;
    int genre;
    int len;

    int sample_size;
    int samples;
    unsigned int bit_rate;
    int ms;
    unsigned char buffer[2];
    int time = 0;


    if(!(fin=fopen(filename,"rb"))) {
	DPRINTF(E_INF,L_SCAN,"Cannot open file %s for reading\n",filename);
	return FALSE;
    }

    fseek(fin,0,SEEK_END);
    pmp3->file_size = ftell(fin);
    fseek(fin,0,SEEK_SET);


    atom_offset=scan_aac_drilltoatom(fin, "moov:udta:meta:ilst", &atom_length);
    if(atom_offset != -1) {
	/* found the tag section - need to walk through now */
      
	while(current_offset < atom_length) {
	    if(fread((void*)&current_size,1,sizeof(int),fin) != sizeof(int))
		break;
			
	    current_size=ntohl(current_size);
			
	    if(current_size <= 7) /* something not right */
		break;

	    if(fread(current_atom,1,4,fin) != 4) 
		break;
			
	    len=current_size-7;  /* for ill-formed too-short tags */
	    if(len < 22)
		len=22;

	    current_data=(char*)malloc(len);  /* extra byte */
	    memset(current_data,0x00,len);

	    if(fread(current_data,1,current_size-8,fin) != current_size-8) 
		break;

	    if(!memcmp(current_atom,"\xA9" "nam",4)) { /* Song name */
		pmp3->title=strdup((char*)&current_data[16]);
	    } else if(!memcmp(current_atom,"\xA9" "ART",4)) {
		pmp3->artist=strdup((char*)&current_data[16]);
	    } else if(!memcmp(current_atom,"\xA9" "alb",4)) {
		pmp3->album=strdup((char*)&current_data[16]);
	    } else if(!memcmp(current_atom,"\xA9" "cmt",4)) {
		pmp3->comment=strdup((char*)&current_data[16]);
	    } else if(!memcmp(current_atom,"\xA9" "wrt",4)) {
		pmp3->composer=strdup((char*)&current_data[16]);
	    } else if(!memcmp(current_atom,"\xA9" "grp",4)) {
		pmp3->grouping=strdup((char*)&current_data[16]);
	    } else if(!memcmp(current_atom,"\xA9" "gen",4)) {
		/* can this be a winamp genre??? */
		pmp3->genre=strdup((char*)&current_data[16]);
	    } else if(!memcmp(current_atom,"tmpo",4)) {
		us_data=*((unsigned short *)&current_data[16]);
		us_data=ntohs(us_data);
		pmp3->bpm=us_data;
	    } else if(!memcmp(current_atom,"trkn",4)) {
		us_data=*((unsigned short *)&current_data[18]);
		us_data=ntohs(us_data);

		pmp3->track=us_data;

		us_data=*((unsigned short *)&current_data[20]);
		us_data=ntohs(us_data);

		pmp3->total_tracks=us_data;
	    } else if(!memcmp(current_atom,"disk",4)) {
		us_data=*((unsigned short *)&current_data[18]);
		us_data=ntohs(us_data);

		pmp3->disc=us_data;

		us_data=*((unsigned short *)&current_data[20]);
		us_data=ntohs(us_data);

		pmp3->total_discs=us_data;
	    } else if(!memcmp(current_atom,"\xA9" "day",4)) {
		pmp3->year=atoi((char*)&current_data[16]);
	    } else if(!memcmp(current_atom,"gnre",4)) {
		genre=(int)(*((char*)&current_data[17]));
		genre--;
			    
		if((genre < 0) || (genre > WINAMP_GENRE_UNKNOWN))
		    genre=WINAMP_GENRE_UNKNOWN;

		pmp3->genre=strdup(scan_winamp_genre[genre]);
	    } else if (!memcmp(current_atom, "cpil", 4)) {
		pmp3->compilation = current_data[16];
	    }

	    free(current_data);
	    current_offset+=current_size;
	}
    }

    /* got the tag info, now let's get bitrate, etc */
    atom_offset = scan_aac_drilltoatom(fin, "moov:mvhd", &atom_length);
    if(atom_offset != -1) {
        fseek(fin, 4, SEEK_CUR);
        fread((void *)&time, sizeof(int), 1, fin);
        time = ntohl(time);
        pmp3->time_added = scan_aac_mac_to_unix_time(time);

        fread((void *)&time, sizeof(int), 1, fin);
        time = ntohl(time);
        pmp3->time_modified = scan_aac_mac_to_unix_time(time);
	fread((void*)&sample_size,1,sizeof(int),fin);
	fread((void*)&samples,1,sizeof(int),fin);

	sample_size=ntohl(sample_size);
	samples=ntohl(samples);

	/* avoid overflowing on large sample_sizes (90000) */
	ms=1000;
	while((ms > 9) && (!(sample_size % 10))) {
	    sample_size /= 10;
	    ms /= 10;
	}

	/* DWB: use ms time instead of sec */
	pmp3->song_length=(int)((samples * ms) / sample_size);
	DPRINTF(E_DBG,L_SCAN,"Song length: %d seconds\n", 
		pmp3->song_length / 1000);
    }

    pmp3->bitrate = 0;

    /* see if it is aac or alac */
    atom_offset = scan_aac_drilltoatom(fin,
				       "moov:trak:mdia:minf:stbl:stsd:alac", 
				       &atom_length);

    if(atom_offset != -1) {
	/* should we still pull samplerate, etc from the this atom? */
	if(pmp3->codectype) {
	    free(pmp3->codectype);
	}
	pmp3->codectype=strdup("alac");
    }

    /* Get the sample rate from the 'mp4a' atom (timescale). This is also
       found in the 'mdhd' atom which is a bit closer but we need to 
       navigate to the 'mp4a' atom anyways to get to the 'esds' atom. */
    atom_offset=scan_aac_drilltoatom(fin, 
				     "moov:trak:mdia:minf:stbl:stsd:mp4a", 
				     &atom_length);
    if (atom_offset != -1) {
	fseek(fin, atom_offset + 32, SEEK_SET);

	/* Timescale here seems to be 2 bytes here (the 2 bytes before it are
	 * "reserved") though the timescale in the 'mdhd' atom is 4. Not sure 
	 * how this is dealt with when sample rate goes higher than 64K. */
	fread(buffer, sizeof(unsigned char), 2, fin);

	pmp3->samplerate = (buffer[0] << 8) | (buffer[1]);

	/* Seek to end of atom. */
	fseek(fin, 2, SEEK_CUR);

	/* Get the bit rate from the 'esds' atom. We are already positioned
	   in the parent atom so just scan ahead. */
	atom_offset = scan_aac_findatom(fin, 
					atom_length-(ftell(fin)-atom_offset), 
					"esds", &atom_length);

	if (atom_offset != -1) {
	    /* Roku Soundbridge seems to believe anything above 320K is
	     * an ALAC encoded m4a.  We'll lie on their behalf.
	     */
	    fseek(fin, atom_offset + 22, SEEK_CUR);
	    fread((void *)&bit_rate, sizeof(unsigned int), 1, fin);
	    pmp3->bitrate = ntohl(bit_rate) / 1000;
	    DPRINTF(E_DBG,L_SCAN,"esds bitrate: %d\n",pmp3->bitrate);

	    if(pmp3->bitrate > 320) {
		pmp3->bitrate = 320;
	    }
	} else {
	    DPRINTF(E_DBG,L_SCAN, "Couldn't find 'esds' atom for bit rate.\n");
	}
    } else {
	DPRINTF(E_DBG,L_SCAN, "Couldn't find 'mp4a' atom for sample rate.\n");
    }

    /* Fallback if we can't find the info in the atoms. */
    if (pmp3->bitrate == 0) {
	/* calculate bitrate from song length... Kinda cheesy */
	DPRINTF(E_DBG,L_SCAN, "Guesstimating bit rate.\n");
	atom_offset=scan_aac_drilltoatom(fin,"mdat",&atom_length);
	if ((atom_offset != -1) && (pmp3->song_length)) {
	    pmp3->bitrate = atom_length / ((pmp3->song_length / 1000) * 128);
	}
    }

    fclose(fin);
    return TRUE;  /* we'll return as much as we got. */
}