owntone-server/src/scan-mp3.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 <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <id3tag.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

#include "conf.h"
#include "daapd.h"
#include "err.h"
#include "mp3-scanner.h"

#if __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ > 4)
# define _PACKED __attribute((packed))
#else
# define _PACKED
#endif

/**
 * Struct to keep info about the information gleaned from
 * the mp3 frame header.
 */
typedef struct tag_scan_frameinfo {
    int layer;               /**< 1, 2, or 3, representing Layer I, II, and III */
    int bitrate;             /**< Bitrate in kbps (128, 64, etc) */
    int samplerate;          /**< Samplerate (e.g. 44100) */
    int stereo;              /**< Any kind of stereo.. joint, dual mono, etc */

    int frame_length;        /**< Frame length in bytes - calculated */
    int crc_protected;       /**< Is the frame crc protected? */
    int samples_per_frame;   /**< Samples per frame - calculated field */
    int padding;             /**< Whether or not there is a padding sample */
    int xing_offset;         /**< Where the xing header should be relative to end of hdr */
    int number_of_frames;    /**< Number of frames in the song */

    int frame_offset;        /**< Where this frame was found */

    double version;          /**< MPEG version (e.g. 2.0, 2.5, 1.0) */

    int is_valid;
} SCAN_FRAMEINFO;

/* This should take take of win32 and gcc, any others? */
#pragma pack(1)
typedef struct tag_scan_id3header {
    unsigned char id[3];
    unsigned char version[2];
    unsigned char flags;
    unsigned char size[4];
} _PACKED SCAN_ID3HEADER;
#pragma pack()

/*
 * Globals
 */
int scan_br_table[5][16] = {
    { 0,32,64,96,128,160,192,224,256,288,320,352,384,416,448,0 }, /* MPEG1, Layer 1 */
    { 0,32,48,56,64,80,96,112,128,160,192,224,256,320,384,0 },    /* MPEG1, Layer 2 */
    { 0,32,40,48,56,64,80,96,112,128,160,192,224,256,320,0 },     /* MPEG1, Layer 3 */
    { 0,32,48,56,64,80,96,112,128,144,160,176,192,224,256,0 },    /* MPEG2/2.5, Layer 1 */
    { 0,8,16,24,32,40,48,56,64,80,96,112,128,144,160,0 }          /* MPEG2/2.5, Layer 2/3 */
};

int scan_sample_table[3][4] = {
    { 44100, 48000, 32000, 0 },  /* MPEG 1 */
    { 22050, 24000, 16000, 0 },  /* MPEG 2 */
    { 11025, 12000, 8000, 0 }    /* MPEG 2.5 */
};

char *scan_winamp_genre[] = {
    "Blues",              // 0
    "Classic Rock",
    "Country",
    "Dance",
    "Disco",
    "Funk",               // 5
    "Grunge",
    "Hip-Hop",
    "Jazz",
    "Metal",
    "New Age",            // 10
    "Oldies",
    "Other",
    "Pop",
    "R&B",
    "Rap",                // 15
    "Reggae",
    "Rock",
    "Techno",
    "Industrial",
    "Alternative",        // 20
    "Ska",
    "Death Metal",
    "Pranks",
    "Soundtrack",
    "Euro-Techno",        // 25
    "Ambient",
    "Trip-Hop",
    "Vocal",
    "Jazz+Funk",
    "Fusion",             // 30
    "Trance",
    "Classical",
    "Instrumental",
    "Acid",
    "House",              // 35
    "Game",
    "Sound Clip",
    "Gospel",
    "Noise",
    "AlternRock",         // 40
    "Bass",
    "Soul",
    "Punk",
    "Space",
    "Meditative",         // 45
    "Instrumental Pop",
    "Instrumental Rock",
    "Ethnic",
    "Gothic",
    "Darkwave",           // 50
    "Techno-Industrial",
    "Electronic",
    "Pop-Folk",
    "Eurodance",
    "Dream",              // 55
    "Southern Rock",
    "Comedy",
    "Cult",
    "Gangsta",
    "Top 40",             // 60
    "Christian Rap",
    "Pop/Funk",
    "Jungle",
    "Native American",
    "Cabaret",            // 65
    "New Wave",
    "Psychadelic",
    "Rave",
    "Showtunes",
    "Trailer",            // 70
    "Lo-Fi",
    "Tribal",
    "Acid Punk",
    "Acid Jazz",
    "Polka",              // 75
    "Retro",
    "Musical",
    "Rock & Roll",
    "Hard Rock",
    "Folk",               // 80
    "Folk/Rock",
    "National folk",
    "Swing",
    "Fast-fusion",
    "Bebob",              // 85
    "Latin",
    "Revival",
    "Celtic",
    "Bluegrass",
    "Avantgarde",         // 90
    "Gothic Rock",
    "Progressive Rock",
    "Psychedelic Rock",
    "Symphonic Rock",
    "Slow Rock",          // 95
    "Big Band",
    "Chorus",
    "Easy Listening",
    "Acoustic",
    "Humour",             // 100
    "Speech",
    "Chanson",
    "Opera",
    "Chamber Music",
    "Sonata",             // 105
    "Symphony",
    "Booty Bass",
    "Primus",
    "Porn Groove",
    "Satire",             // 110
    "Slow Jam",
    "Club",
    "Tango",
    "Samba",
    "Folklore",           // 115
    "Ballad",
    "Powder Ballad",
    "Rhythmic Soul",
    "Freestyle",
    "Duet",               // 120
    "Punk Rock",
    "Drum Solo",
    "A Capella",
    "Euro-House",
    "Dance Hall",         // 125
    "Goa",
    "Drum & Bass",
    "Club House",
    "Hardcore",
    "Terror",             // 130
    "Indie",
    "BritPop",
    "NegerPunk",
    "Polsk Punk",
    "Beat",               // 135
    "Christian Gangsta",
    "Heavy Metal",
    "Black Metal",
    "Crossover",
    "Contemporary C",     // 140
    "Christian Rock",
    "Merengue",
    "Salsa",
    "Thrash Metal",
    "Anime",              // 145
    "JPop",
    "SynthPop",
    "Unknown"
};

/* Forwards */
static int scan_mp3_get_mp3tags(char *file, MP3FILE *pmp3);
static int scan_mp3_get_mp3fileinfo(char *file, MP3FILE *pmp3);
static int scan_mp3_decode_mp3_frame(unsigned char *frame,SCAN_FRAMEINFO *pfi);
static void scan_mp3_get_average_bitrate(FILE *infile, SCAN_FRAMEINFO *pfi);
static int scan_mp3_is_numeric(char *str);
static void scan_mp3_get_frame_count(FILE *infile, SCAN_FRAMEINFO *pfi);


/**
 * main entrypoint for the scanner
 *
 * @param filename file to scan
 * @param pmp3 MP3FILE structure to fill
 * @returns TRUE if file should be added to DB, FALSE otherwise
 */
int scan_get_mp3info(char *filename, MP3FILE *pmp3) {
    if(scan_mp3_get_mp3tags(filename, pmp3))
        return scan_mp3_get_mp3fileinfo(filename,pmp3);
    return FALSE;
}

/**
 * decide if a string is numeric or not...
 *
 * @param str string to evaluate
 * @returns 1 if number, 0 otherwise
 */
int scan_mp3_is_numeric(char *str) {
    char *ptr=str;

    while(*ptr) {
        if(!isdigit(*ptr))
            return 0;
        ptr++;
    }
    return 1;
}

int scan_mp3_get_mp3tags(char *file, MP3FILE *pmp3) {
    struct id3_file *pid3file;
    struct id3_tag *pid3tag;
    struct id3_frame *pid3frame;
    int err;
    int index;
    int used;
    int mp3_fd;
    char *utf8_text;
    int genre=WINAMP_GENRE_UNKNOWN;
    int have_utf8;
    int have_text;
    id3_ucs4_t const *native_text;
    char *tmp;
    int got_numeric_genre;
    int rating;

    mp3_fd = open(file,O_RDONLY);
    if(mp3_fd == -1) {
        DPRINTF(E_WARN,L_SCAN,"Cannot open %s\n",file);
        return FALSE;
    }
         
    pid3file=id3_file_fdopen(mp3_fd,ID3_FILE_MODE_READONLY);
    if(!pid3file) {
        DPRINTF(E_WARN,L_SCAN,"Cannot open %s\n",file);
        return FALSE;
    }

    pid3tag=id3_file_tag(pid3file);

    if(!pid3tag) {
        err=errno;
        id3_file_close(pid3file);
        errno=err;
        DPRINTF(E_WARN,L_SCAN,"Cannot get ID3 tag for %s\n",file);
        return FALSE;
    }

    DPRINTF(E_SPAM,L_SCAN,"Starting mp3 tag scan\n");

    index=0;
    while((pid3frame=id3_tag_findframe(pid3tag,"",index))) {
        used=0;
        utf8_text=NULL;
        native_text=NULL;
        have_utf8=0;
        have_text=0;

        DPRINTF(E_SPAM,L_SCAN,"Found tag %s\n",pid3frame->id);

        if(!strcmp(pid3frame->id,"YTCP")) { /* for id3v2.2 */
            pmp3->compilation = 1;
            DPRINTF(E_DBG,L_SCAN,"Compilation: %d\n", pmp3->compilation);
        }

        if(((pid3frame->id[0] == 'T')||(strcmp(pid3frame->id,"COMM")==0)) &&
           (id3_field_getnstrings(&pid3frame->fields[1])))
            have_text=1;

        if(have_text) {
            native_text=id3_field_getstrings(&pid3frame->fields[1],0);

            if(native_text) {
                /* FIXME: I didn't understand what was happening here.
                 * this should really be a switch to evaluate latin1
                 * tags as native codepage.  Not only is this hackish,
                 * it's just plain wrong.
                 */
                have_utf8=1;
                if(conf_get_int("general","latin1_tags",0)) {
                    utf8_text=(char *)id3_ucs4_latin1duplicate(native_text);
                } else {
                    utf8_text=(char *)id3_ucs4_utf8duplicate(native_text);
                }

                if(!strcmp(pid3frame->id,"TIT2")) { /* Title */
                    used=1;
                    pmp3->title = utf8_text;
                    DPRINTF(E_DBG,L_SCAN," Title: %s\n",utf8_text);
                } else if(!strcmp(pid3frame->id,"TPE1")) {
                    used=1;
                    pmp3->artist = utf8_text;
                    DPRINTF(E_DBG,L_SCAN," Artist: %s\n",utf8_text);
                } else if(!strcmp(pid3frame->id,"TALB")) {
                    used=1;
                    pmp3->album = utf8_text;
                    DPRINTF(E_DBG,L_SCAN," Album: %s\n",utf8_text);
                } else if(!strcmp(pid3frame->id,"TCOM")) {
                    used=1;
                    pmp3->composer = utf8_text;
                    DPRINTF(E_DBG,L_SCAN," Composer: %s\n",utf8_text);
                } else if(!strcmp(pid3frame->id,"TIT1")) {
                    used=1;
                    pmp3->grouping = utf8_text;
                    DPRINTF(E_DBG,L_SCAN," Grouping: %s\n",utf8_text);
                } else if(!strcmp(pid3frame->id,"TPE2")) {
                    used=1;
                    pmp3->orchestra = utf8_text;
                    DPRINTF(E_DBG,L_SCAN," Orchestra: %s\n",utf8_text);
                } else if(!strcmp(pid3frame->id,"TPE3")) {
                    used=1;
                    pmp3->conductor = utf8_text;
                    DPRINTF(E_DBG,L_SCAN," Conductor: %s\n",utf8_text);
                } else if(!strcmp(pid3frame->id,"TCON")) {
                    used=1;
                    pmp3->genre = utf8_text;
                    got_numeric_genre=0;
                    DPRINTF(E_DBG,L_SCAN," Genre: %s\n",utf8_text);
                    if(pmp3->genre) {
                        if(!strlen(pmp3->genre)) {
                            genre=WINAMP_GENRE_UNKNOWN;
                            got_numeric_genre=1;
                        } else if (scan_mp3_is_numeric(pmp3->genre)) {
                            genre=atoi(pmp3->genre);
                            got_numeric_genre=1;
                        } else if ((pmp3->genre[0] == '(') && (isdigit(pmp3->genre[1]))) {
                            genre=atoi((char*)&pmp3->genre[1]);
                            got_numeric_genre=1;
                        }

                        if(got_numeric_genre) {
                            if((genre < 0) || (genre > WINAMP_GENRE_UNKNOWN))
                                genre=WINAMP_GENRE_UNKNOWN;
                            free(pmp3->genre);
                            pmp3->genre=strdup(scan_winamp_genre[genre]);
                        }
                    }
                } else if(!strcmp(pid3frame->id,"COMM")) {
                    used=1;
                    pmp3->comment = utf8_text;
                    DPRINTF(E_DBG,L_SCAN," Comment: %s\n",pmp3->comment);
                } else if(!strcmp(pid3frame->id,"TPOS")) {
                    tmp=utf8_text;
                    strsep(&tmp,"/");
                    if(tmp) {
                        pmp3->total_discs=atoi(tmp);
                    }
                    pmp3->disc=atoi(utf8_text);
                    DPRINTF(E_DBG,L_SCAN," Disc %d of %d\n",pmp3->disc,pmp3->total_discs);
                } else if(!strcmp(pid3frame->id,"TRCK")) {
                    tmp=utf8_text;
                    strsep(&tmp,"/");
                    if(tmp) {
                        pmp3->total_tracks=atoi(tmp);
                    }
                    pmp3->track=atoi(utf8_text);
                    DPRINTF(E_DBG,L_SCAN," Track %d of %d\n",pmp3->track,pmp3->total_tracks);
                } else if(!strcmp(pid3frame->id,"TDRC")) {
                    pmp3->year = atoi(utf8_text);
                    DPRINTF(E_DBG,L_SCAN," Year: %d\n",pmp3->year);
                } else if(!strcmp(pid3frame->id,"TLEN")) {
                    pmp3->song_length = atoi(utf8_text); /* now in ms */
                    DPRINTF(E_DBG,L_SCAN," Length: %d\n", pmp3->song_length);
                } else if(!strcmp(pid3frame->id,"TBPM")) {
                    pmp3->bpm = atoi(utf8_text);
                    DPRINTF(E_DBG,L_SCAN,"BPM: %d\n", pmp3->bpm);
                } else if(!strcmp(pid3frame->id,"TCMP")) { /* for id3v2.3 */
                    pmp3->compilation = (char)atoi(utf8_text);
                    DPRINTF(E_DBG,L_SCAN,"Compilation: %d\n", pmp3->compilation);
                }
            }
        }

        /* can check for non-text tags here */
        if((!used) && (have_utf8) && (utf8_text))
            free(utf8_text);

        if((!strcmp(pid3frame->id,"POPM")) && (pid3frame->nfields == 3)) {
            rating = id3_field_getint(&pid3frame->fields[1]);
            if(rating >= 0x01)
                pmp3->rating = 20;
            if(rating >= 0x40)
                pmp3->rating = 40;
            if(rating >= 0x80)
                pmp3->rating = 60;
            if(rating >= 0xC4)
                pmp3->rating = 80;
            if(rating >= 0xFF)
                pmp3->rating = 100;
        }


        /* v2 COMM tags are a bit different than v1 */
        if((!strcmp(pid3frame->id,"COMM")) && (pid3frame->nfields == 4)) {
            /* Make sure it isn't a application-specific comment...
             * This currently includes the following:
             *
             * iTunes_CDDB_IDs
             * iTunNORM
             *
             * If other apps stuff crap into comment fields, then we'll ignore them
             * here.
             */
            native_text=id3_field_getstring(&pid3frame->fields[2]);
            if(native_text) {
                utf8_text=(char*)id3_ucs4_utf8duplicate(native_text);
                if((utf8_text) && (strncasecmp(utf8_text,"iTun",4) != 0)) {
                    /* it's a real comment */
                    if(utf8_text)
                        free(utf8_text);

                    native_text=id3_field_getfullstring(&pid3frame->fields[3]);
                    if(native_text) {
                        if(pmp3->comment)
                            free(pmp3->comment);
                        utf8_text=(char*)id3_ucs4_utf8duplicate(native_text);
                        if(utf8_text) {
                            pmp3->comment=utf8_text;
                        }
                    }
                } else {
                    if(utf8_text)
                        free(utf8_text);
                }
            }
        }

        index++;
    }

    id3_file_close(pid3file);
    DPRINTF(E_DBG,L_SCAN,"Got id3 tag successfully\n");
    return TRUE;
}

/**
 * Decode an mp3 frame header.  Determine layer, bitrate,
 * samplerate, etc, and fill in the passed structure.
 *
 * @param frame 4 byte mp3 frame header
 * @param pfi pointer to an allocated SCAN_FRAMEINFO struct
 * @return 0 on success (valid frame), -1 otherwise
 */
int scan_mp3_decode_mp3_frame(unsigned char *frame, SCAN_FRAMEINFO *pfi) {
    int ver;
    int layer_index;
    int sample_index;
    int bitrate_index;
    int samplerate_index;

    if((frame[0] != 0xFF) || (frame[1] < 224)) {
        pfi->is_valid=0;
        return -1;
    }

    ver=(frame[1] & 0x18) >> 3;
    pfi->layer = 4 - ((frame[1] & 0x6) >> 1);

    layer_index=-1;
    sample_index=-1;

    switch(ver) {
    case 0:
        pfi->version = 2.5;
        sample_index=2;
        if(pfi->layer == 1)
            layer_index = 3;
        if((pfi->layer == 2) || (pfi->layer == 3))
            layer_index = 4;
        break;
    case 2:
        pfi->version = 2.0;
        sample_index=1;
        if(pfi->layer == 1)
            layer_index=3;
        if((pfi->layer == 2) || (pfi->layer == 3))
            layer_index=4;
        break;
    case 3:
        pfi->version = 1.0;
        sample_index=0;
        if(pfi->layer == 1)
            layer_index = 0;
        if(pfi->layer == 2)
            layer_index = 1;
        if(pfi->layer == 3)
            layer_index = 2;
        break;
    }

    if((layer_index < 0) || (layer_index > 4)) {
        pfi->is_valid=0;
        return -1;
    }

    if((sample_index < 0) || (sample_index > 2)) {
        pfi->is_valid=0;
        return -1;
    }

    if(pfi->layer==1) pfi->samples_per_frame=384;
    if(pfi->layer==2) pfi->samples_per_frame=1152;
    if(pfi->layer==3) {
        if(pfi->version == 1.0) {
            pfi->samples_per_frame=1152;
        } else {
            pfi->samples_per_frame=576;
        }
    }

    bitrate_index=(frame[2] & 0xF0) >> 4;
    samplerate_index=(frame[2] & 0x0C) >> 2;

    if((bitrate_index == 0xF) || (bitrate_index==0x0)) {
        pfi->is_valid=0;
        return -1;
    }

    if(samplerate_index == 3) {
        pfi->is_valid=0;
        return -1;
    }

    pfi->bitrate = scan_br_table[layer_index][bitrate_index];
    pfi->samplerate = scan_sample_table[sample_index][samplerate_index];

    if((frame[3] & 0xC0 >> 6) == 3)
        pfi->stereo = 0;
    else
        pfi->stereo = 1;

    if(frame[2] & 0x02) { /* Padding bit set */
        pfi->padding=1;
    } else {
        pfi->padding=0;
    }

    if(pfi->version == 1.0) {
        if(pfi->stereo) {
            pfi->xing_offset=32;
        } else {
            pfi->xing_offset=17;
        }
    } else {
        if(pfi->stereo) {
            pfi->xing_offset=17;
        } else {
            pfi->xing_offset=9;
        }
    }

    pfi->crc_protected=(frame[1] & 0xFE);

    if(pfi->layer == 1) {
        pfi->frame_length = (12 * pfi->bitrate * 1000 / pfi->samplerate + pfi->padding) * 4;
    } else {
        pfi->frame_length = 144 * pfi->bitrate * 1000 / pfi->samplerate + pfi->padding;
    }

    if((pfi->frame_length > 2880) || (pfi->frame_length <= 0)) {
        pfi->is_valid=0;
        return -1;
    }

    pfi->is_valid=1;
    return 0;
}

/**
 * Scan 10 frames from the middle of the file and determine an
 * average bitrate from that.  It might not be as accurate as a full
 * frame count, but it's probably Close Enough (tm)
 *
 * @param infile file to scan for average bitrate
 * @param pfi pointer to frame info struct to put the bitrate into
 */
void scan_mp3_get_average_bitrate(FILE *infile, SCAN_FRAMEINFO *pfi) {
    off_t file_size;
    unsigned char frame_buffer[2900];
    unsigned char header[4];
    int index=0;
    int found=0;
    off_t pos;
    SCAN_FRAMEINFO fi;
    int frame_count=0;
    int bitrate_total=0;

    DPRINTF(E_DBG,L_SCAN,"Starting averaging bitrate\n");

    fseek(infile,0,SEEK_END);
    file_size=ftell(infile);

    pos=file_size/2;

    /* now, find the first frame */
    fseek(infile,pos,SEEK_SET);
    if(fread(frame_buffer,1,sizeof(frame_buffer),infile) != sizeof(frame_buffer))
        return;

    while(!found) {
        while((frame_buffer[index] != 0xFF) && (index < (sizeof(frame_buffer)-4)))
            index++;

        if(index >= (sizeof(frame_buffer)-4)) { /* largest mp3 frame is 2880 bytes */
            DPRINTF(E_DBG,L_SCAN,"Could not find frame... quitting\n");
            return;
        }

        if(!scan_mp3_decode_mp3_frame(&frame_buffer[index],&fi)) {
            /* see if next frame is valid */
            fseek(infile,pos + index + fi.frame_length,SEEK_SET);
            if(fread(header,1,sizeof(header),infile) != sizeof(header)) {
                DPRINTF(E_DBG,L_SCAN,"Could not read frame header\n");
                return;
            }

            if(!scan_mp3_decode_mp3_frame(header,&fi))
                found=1;
        }

        if(!found)
            index++;
    }

    pos += index;

    /* found first frame.  Let's move */
    while(frame_count < 10) {
        fseek(infile,pos,SEEK_SET);
        if(fread(header,1,sizeof(header),infile) != sizeof(header)) {
            DPRINTF(E_DBG,L_SCAN,"Could not read frame header\n");
            return;
        }
        if(scan_mp3_decode_mp3_frame(header,&fi)) {
            DPRINTF(E_DBG,L_SCAN,"Invalid frame header while averaging\n");
            return;
        }

        bitrate_total += fi.bitrate;
        frame_count++;
        pos += fi.frame_length;
    }

    DPRINTF(E_DBG,L_SCAN,"Old bitrate: %d\n",pfi->bitrate);
    pfi->bitrate = bitrate_total/frame_count;
    DPRINTF(E_DBG,L_SCAN,"New bitrate: %d\n",pfi->bitrate);

    return;
}

/**
 * do a full frame-by-frame scan of the file, counting frames
 * as we go to try and get a more accurate song length estimate.
 * If the song turns out to be CBR, then we'll not set the frame
 * length.  Instead we'll use the file size estimate, since it is
 * more consistent with iTunes.
 *
 * @param infile file to scan for frame count
 * @param pfi pointer to frame info struct to put framecount into
 */
void scan_mp3_get_frame_count(FILE *infile, SCAN_FRAMEINFO *pfi) {
    int pos;
    int frames=0;
    unsigned char frame_buffer[4];
    SCAN_FRAMEINFO fi;
    off_t file_size;
    int err=0;
    int cbr=1;
    int last_bitrate=0;

    DPRINTF(E_DBG,L_SCAN,"Starting frame count\n");

    fseek(infile,0,SEEK_END);
    file_size=ftell(infile);

    pos=pfi->frame_offset;

    while(1) {
        err=1;
        DPRINTF(E_SPAM,L_SCAN,"Seeking to %d\n",pos);

        fseek(infile,pos,SEEK_SET);
        if(fread(frame_buffer,1,sizeof(frame_buffer),infile) == sizeof(frame_buffer)) {
            /* check for valid frame */
            if(!scan_mp3_decode_mp3_frame(frame_buffer,&fi)) {
                frames++;
                pos += fi.frame_length;
                err=0;

                if((last_bitrate) && (fi.bitrate != last_bitrate))
                    cbr=0;
                last_bitrate=fi.bitrate;

                /* no point in brute scan of a cbr file... */
                if(cbr && (frames > 100)) {
                    DPRINTF(E_DBG,L_SCAN,"File appears to be CBR... quitting frame count\n");
                    return;
                }
            }
        }

        if(err) {
            if(pos > (file_size - 4096)) {  /* probably good enough */
                pfi->number_of_frames=frames;
                DPRINTF(E_DBG,L_SCAN,"Estimated frame count: %d\n",frames);
                return;
            } else {
                DPRINTF(E_DBG,L_SCAN,"Frame count aborted on error.  Pos=%d, Count=%d\n",
                        pos, frames);
                return;
            }
        }
    }
}


/**
 * Get information from the file headers itself -- like
 * song length, bit rate, etc.
 *
 * @param file File to get info for
 * @param pmp3 where to put the found information
 */
int scan_mp3_get_mp3fileinfo(char *file, MP3FILE *pmp3) {
    FILE *infile;
    SCAN_ID3HEADER *pid3;
    SCAN_FRAMEINFO fi;
    unsigned int size=0;
    off_t fp_size=0;
    off_t file_size;
    unsigned char buffer[1024];
    int index;

    int xing_flags;
    int found;

    int first_check=0;
    char frame_buffer[4];

    if(!(infile=fopen(file,"rb"))) {
        DPRINTF(E_WARN,L_SCAN,"Could not open %s for reading\n",file);
        return FALSE;
    }

    file_size = pmp3->file_size;

    memset((void*)&fi,0x00,sizeof(fi));

    if(fread(buffer,1,sizeof(buffer),infile) != sizeof(buffer)) {
        if(ferror(infile)) {
            DPRINTF(E_LOG,L_SCAN,"Error reading: %s\n",strerror(errno));
        } else {
            DPRINTF(E_LOG,L_SCAN,"Short file: %s\n",file);
        }
        fclose(infile);
        return FALSE;
    }

    pid3=(SCAN_ID3HEADER*)buffer;

    found=0;
    fp_size=0;

    if(strncmp((char*)pid3->id,"ID3",3)==0) {
        /* found an ID3 header... */
        DPRINTF(E_DBG,L_SCAN,"Found ID3 header\n");
        size = (pid3->size[0] << 21 | pid3->size[1] << 14 |
                pid3->size[2] << 7 | pid3->size[3]);
        fp_size=size + sizeof(SCAN_ID3HEADER);
        first_check=1;
        DPRINTF(E_DBG,L_SCAN,"Header length: %d\n",size);
    }

    index = 0;

    /* Here we start the brute-force header seeking.  Sure wish there
     * weren't so many crappy mp3 files out there
     */

    while(!found) {
        fseek(infile,fp_size,SEEK_SET);
        DPRINTF(E_DBG,L_SCAN,"Reading in new block at %d\n",(int)fp_size);
        if(fread(buffer,1,sizeof(buffer),infile) < sizeof(buffer)) {
            DPRINTF(E_LOG,L_SCAN,"Short read: %s\n",file);
            fclose(infile);
            return TRUE;
        }

        index=0;
        while(!found) {
            while((buffer[index] != 0xFF) && (index < (sizeof(buffer)-50)))
                index++;

            if((first_check) && (index)) {
                fp_size=0;
                DPRINTF(E_DBG,L_SCAN,"Bad header... dropping back for full frame search\n");
                first_check=0;
                break;
            }

            if(index > sizeof(buffer) - 50) {
                fp_size += index;
                DPRINTF(E_DBG,L_SCAN,"Block exhausted\n");
                break;
            }

            if(!scan_mp3_decode_mp3_frame(&buffer[index],&fi)) {
                DPRINTF(E_DBG,L_SCAN,"valid header at %d\n",index);
                if(strncasecmp((char*)&buffer[index+fi.xing_offset+4],"XING",4) == 0) {
                    /* no need to check further... if there is a xing header there,
                     * this is definately a valid frame */
                    found=1;
                    fp_size += index;
                } else {
                    /* No Xing... check for next frame */
                    DPRINTF(E_DBG,L_SCAN,"Found valid frame at %04x\n",(int)fp_size+index);
                    DPRINTF(E_DBG,L_SCAN,"Checking at %04x\n",(int)fp_size+index+fi.frame_length);
                    fseek(infile,fp_size + index + fi.frame_length,SEEK_SET);
                    if(fread(frame_buffer,1,sizeof(frame_buffer),infile) == sizeof(frame_buffer)) {
                        if(!scan_mp3_decode_mp3_frame((u_char*)frame_buffer,&fi)) {
                            found=1;
                            fp_size += index;
                        }
                    } else {
                        DPRINTF(E_LOG,L_SCAN,"Could not read frame header: %s\n",file);
                        fclose(infile);
                        return 0;
                    }

                    if(!found) {
                        DPRINTF(E_DBG,L_SCAN,"Didn't pan out.\n");
                    }
                }
            }

            if(!found) {
                index++;
                if (first_check) {
                    /* if the header info was wrong about where the data started,
                     * then start a brute-force scan from the beginning of the file.
                     * don't want to just scan forward, because we might have already
                     * missed the xing header
                     */
                    DPRINTF(E_DBG,L_SCAN,"Bad header... dropping back for full frame search\n");
                    first_check=0;
                    fp_size=0;
                    break;
                }
            }
        }
    }

    file_size -= fp_size;
    fi.frame_offset=fp_size;

    if(scan_mp3_decode_mp3_frame(&buffer[index],&fi)) {
        fclose(infile);
        DPRINTF(E_LOG,L_SCAN,"Could not find sync frame: %s\n",file);
        DPRINTF(E_LOG,L_SCAN,"If this is a valid mp3 file that plays in "
                "other applications, please email me at rpedde@users.sourceforge.net "
                "and tell me you got this error.  Thanks");
        return TRUE;
    }

    DPRINTF(E_DBG,L_SCAN," MPEG Version: %0.1g\n",fi.version);
    DPRINTF(E_DBG,L_SCAN," Layer: %d\n",fi.layer);
    DPRINTF(E_DBG,L_SCAN," Sample Rate: %d\n",fi.samplerate);
    DPRINTF(E_DBG,L_SCAN," Bit Rate: %d\n",fi.bitrate);

    /* now check for an XING header */
    if(strncasecmp((char*)&buffer[index+fi.xing_offset+4],"XING",4) == 0) {
        DPRINTF(E_DBG,L_SCAN,"Found Xing header\n");
        xing_flags = buffer[index+fi.xing_offset+4+4] << 24 |
           buffer[index+fi.xing_offset+4+5] << 16 |
           buffer[index+fi.xing_offset+4+6] << 8 |
           buffer[index+fi.xing_offset+4+7];

        DPRINTF(E_DBG,L_SCAN,"Xing Flags: %02X\n",xing_flags);

        if(xing_flags & 0x1) {
            /* Frames field is valid... */
            fi.number_of_frames=buffer[index+fi.xing_offset+4+8] << 24 |
                buffer[index+fi.xing_offset+4+9] << 16 |
                buffer[index+fi.xing_offset+4+10] << 8 |
                buffer[index+fi.xing_offset+4+11];
        }
        fi.bitrate = 0;
    }

    if((conf_get_int("general","scan_type",0) != 0) &&
       (fi.number_of_frames == 0) &&
       (!pmp3->song_length)) {
        /* We have no good estimate of song time, and we want more
         * aggressive scanning */
        DPRINTF(E_DBG,L_SCAN,"Starting aggressive file length scan\n");
        if(conf_get_int("general","scan_type",0) == 1) {
            /* get average bitrate */
            scan_mp3_get_average_bitrate(infile, &fi);
        } else {
            /* get full frame count */
            scan_mp3_get_frame_count(infile, &fi);
        }
    }

    pmp3->bitrate=fi.bitrate;
    pmp3->samplerate=fi.samplerate;

    /* guesstimate the file length */
    if(!pmp3->song_length) { /* could have gotten it from the tag */
        /* DWB: use ms time instead of seconds, use doubles to
           avoid overflow */
        if(!fi.number_of_frames) { /* not vbr */
            pmp3->song_length = (int) ((double) file_size * 8. /
                                       (double) fi.bitrate);

        } else if (fi.samplerate ) {
            pmp3->song_length = (int) ((double)(fi.number_of_frames*fi.samples_per_frame*1000.)/
                                       (double) fi.samplerate);
        }

        /* back-calculate bitrate from duration */
        if(pmp3->song_length) { /* could still be unknown */
            pmp3->bitrate = (file_size / pmp3->song_length) * 8;
        }

    }
    DPRINTF(E_DBG,L_SCAN," Song Length: %d\n",pmp3->song_length);

    fclose(infile);
    return TRUE;
}