rockbox/firmware/id3.c

/***************************************************************************
 *             __________               __   ___.
 *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
 *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
 *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
 *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
 *                     \/            \/     \/    \/            \/
 * $Id$
 *
 * Copyright (C) 2002 by Daniel Stenberg
 *
 * All files in this archive are subject to the GNU General Public License.
 * See the file COPYING in the source tree root for full license agreement.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 ****************************************************************************/

/*
 * Parts of this code has been stolen from the Ample project and was written
 * by David H<EFBFBD>rdeman. It has since been extended and enhanced pretty much by
 * all sorts of friendly Rockbox people.
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <stdbool.h>
#include "file.h"
#include "debug.h"
#include "atoi.h"

#include "id3.h"
#include "mp3data.h"

#define UNSYNC(b0,b1,b2,b3) (((b0 & 0x7F) << (3*7)) | \
                             ((b1 & 0x7F) << (2*7)) | \
                             ((b2 & 0x7F) << (1*7)) | \
                             ((b3 & 0x7F) << (0*7)))

#define BYTES2INT(b0,b1,b2,b3) (((b0 & 0xFF) << (3*8)) | \
                                ((b1 & 0xFF) << (2*8)) | \
                                ((b2 & 0xFF) << (1*8)) | \
                                ((b3 & 0xFF) << (0*8)))

/* Checks to see if the passed in string is a 16-bit wide Unicode v2
   string.  If it is, we attempt to convert it to a 8-bit ASCII string
   (for valid 8-bit ASCII characters).  If it's not unicode, we leave
   it alone.  At some point we should fully support unicode strings */
static int unicode_munge(char** string, int *len) {
   int tmp;
   bool le = false;
   int i;
   char *str = *string;
   char *outstr = *string;

   if(str[0] > 0x03) {
      /* Plain old string */
      return 0;
   }
   
   /* Type 0x00 is ordinary ISO 8859-1 */
   if(str[0] == 0x00) {
      (*len)--;
      (*string)++; /* Skip the encoding type byte */
      return 0;
   }

   /* Unicode with or without BOM */
   if(str[0] == 0x01 || str[0] == 0x02) {
      str++;
      tmp = BYTES2INT(0, 0, str[0], str[1]);

      /* Now check if there is a BOM (zero-width non-breaking space, 0xfeff)
         and if it is in little or big endian format */
      if(tmp == 0xfffe) { /* Little endian? */
         le = true;
         str += 2;
      }

      if(tmp == 0xfeff) /* Big endian? */
         str += 2;

      i = 0;

      do {
         if(le) {
            if(str[1])
               outstr[i++] = '.';
            else
               outstr[i++] = str[0];
         } else {
            if(str[0])
               outstr[i++] = '.';
            else
               outstr[i++] = str[1];
         }
         str += 2;
      } while(str[0] || str[1]);

      *len = i;
      return 0;
   }

   /* If we come here, the string was of an unsupported type */
   *len = 1;
   outstr[0] = 0;
   return -1;
}

/*
 * Sets the title of an MP3 entry based on its ID3v1 tag.
 *
 * Arguments: file - the MP3 file to scen for a ID3v1 tag
 *            entry - the entry to set the title in
 *
 * Returns: true if a title was found and created, else false
 */
static bool setid3v1title(int fd, struct mp3entry *entry) 
{
    unsigned char buffer[128];
    static char offsets[] = {3, 33, 63, 93, 125, 127};
    int i, j;

    if (-1 == lseek(fd, -128, SEEK_END))
        return false;

    if (read(fd, buffer, sizeof buffer) != sizeof buffer)
        return false;

    if (strncmp(buffer, "TAG", 3))
        return false;

    entry->id3v1len = 128;
    entry->id3version = ID3_VER_1_0;

    for (i=0; i < (int)sizeof offsets; i++) {
        char* ptr = buffer + offsets[i];
        
        if (i<3) {
            /* kill trailing space in strings */
            for (j=29; j && ptr[j]==' '; j--)
                ptr[j] = 0;
        }

        switch(i) {
            case 0:
                strncpy(entry->id3v1buf[2], ptr, 30);
                entry->title = entry->id3v1buf[2];
                break;

            case 1:
                strncpy(entry->id3v1buf[0], ptr, 30);
                entry->artist = entry->id3v1buf[0];
                break;

            case 2:
                strncpy(entry->id3v1buf[1], ptr, 30);
                entry->album = entry->id3v1buf[1];
                break;

            case 3:
                ptr[4] = 0;
                entry->year = atoi(ptr);
                break;

            case 4:
                /* id3v1.1 uses last two bytes of comment field for track
                   number: first must be 0 and second is track num */
                if (!ptr[0] && ptr[1]) {
                    entry->tracknum = ptr[1];
                    entry->id3version = ID3_VER_1_1;
                }
                break;

            case 5:
                /* genre */
                entry->genre = ptr[0];
                break;
        }
    }

    return true;
}

static int read_frame(int fd, unsigned char *buf, char **destptr, int framelen)
{
    int bytesread;
    
    bytesread = read(fd, buf, framelen);
    if(bytesread < 0)
        return bytesread * 10 - 1;

    if(bytesread < framelen)
        return -1;
    
    *destptr = buf;
    if(unicode_munge(destptr, &bytesread) < 0)
        return -2;
    
    (*destptr)[bytesread] = '\0';
    return bytesread + 1;
}

/*
 * Sets the title of an MP3 entry based on its ID3v2 tag.
 *
 * Arguments: file - the MP3 file to scan for a ID3v2 tag
 *            entry - the entry to set the title in
 *
 * Returns: true if a title was found and created, else false
 */
static void setid3v2title(int fd, struct mp3entry *entry) 
{
    int minframesize;
    int size;
    int bufferpos = 0, totframelen, framelen;
    char header[10];
    unsigned char version;
    char *buffer = entry->id3v2buf;
    char *tmp = NULL;
    int bytesread = 0;
    int buffersize = sizeof(entry->id3v2buf);
    int flags;
    int skip;
	
    /* Bail out if the tag is shorter than 10 bytes */
    if(entry->id3v2len < 10)
        return;

    /* Read the ID3 tag version from the header */
    lseek(fd, 0, SEEK_SET);
    if(10 != read(fd, header, 10))
        return;

    /* Get the total ID3 tag size */
    size = entry->id3v2len - 10;

    version = header[3];
    switch ( version ) {
        case 2:
            version = ID3_VER_2_2;
            minframesize = 8;
            break;

        case 3:
            version = ID3_VER_2_3;
            minframesize = 12;
            break;

        case 4:
            version = ID3_VER_2_4;
            minframesize = 12;
            break;

        default:
            /* unsupported id3 version */
            return;
    }
    entry->id3version = version;
    entry->tracknum = entry->year = entry->genre = 0;
    entry->title = entry->artist = entry->album = NULL;
    
    /* Skip the extended header if it is present */
    if(version >= ID3_VER_2_4) {
        if(header[5] & 0x40) {
            if(4 != read(fd, header, 4))
                return;
            
            framelen = UNSYNC(header[0], header[1], 
                              header[2], header[3]);

            lseek(fd, framelen - 4, SEEK_CUR);
        }
    }
    
    /* 
     * We must have at least minframesize bytes left for the 
     * remaining frames to be interesting 
     */
    while(size > minframesize) {
        flags = 0;
        
        /* Read frame header and check length */
        if(version >= ID3_VER_2_3) {
            if(10 != read(fd, header, 10))
                return;
            /* Adjust for the 10 bytes we read */
            size -= 10;

            flags = BYTES2INT(0, 0, header[8], header[9]);
            
            if (version >= ID3_VER_2_4) {
                framelen = UNSYNC(header[4], header[5], 
                                  header[6], header[7]);
            } else {
                /* version .3 files don't use synchsafe ints for
                 * size */
                framelen = BYTES2INT(header[4], header[5], 
                                     header[6], header[7]);
            }
        } else {
            if(6 != read(fd, header, 6))
                return;
            /* Adjust for the 6 bytes we read */
            size -= 6;
            
            framelen = BYTES2INT(0, header[3], header[4], header[5]);
        }

        /* Keep track of the total size */
        totframelen = framelen;

        if(framelen == 0)
            return;

        if(flags)
        {
            skip = 0;
            
            if(flags & 0x0040) /* Grouping identity */
                skip++;

            if(flags & 0x000c) /* Compression or encryption */
            {
                /* Skip it using the total size in case
                   it was truncated */
                size -= totframelen;
                lseek(fd, totframelen, SEEK_CUR);
                continue;
            }

            /* The Unsynchronization flag can't be trusted, so we
               don't check it for now... */
            
            if(flags & 0x0001) /* Data length indicator */
                skip += 4;

            if(skip)
            {
                lseek(fd, skip, SEEK_CUR);
                framelen -= skip;
            }
        }
                
        /* If the frame is larger than the remaining buffer space we try
           to read as much as would fit in the buffer */
        if(framelen >= buffersize - bufferpos)
            framelen = buffersize - bufferpos - 1;

        DEBUGF("id3v2 frame: %.4s\n", header);

        /* Check for certain frame headers */
        if (!entry->artist &&
            (!strncmp(header, "TPE1", strlen("TPE1")) || 
             !strncmp(header, "TP1", strlen("TP1")))) {
            bytesread = read_frame(fd, buffer + bufferpos,
                                   &entry->artist, framelen);
            if(bytesread < 0)
                return;
            
            bufferpos += bytesread;
            size -= framelen;
        }
        else if (!entry->title &&
                 (!strncmp(header, "TIT2", strlen("TIT2")) || 
                  !strncmp(header, "TT2", strlen("TT2")))) {
            bytesread = read_frame(fd, buffer + bufferpos,
                                   &entry->title, framelen);
            if(bytesread < 0)
                return;
            
            bufferpos += bytesread;
            size -= framelen;
        }
        else if( !entry->album &&
                 !strncmp(header, "TALB", strlen("TALB"))) {
            bytesread = read_frame(fd, buffer + bufferpos,
                                   &entry->album, framelen);
            if(bytesread < 0)
                return;
            
            bufferpos += bytesread;
            size -= framelen;
        }
        else if (!entry->tracknum &&
                 !strncmp(header, "TRCK", strlen("TRCK"))) {
            bytesread = read_frame(fd, buffer + bufferpos,
                                   &tmp, framelen);
            if(bytesread < 0)
                return;
            
            entry->tracknum = atoi(tmp);

            size -= framelen;
        }
        else if (!entry->year &&
                 (!strncmp(header, "TYER", 4) ||
                  !strncmp(header, "TYR", 3))) {
            bytesread = read_frame(fd, buffer + bufferpos,
                                   &tmp, framelen);
            if(bytesread < 0)
                return;
            
            entry->year = atoi(tmp);
            size -= bytesread;
        }
        else if (!entry->genre &&
                 !strncmp(header, "TCON", 4)) {
            char* ptr = buffer + bufferpos;
            bytesread = read(fd, ptr, framelen);
            if(bytesread < 0 || bytesread < framelen)
                return;
            
            if (ptr[1] == '(' && ptr[2] != '(')
                entry->genre = atoi(ptr+2);
            bufferpos += bytesread + 1;
            size -= bytesread;
        }
        else {
            /* Unknown frame, skip it using the total size in case
               it was truncated */
            size -= totframelen;
            lseek(fd, totframelen, SEEK_CUR);
        }
    }
}

/*
 * Calculates the size of the ID3v2 tag.
 *
 * Arguments: file - the file to search for a tag.
 *
 * Returns: the size of the tag or 0 if none was found
 */
static int getid3v2len(int fd) 
{
    char buf[6];
    int offset;
	
    /* Make sure file has a ID3 tag */
    if((-1 == lseek(fd, 0, SEEK_SET)) ||
       (read(fd, buf, 6) != 6) ||
       (strncmp(buf, "ID3", strlen("ID3")) != 0))
        offset = 0;

    /* Now check what the ID3v2 size field says */
    else if(read(fd, buf, 4) != 4)
        offset = 0;
    else
        offset = UNSYNC(buf[0], buf[1], buf[2], buf[3]) + 10;

    DEBUGF("ID3V2 Length: 0x%x\n", offset);
    return offset;
}

/*
 * Calculates the length (in milliseconds) of an MP3 file.
 *
 * Modified to only use integers.
 *
 * Arguments: file - the file to calculate the length upon
 *            entry - the entry to update with the length
 *
 * Returns: the song length in milliseconds, 
 *          0 means that it couldn't be calculated
 */
static int getsonglength(int fd, struct mp3entry *entry)
{
    unsigned int filetime = 0;
    struct mp3info info;
    int bytecount;
    
    /* Start searching after ID3v2 header */ 
    if(-1 == lseek(fd, entry->id3v2len, SEEK_SET))
        return 0;

    bytecount = get_mp3file_info(fd, &info);

    DEBUGF("Space between ID3V2 tag and first audio frame: 0x%x bytes\n",
           bytecount);

    if(bytecount < 0)
        return -1;
    
    bytecount += entry->id3v2len;

    entry->bitrate = info.bitrate;
    entry->frequency = info.frequency;
    entry->version = info.version;
    entry->layer = info.layer;

    /* If the file time hasn't been established, this may be a fixed
       rate MP3, so just use the default formula */

    filetime = info.file_time;
    
    if(filetime == 0)
    {
        /* 
         * Now song length is 
         * ((filesize)/(bytes per frame))*(time per frame) 
         */
        filetime = entry->filesize/info.frame_size*info.frame_time;
    }

    entry->tpf = info.frame_time;
    entry->bpf = info.frame_size;
    
    entry->vbr = info.is_vbr;
    entry->has_toc = info.has_toc;
    memcpy(entry->toc, info.toc, sizeof(info.toc));

    entry->vbr_header_pos = info.vbr_header_pos;
    
    /* Update the seek point for the first playable frame */
    entry->first_frame_offset = bytecount;
    DEBUGF("First frame is at %x\n", entry->first_frame_offset);

    return filetime;
}

/*
 * Checks all relevant information (such as ID3v1 tag, ID3v2 tag, length etc)
 * about an MP3 file and updates it's entry accordingly.
 *
 * Arguments: entry - the entry to check and update with the new information
 *
 * Returns: void
 */
bool mp3info(struct mp3entry *entry, char *filename) 
{
    int fd;
    fd = open(filename, O_RDONLY);
    if(-1 == fd)
        return true;

    memset(entry, 0, sizeof(struct mp3entry));
   
    strncpy(entry->path, filename, sizeof(entry->path));
 
    entry->title = NULL;
    entry->filesize = filesize(fd);
    entry->id3v2len = getid3v2len(fd);
    entry->tracknum = 0;
    entry->genre = 0xff;

    if (entry->id3v2len)
        setid3v2title(fd, entry);
    entry->length = getsonglength(fd, entry);

    /* Subtract the meta information from the file size to get
       the true size of the MP3 stream */
    entry->filesize -= entry->first_frame_offset;
    
    /* only seek to end of file if no id3v2 tags were found */
    if (!entry->id3v2len) {
        if(!entry->title)
            setid3v1title(fd, entry);
    }

    close(fd);

    if(!entry->length || (entry->filesize < 8 ))
        /* no song length or less than 8 bytes is hereby considered to be an
           invalid mp3 and won't be played by us! */
        return true;

    return false;
}

#ifdef DEBUG_STANDALONE

char *secs2str(int ms)
{
    static char buffer[32];
    int secs = ms/1000;
    ms %= 1000;
    snprintf(buffer, sizeof(buffer), "%d:%02d.%d", secs/60, secs%60, ms/100);
    return buffer;
}

int main(int argc, char **argv)
{
    int i;
    for(i=1; i<argc; i++) {
        struct mp3entry mp3;
        if(mp3info(&mp3, argv[i])) {
            printf("Failed to get %s\n", argv[i]);
            return 0;
        }

        printf("****** File: %s\n"
               "      Title: %s\n"
               "     Artist: %s\n"
               "      Album: %s\n"
               "     Length: %s / %d s\n"
               "    Bitrate: %d\n"
               "  Frequency: %d\n",
               argv[i],
               mp3.title?mp3.title:"<blank>",
               mp3.artist?mp3.artist:"<blank>",
               mp3.album?mp3.album:"<blank>",
               secs2str(mp3.length),
               mp3.length/1000,
               mp3.bitrate,
               mp3.frequency);
    }
    
    return 0;
}

#endif