id3 tag reading code, both v1 and v2. Still needs to be adjusted more to

remove the malloc()s and possible other stuff.


git-svn-id: svn://svn.rockbox.org/rockbox/trunk@185 a1c6a512-1295-4272-9138-f99709370657

1 files changed, 549 insertions, 0 deletions

diff --git a/firmware/id3.c b/firmware/id3.c
new file mode 100644
index 0000000000..825a54a718
--- /dev/null
+++ b/firmware/id3.c
@@ -0,0 +1,549 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   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 Härdeman.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <errno.h>
+
+struct mp3entry {
+    char *path;
+    char *title;
+    char *artist;
+    char *album;
+    int bitrate;
+    int frequency;
+    int id3v2len;
+    int id3v1len;
+    int filesize; /* in bytes */
+    int length;   /* song length */
+};
+
+typedef struct mp3entry mp3entry;
+
+typedef unsigned char bool;
+#define TRUE 1
+#define FALSE 0
+
+/* Some utility macros used in getsonglength() */
+#define CHECKSYNC(x) (((x >> 21) & 0x07FF) == 0x7FF)
+#define BYTE0(x) ((x >> 24) & 0xFF)
+#define BYTE1(x) ((x >> 16) & 0xFF)
+#define BYTE2(x) ((x >> 8)  & 0xFF)
+#define BYTE3(x) ((x >> 0)  & 0xFF)
+
+#define UNSYNC(b1,b2,b3,b4) (((b1 & 0x7F) << (3*7)) + \
+                             ((b2 & 0x7F) << (2*7)) + \
+                             ((b3 & 0x7F) << (1*7)) + \
+                             ((b4 & 0x7F) << (0*7)))
+
+#define HASID3V2(entry) entry->id3v2len > 0
+#define HASID3V1(entry) entry->id3v1len > 0
+
+/* Table of bitrates for MP3 files, all values in kilo.
+ * Indexed by version, layer and value of bit 15-12 in header.
+ */
+const int bitrate_table[2][3][16] =
+{
+    {
+        {0,32,64,96,128,160,192,224,256,288,320,352,384,416,448,0},
+        {0,32,48,56, 64,80, 96, 112,128,160,192,224,256,320,384,0},
+        {0,32,40,48, 56,64, 80, 96, 112,128,160,192,224,256,320,0}
+    },
+    {
+        {0,32,48,56,64,80,96,112,128,144,160,176,192,224,256,0},
+        {0, 8,16,24,32,40,48, 56, 64, 80, 96,112,128,144,160,0},
+        {0, 8,16,24,32,40,48, 56, 64, 80, 96,112,128,144,160,0}
+    }
+};
+
+/* Table of samples per frame for MP3 files.
+ * Indexed by layer. Multiplied with 1000.
+ */
+const int bs[4] = {0, 384000, 1152000, 1152000};
+
+/* Table of sample frequency for MP3 files.
+ * Indexed by version and layer.
+ */
+const int freqtab[2][4] =
+{
+    {44100, 48000, 32000, 0},
+    {22050, 24000, 16000, 0},
+};
+
+/*
+ * Removes trailing spaces from a string.
+ *
+ * Arguments: buffer - the string to process
+ *
+ * Returns: void
+ */
+static void 
+stripspaces(char *buffer) 
+{
+    int i = 0;
+    while(*(buffer + i) != '\0')
+        i++;
+	
+    for(;i >= 0; i--) {
+        if(*(buffer + i) == ' ')
+            *(buffer + i) = '\0';
+        else if(*(buffer + i) == '\0')
+            continue;
+        else
+            break;
+    }
+}
+
+/*
+ * 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(FILE *file, mp3entry *entry) 
+{
+    char buffer[31];
+    int offsets[3] = {-95,-65,-125};
+    int i;
+    char *result;
+
+    for(i=0;i<3;i++) {
+        if(fseek(file, offsets[i], SEEK_END) != 0) {
+            free(result);
+            return FALSE;
+        }
+
+        buffer[0]=0;
+        fgets(buffer, 31, file);
+        stripspaces(buffer);
+        
+        if(buffer[0]) {
+            switch(i) {
+            case 0:
+                entry->artist = strdup(buffer);
+                break;
+            case 1:
+                entry->album = strdup(buffer);
+                break;
+            case 2:
+                entry->title = strdup(buffer);
+                break;
+            }
+        }
+    }
+
+    return TRUE;
+}
+
+
+/*
+ * Sets the title of an MP3 entry based on its ID3v2 tag.
+ *
+ * Arguments: file - the MP3 file to scen 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(FILE *file, mp3entry *entry) 
+{
+    char *buffer;
+    int minframesize;
+    int size, readsize = 0, headerlen;
+    char *title = NULL;
+    char *artist = NULL;
+    char *album = NULL;
+    char header[10];
+    unsigned short int version;
+	
+    /* 10 = headerlength */
+    if(entry->id3v2len < 10)
+        return;
+
+    /* Check version */
+    fseek(file, 0, SEEK_SET);
+    fread(header, sizeof(char), 10, file);
+    version = (unsigned short int)header[3];
+	
+    /* Read all frames in the tag */
+    size = entry->id3v2len - 10;
+    buffer = malloc(size + 1);
+    if(size != (int)fread(buffer, sizeof(char), size, file)) {
+        free(buffer);
+        return;
+    }
+    *(buffer + size) = '\0';
+
+    /* Set minimun frame size according to ID3v2 version */
+    if(version > 2)
+        minframesize = 12;
+    else
+        minframesize = 8;
+
+    /* 
+     * We must have at least minframesize bytes left for the 
+     * remaining frames to be interesting 
+     */
+    while(size - readsize > minframesize) {
+        
+        /* Read frame header and check length */
+        if(version > 2) {
+            memcpy(header, (buffer + readsize), 10);
+            readsize += 10;
+            headerlen = UNSYNC(header[4], header[5], 
+                               header[6], header[7]);
+        } else {
+            memcpy(header, (buffer + readsize), 6);			
+            readsize += 6;
+            headerlen = (header[3] << 16) + 
+                (header[4] << 8) + 
+                (header[5]);
+        }
+        if(headerlen < 1)
+            continue;
+        
+        /* Check for certain frame headers */
+        if(!strncmp(header, "TPE1", strlen("TPE1")) || 
+           !strncmp(header, "TP1", strlen("TP1"))) {
+            readsize++;
+            headerlen--;
+            if(headerlen > (size - readsize))
+                headerlen = (size - readsize);
+            artist = malloc(headerlen + 1);
+            snprintf(artist, headerlen + 1, "%s", 
+                     (buffer + readsize));
+            readsize += headerlen;
+        }
+        else if(!strncmp(header, "TIT2", strlen("TIT2")) || 
+                !strncmp(header, "TT2", strlen("TT2"))) {
+            readsize++;
+            headerlen--;
+            if(headerlen > (size - readsize))
+                headerlen = (size - readsize);
+            title = malloc(headerlen + 1);
+            snprintf(title, headerlen + 1, "%s", 
+                     (buffer + readsize));
+            readsize += headerlen;
+        }
+        else if(!strncmp(header, "TALB", strlen("TALB"))) {
+            readsize++;
+            headerlen--;
+            if(headerlen > (size - readsize))
+                headerlen = (size - readsize);
+            album = malloc(headerlen + 1);
+            snprintf(album, headerlen + 1, "%s", 
+                     (buffer + readsize));
+            readsize += headerlen;
+        }
+    }
+    
+    if(artist)
+        entry->artist = artist;
+  
+    if(title)
+        entry->title = title;
+
+    if(album)
+        entry->album = album;
+  
+    free(buffer);
+}
+
+/*
+ * 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(FILE *file) 
+{
+    char buf[6];
+    int offset;
+	
+    /* Make sure file has a ID3 tag */
+    if((fseek(file, 0, SEEK_SET) != 0) ||
+       (fread(buf, sizeof(char), 6, file) != 6) ||
+       (strncmp(buf, "ID3", strlen("ID3")) != 0))
+        offset = 0;
+    /* Now check what the ID3v2 size field says */
+    else if(fread(buf, sizeof(char), 4, file) != 4)
+        offset = 0;
+    else
+        offset = UNSYNC(buf[0], buf[1], buf[2], buf[3]) + 10;
+	
+    return offset;
+}
+
+static int
+getfilesize(FILE *file)
+{
+    /* seek to the end of it */
+    if(fseek(file, 0, SEEK_END)) 
+        return 0; /* unknown */
+
+    return ftell(file);
+}
+
+/*
+ * Calculates the size of the ID3v1 tag.
+ *
+ * Arguments: file - the file to search for a tag.
+ *
+ * Returns: the size of the tag or 0 if none was found
+ */
+static int 
+getid3v1len(FILE *file) 
+{
+    char buf[3];
+    int offset;
+
+    /* Check if we find "TAG" 128 bytes from EOF */
+    if((fseek(file, -128, SEEK_END) != 0) ||
+       (fread(buf, sizeof(char), 3, file) != 3) ||
+       (strncmp(buf, "TAG", 3) != 0))
+        offset = 0;
+    else
+        offset = 128;
+	
+    return offset;
+}
+
+/*
+ * Calculates the length (in milliseconds) of an MP3 file. Currently this code
+ * doesn't care about VBR (Variable BitRate) files since it would have to scan
+ * through the entire file but this should become a config option in the
+ * future.
+ *
+ * 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, 
+ *          -1 means that it couldn't be calculated
+ */
+static int 
+getsonglength(FILE *file, mp3entry *entry)
+{
+    long header;
+    int version;
+    int layer;
+    int bitindex;
+    int bitrate;
+    int freqindex;
+    int frequency;
+
+    long bpf;
+    long tpf;
+    int i;
+
+    /* Start searching after ID3v2 header */ 
+    if(fseek(file, entry->id3v2len, SEEK_SET))
+        return -1;
+	
+    /* Fill up header with first 24 bits */
+    for(version = 0; version < 3; version++) {
+        header <<= 8;
+        if(!fread(&header, 1, 1, file))
+            return -1;
+    }
+	
+    /* Loop trough file until we find a frame header */
+ restart:
+    do {
+        header <<= 8;
+        if(!fread(&header, 1, 1, file))
+            return -1;
+    } while(!CHECKSYNC(header));
+	
+    /* 
+     * Some files are filled with garbage in the beginning, 
+     * if the bitrate index of the header is binary 1111 
+     * that is a good is a good indicator
+     */
+    if((header & 0xF000) == 0xF000)
+        goto restart;
+
+#ifdef DEBUG_STANDALONE
+    fprintf(stderr,
+            "We found %x-%x-%x-%x and checksync %i and test %x\n", 
+            BYTE0(header), BYTE1(header), BYTE2(header), BYTE3(header), 
+            CHECKSYNC(header), (header & 0xF000) == 0xF000);
+#endif
+    /* MPEG Audio Version */
+    switch((header & 0x180000) >> 19) {
+    case 2:
+        version = 2;
+        break;
+    case 3:
+        version = 1;
+        break;
+    default:
+        return -1;
+    }
+
+    /* Layer */
+    switch((header & 0x060000) >> 17) {
+    case 1:
+        layer = 3;
+        break;
+    case 2:
+        layer = 2;
+        break;
+    case 3:
+        layer = 1;
+        break;
+    default:
+        return -1;
+    }
+    
+    /* Bitrate */
+    bitindex = (header & 0xF000) >> 12;
+    bitrate = bitrate_table[version-1][layer-1][bitindex];
+    if(bitrate == 0)
+        return -1;
+
+    /* Sampling frequency */
+    freqindex = (header & 0x0C00) >> 10;
+    frequency = freqtab[version-1][freqindex];
+    if(frequency == 0)
+        return -1;
+
+#ifdef DEBUG_STANDALONE
+    fprintf(stderr,
+            "Version %i, lay %i, biti %i, bitr %i, freqi %i, freq %i\n", 
+            version, layer, bitindex, bitrate, freqindex, frequency);
+#endif
+    entry->bitrate = bitrate;
+    entry->frequency = frequency;
+	
+    /* Calculate bytes per frame, calculation depends on layer */
+    switch(layer) {
+    case 1:
+        bpf = bitrate_table[version - 1][layer - 1][bitindex];
+        bpf *= 12000.0 * 4.0;
+        bpf /= freqtab[version-1][freqindex] << (version - 1);
+        break;
+    case 2:
+    case 3:
+        bpf = bitrate_table[version - 1][layer - 1][bitindex];
+        bpf *= 144000;
+        bpf /= freqtab[version-1][freqindex] << (version - 1);
+        break;
+    default:
+        bpf = 1.0;
+    }
+	
+    /* Calculate time per frame */
+    tpf = bs[layer] / freqtab[version-1][freqindex] << (version - 1);
+
+    /* 
+     * Now song length is 
+     * ((filesize)/(bytes per frame))*(time per frame) 
+     */
+    return entry->filesize*tpf/bpf;
+}
+
+
+/*
+ * 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(mp3entry *entry, char *filename) 
+{
+    FILE *file;
+    char *copy;
+    char *title;
+
+    if((file = fopen(filename, "r")) == NULL)
+        return TRUE;
+
+    memset(entry, 0, sizeof(mp3entry));
+
+    entry->path = filename;
+
+    entry->filesize = getfilesize(file);
+    entry->id3v2len = getid3v2len(file);
+    entry->id3v1len = getid3v1len(file);
+    entry->length = getsonglength(file, entry);
+    entry->title = NULL;
+
+    if(HASID3V2(entry))
+        setid3v2title(file, entry);
+
+    if(HASID3V1(entry) && !entry->title)
+        setid3v1title(file, entry);
+	
+    fclose(file);
+
+    return FALSE;
+}
+
+#ifdef DEBUG_STANDALONE
+
+int main(int argc, char **argv)
+{
+    if(argc > 1) {
+        mp3entry mp3;
+        if(mp3info(&mp3, argv[1])) {
+            printf("Failed\n");
+            return 0;
+        }
+
+        printf("Title: %s\n"
+               "Artist: %s\n"
+               "Album:  %s\n"
+               "Length: %.1f secs\n"
+               "Bitrate: %d\n"
+               "Frequency: %d\n",
+               mp3.title?mp3.title:"<blank>",
+               mp3.artist?mp3.artist:"<blank>",
+               mp3.album?mp3.album:"<blank>",
+               mp3.length/1000.0,
+               mp3.bitrate,
+               mp3.frequency);
+    }
+    
+    return 0;
+}
+
+#endif
+
+/* -----------------------------------------------------------------
+ * local variables:
+ * eval: (load-file "rockbox-mode.el")
+ * end:
+ */