/*
  * Copyright (c) 2003 Fabrice Bellard
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * FFmpeg 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
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 

 /**
  * @file
  * ID3v2 header parser
  *
  * Specifications available at:
  * http://id3.org/Developer_Information
  */
 

 #include "config.h"
 
 #if CONFIG_ZLIB
 #include <zlib.h>
 #endif
 

 #include "id3v2.h"

 #include "id3v1.h"
 #include "libavutil/avstring.h"

 #include "libavutil/intreadwrite.h"

 #include "libavutil/dict.h"

 #include "avio_internal.h"

 #include "internal.h"

 const AVMetadataConv ff_id3v2_34_metadata_conv[] = {
     { "TALB", "album"},
     { "TCOM", "composer"},
     { "TCON", "genre"},
     { "TCOP", "copyright"},
     { "TENC", "encoded_by"},
     { "TIT2", "title"},
     { "TLAN", "language"},
     { "TPE1", "artist"},
     { "TPE2", "album_artist"},
     { "TPE3", "performer"},
     { "TPOS", "disc"},
     { "TPUB", "publisher"},
     { "TRCK", "track"},
     { "TSSE", "encoder"},
     { 0 }
 };
 
 const AVMetadataConv ff_id3v2_4_metadata_conv[] = {
     { "TDRL", "date"},
     { "TDRC", "date"},
     { "TDEN", "creation_time"},
     { "TSOA", "album-sort"},
     { "TSOP", "artist-sort"},
     { "TSOT", "title-sort"},
     { 0 }
 };
 

 static const AVMetadataConv id3v2_2_metadata_conv[] = {

     { "TAL",  "album"},
     { "TCO",  "genre"},
     { "TT2",  "title"},
     { "TEN",  "encoded_by"},
     { "TP1",  "artist"},
     { "TP2",  "album_artist"},
     { "TP3",  "performer"},
     { "TRK",  "track"},
     { 0 }
 };
 
 
 const char ff_id3v2_tags[][4] = {
    "TALB", "TBPM", "TCOM", "TCON", "TCOP", "TDLY", "TENC", "TEXT",
    "TFLT", "TIT1", "TIT2", "TIT3", "TKEY", "TLAN", "TLEN", "TMED",
    "TOAL", "TOFN", "TOLY", "TOPE", "TOWN", "TPE1", "TPE2", "TPE3",
    "TPE4", "TPOS", "TPUB", "TRCK", "TRSN", "TRSO", "TSRC", "TSSE",
    { 0 },
 };
 
 const char ff_id3v2_4_tags[][4] = {
    "TDEN", "TDOR", "TDRC", "TDRL", "TDTG", "TIPL", "TMCL", "TMOO",
    "TPRO", "TSOA", "TSOP", "TSOT", "TSST",
    { 0 },
 };
 
 const char ff_id3v2_3_tags[][4] = {
    "TDAT", "TIME", "TORY", "TRDA", "TSIZ", "TYER",
    { 0 },
 };
 

 const char *ff_id3v2_picture_types[21] = {
     "Other",
     "32x32 pixels 'file icon'",
     "Other file icon",
     "Cover (front)",
     "Cover (back)",
     "Leaflet page",
     "Media (e.g. label side of CD)",
     "Lead artist/lead performer/soloist",
     "Artist/performer",
     "Conductor",
     "Band/Orchestra",
     "Composer",
     "Lyricist/text writer",
     "Recording Location",
     "During recording",
     "During performance",
     "Movie/video screen capture",
     "A bright coloured fish",
     "Illustration",
     "Band/artist logotype",
     "Publisher/Studio logotype",
 };
 
 const CodecMime ff_id3v2_mime_tags[] = {

     {"image/gif" , AV_CODEC_ID_GIF},
     {"image/jpeg", AV_CODEC_ID_MJPEG},
     {"image/jpg",  AV_CODEC_ID_MJPEG},
     {"image/png" , AV_CODEC_ID_PNG},
     {"image/tiff", AV_CODEC_ID_TIFF},
     {"image/bmp",  AV_CODEC_ID_BMP},

     {"JPG",        AV_CODEC_ID_MJPEG}, /* ID3v2.2  */
     {"PNG" ,       AV_CODEC_ID_PNG},   /* ID3v2.2  */

     {"",           AV_CODEC_ID_NONE},

 };
 

 int ff_id3v2_match(const uint8_t *buf, const char * magic)

 {

     return  buf[0]         == magic[0] &&
             buf[1]         == magic[1] &&
             buf[2]         == magic[2] &&

             buf[3]         != 0xff &&
             buf[4]         != 0xff &&
            (buf[6] & 0x80) ==    0 &&
            (buf[7] & 0x80) ==    0 &&
            (buf[8] & 0x80) ==    0 &&

            (buf[9] & 0x80) ==    0;

 }

 
 int ff_id3v2_tag_len(const uint8_t * buf)
 {
     int len = ((buf[6] & 0x7f) << 21) +

               ((buf[7] & 0x7f) << 14) +
               ((buf[8] & 0x7f) << 7) +
                (buf[9] & 0x7f) +
               ID3v2_HEADER_SIZE;

     if (buf[5] & 0x10)
         len += ID3v2_HEADER_SIZE;
     return len;
 }

 static unsigned int get_size(AVIOContext *s, int len)

 {

     int v = 0;
     while (len--)

         v = (v << 7) + (avio_r8(s) & 0x7F);

     return v;
 }
 

 /**
  * Free GEOB type extra metadata.
  */

 static void free_geobtag(void *obj)

 {

     ID3v2ExtraMetaGEOB *geob = obj;

     av_free(geob->mime_type);
     av_free(geob->file_name);
     av_free(geob->description);
     av_free(geob->data);
     av_free(geob);
 }

 /**
  * Decode characters to UTF-8 according to encoding type. The decoded buffer is

  * always null terminated. Stop reading when either *maxread bytes are read from
  * pb or U+0000 character is found.

  *
  * @param dst Pointer where the address of the buffer with the decoded bytes is
  * stored. Buffer must be freed by caller.
  * @param maxread Pointer to maximum number of characters to read from the
  * AVIOContext. After execution the value is decremented by the number of bytes
  * actually read.

  * @returns 0 if no error occurred, dst is uninitialized on error

  */
 static int decode_str(AVFormatContext *s, AVIOContext *pb, int encoding,

                       uint8_t **dst, int *maxread)

 {

     int ret;

     uint8_t tmp;
     uint32_t ch = 1;
     int left = *maxread;
     unsigned int (*get)(AVIOContext*) = avio_rb16;
     AVIOContext *dynbuf;

     if ((ret = avio_open_dyn_buf(&dynbuf)) < 0) {
         av_log(s, AV_LOG_ERROR, "Error opening memory stream\n");
         return ret;
     }

     switch (encoding) {

     case ID3v2_ENCODING_ISO8859:

         while (left && ch) {

             ch = avio_r8(pb);
             PUT_UTF8(ch, tmp, avio_w8(dynbuf, tmp);)
             left--;

         }
         break;
 

     case ID3v2_ENCODING_UTF16BOM:

         if ((left -= 2) < 0) {
             av_log(s, AV_LOG_ERROR, "Cannot read BOM value, input too short\n");

             avio_close_dyn_buf(dynbuf, dst);

             av_freep(dst);
             return AVERROR_INVALIDDATA;
         }

         switch (avio_rb16(pb)) {

         case 0xfffe:

             get = avio_rl16;

         case 0xfeff:
             break;
         default:

             av_log(s, AV_LOG_ERROR, "Incorrect BOM value\n");

             avio_close_dyn_buf(dynbuf, dst);

             av_freep(dst);
             *maxread = left;
             return AVERROR_INVALIDDATA;

         }
         // fall-through
 

     case ID3v2_ENCODING_UTF16BE:

         while ((left > 1) && ch) {

             GET_UTF16(ch, ((left -= 2) >= 0 ? get(pb) : 0), break;)
             PUT_UTF8(ch, tmp, avio_w8(dynbuf, tmp);)

         }

         if (left < 0)
             left += 2; /* did not read last char from pb */

         break;
 

     case ID3v2_ENCODING_UTF8:

         while (left && ch) {

             ch = avio_r8(pb);
             avio_w8(dynbuf, ch);
             left--;
         }

         break;

     default:

         av_log(s, AV_LOG_WARNING, "Unknown encoding\n");
     }
 
     if (ch)
         avio_w8(dynbuf, 0);
 

     avio_close_dyn_buf(dynbuf, dst);

     *maxread = left;
 
     return 0;
 }
 
 /**
  * Parse a text tag.
  */
 static void read_ttag(AVFormatContext *s, AVIOContext *pb, int taglen, const char *key)
 {
     uint8_t *dst;

     int encoding, dict_flags = AV_DICT_DONT_OVERWRITE | AV_DICT_DONT_STRDUP_VAL;

     unsigned genre;
 
     if (taglen < 1)
         return;
 

     encoding = avio_r8(pb);

     taglen--; /* account for encoding type byte */
 

     if (decode_str(s, pb, encoding, &dst, &taglen) < 0) {

         av_log(s, AV_LOG_ERROR, "Error reading frame %s, skipped\n", key);
         return;

     }
 

     if (!(strcmp(key, "TCON") && strcmp(key, "TCO"))

         && (sscanf(dst, "(%d)", &genre) == 1 || sscanf(dst, "%d", &genre) == 1)

         && genre <= ID3v1_GENRE_MAX) {
         av_freep(&dst);

         dst = av_strdup(ff_id3v1_genre_str[genre]);

     } else if (!(strcmp(key, "TXXX") && strcmp(key, "TXX"))) {
         /* dst now contains the key, need to get value */

         key = dst;

         if (decode_str(s, pb, encoding, &dst, &taglen) < 0) {
             av_log(s, AV_LOG_ERROR, "Error reading frame %s, skipped\n", key);
             av_freep(&key);
             return;
         }

         dict_flags |= AV_DICT_DONT_STRDUP_KEY;
     } else if (!*dst)

         av_freep(&dst);

     if (dst)
         av_dict_set(&s->metadata, key, dst, dict_flags);

 }
 
 /**
  * Parse GEOB tag into a ID3v2ExtraMetaGEOB struct.
  */
 static void read_geobtag(AVFormatContext *s, AVIOContext *pb, int taglen, char *tag, ID3v2ExtraMeta **extra_meta)
 {
     ID3v2ExtraMetaGEOB *geob_data = NULL;
     ID3v2ExtraMeta *new_extra = NULL;
     char encoding;
     unsigned int len;
 
     if (taglen < 1)
         return;
 
     geob_data = av_mallocz(sizeof(ID3v2ExtraMetaGEOB));
     if (!geob_data) {
         av_log(s, AV_LOG_ERROR, "Failed to alloc %zu bytes\n", sizeof(ID3v2ExtraMetaGEOB));
         return;
     }
 
     new_extra = av_mallocz(sizeof(ID3v2ExtraMeta));
     if (!new_extra) {
         av_log(s, AV_LOG_ERROR, "Failed to alloc %zu bytes\n", sizeof(ID3v2ExtraMeta));
         goto fail;
     }
 
     /* read encoding type byte */
     encoding = avio_r8(pb);
     taglen--;
 
     /* read MIME type (always ISO-8859) */

     if (decode_str(s, pb, ID3v2_ENCODING_ISO8859, &geob_data->mime_type, &taglen) < 0

         || taglen <= 0)
         goto fail;
 
     /* read file name */

     if (decode_str(s, pb, encoding, &geob_data->file_name, &taglen) < 0

         || taglen <= 0)
         goto fail;
 
     /* read content description */

     if (decode_str(s, pb, encoding, &geob_data->description, &taglen) < 0

         || taglen < 0)
         goto fail;
 
     if (taglen) {
         /* save encapsulated binary data */
         geob_data->data = av_malloc(taglen);
         if (!geob_data->data) {
             av_log(s, AV_LOG_ERROR, "Failed to alloc %d bytes\n", taglen);
             goto fail;
         }
         if ((len = avio_read(pb, geob_data->data, taglen)) < taglen)
             av_log(s, AV_LOG_WARNING, "Error reading GEOB frame, data truncated.\n");
         geob_data->datasize = len;
     } else {
         geob_data->data = NULL;
         geob_data->datasize = 0;
     }
 
     /* add data to the list */
     new_extra->tag = "GEOB";
     new_extra->data = geob_data;
     new_extra->next = *extra_meta;
     *extra_meta = new_extra;
 
     return;
 
 fail:
     av_log(s, AV_LOG_ERROR, "Error reading frame %s, skipped\n", tag);
     free_geobtag(geob_data);
     av_free(new_extra);
     return;

 }
 

 static int is_number(const char *str)
 {
     while (*str >= '0' && *str <= '9') str++;
     return !*str;
 }
 

 static AVDictionaryEntry* get_date_tag(AVDictionary *m, const char *tag)

 {

     AVDictionaryEntry *t;
     if ((t = av_dict_get(m, tag, NULL, AV_DICT_MATCH_CASE)) &&

         strlen(t->value) == 4 && is_number(t->value))
         return t;
     return NULL;
 }
 

 static void merge_date(AVDictionary **m)

 {

     AVDictionaryEntry *t;

     char date[17] = {0};      // YYYY-MM-DD hh:mm
 
     if (!(t = get_date_tag(*m, "TYER")) &&
         !(t = get_date_tag(*m, "TYE")))
         return;
     av_strlcpy(date, t->value, 5);

     av_dict_set(m, "TYER", NULL, 0);
     av_dict_set(m, "TYE",  NULL, 0);

 
     if (!(t = get_date_tag(*m, "TDAT")) &&
         !(t = get_date_tag(*m, "TDA")))
         goto finish;
     snprintf(date + 4, sizeof(date) - 4, "-%.2s-%.2s", t->value + 2, t->value);

     av_dict_set(m, "TDAT", NULL, 0);
     av_dict_set(m, "TDA",  NULL, 0);

 
     if (!(t = get_date_tag(*m, "TIME")) &&
         !(t = get_date_tag(*m, "TIM")))
         goto finish;
     snprintf(date + 10, sizeof(date) - 10, " %.2s:%.2s", t->value, t->value + 2);

     av_dict_set(m, "TIME", NULL, 0);
     av_dict_set(m, "TIM",  NULL, 0);

 
 finish:
     if (date[0])

         av_dict_set(m, "date", date, 0);

 }
 

 static void free_apic(void *obj)
 {
     ID3v2ExtraMetaAPIC *apic = obj;
     av_freep(&apic->data);
     av_freep(&apic->description);
     av_freep(&apic);
 }
 
 static void read_apic(AVFormatContext *s, AVIOContext *pb, int taglen, char *tag, ID3v2ExtraMeta **extra_meta)
 {
     int enc, pic_type;
     char             mimetype[64];
     const CodecMime     *mime = ff_id3v2_mime_tags;

     enum AVCodecID           id = AV_CODEC_ID_NONE;

     ID3v2ExtraMetaAPIC  *apic = NULL;
     ID3v2ExtraMeta *new_extra = NULL;
     int64_t               end = avio_tell(pb) + taglen;
 
     if (taglen <= 4)
         goto fail;
 
     new_extra = av_mallocz(sizeof(*new_extra));
     apic      = av_mallocz(sizeof(*apic));
     if (!new_extra || !apic)
         goto fail;
 
     enc = avio_r8(pb);
     taglen--;
 
     /* mimetype */
     taglen -= avio_get_str(pb, taglen, mimetype, sizeof(mimetype));

     while (mime->id != AV_CODEC_ID_NONE) {

         if (!av_strncasecmp(mime->str, mimetype, sizeof(mimetype))) {

             id = mime->id;
             break;
         }
         mime++;
     }

     if (id == AV_CODEC_ID_NONE) {

         av_log(s, AV_LOG_WARNING, "Unknown attached picture mimetype: %s, skipping.\n", mimetype);
         goto fail;
     }
     apic->id = id;
 
     /* picture type */
     pic_type = avio_r8(pb);
     taglen--;
     if (pic_type < 0 || pic_type >= FF_ARRAY_ELEMS(ff_id3v2_picture_types)) {
         av_log(s, AV_LOG_WARNING, "Unknown attached picture type %d.\n", pic_type);
         pic_type = 0;
     }
     apic->type = ff_id3v2_picture_types[pic_type];
 
     /* description and picture data */
     if (decode_str(s, pb, enc, &apic->description, &taglen) < 0) {
         av_log(s, AV_LOG_ERROR, "Error decoding attached picture description.\n");
         goto fail;
     }
 
     apic->len   = taglen;

     apic->data  = av_malloc(taglen + FF_INPUT_BUFFER_PADDING_SIZE);

     if (!apic->data || !apic->len || avio_read(pb, apic->data, taglen) != taglen)

         goto fail;

     memset(apic->data + taglen, 0, FF_INPUT_BUFFER_PADDING_SIZE);

 
     new_extra->tag    = "APIC";
     new_extra->data   = apic;
     new_extra->next   = *extra_meta;
     *extra_meta       = new_extra;
 
     return;
 
 fail:
     if (apic)
         free_apic(apic);
     av_freep(&new_extra);
     avio_seek(pb, end, SEEK_SET);
 }
 

 static void read_chapter(AVFormatContext *s, AVIOContext *pb, int taglen, char *tag, ID3v2ExtraMeta **extra_meta)
 {
     AVRational time_base = {1, 1000};
     char title[1024];
     uint32_t start, end;
 
     taglen -= avio_get_str(pb, taglen, title, sizeof(title));
     if (taglen < 16)
         return;
 
     start = avio_rb32(pb);
     end   = avio_rb32(pb);
     taglen -= 27;
     if (taglen > 0) {
         char tag[4];
 
         avio_skip(pb, 8);
         avio_read(pb, tag, 4);
         if (!memcmp(tag, "TIT2", 4)) {
             taglen = FFMIN(taglen, avio_rb32(pb));
             if (taglen < 0)
                 return;
             avio_skip(pb, 3);
             avio_get_str(pb, taglen, title, sizeof(title));
         }
     }
 
     avpriv_new_chapter(s, s->nb_chapters + 1, time_base, start, end, title);
 }
 

 typedef struct ID3v2EMFunc {
     const char *tag3;
     const char *tag4;
     void (*read)(AVFormatContext*, AVIOContext*, int, char*, ID3v2ExtraMeta **);

     void (*free)(void *obj);

 } ID3v2EMFunc;
 
 static const ID3v2EMFunc id3v2_extra_meta_funcs[] = {

     { "GEO", "GEOB", read_geobtag, free_geobtag },

     { "PIC", "APIC", read_apic,    free_apic },

     { "CHAP","CHAP", read_chapter, NULL },

     { NULL }
 };
 

 /**
  * Get the corresponding ID3v2EMFunc struct for a tag.
  * @param isv34 Determines if v2.2 or v2.3/4 strings are used
  * @return A pointer to the ID3v2EMFunc struct if found, NULL otherwise.
  */
 static const ID3v2EMFunc *get_extra_meta_func(const char *tag, int isv34)
 {
     int i = 0;

     while (id3v2_extra_meta_funcs[i].tag3) {

         if (tag && !memcmp(tag,

                     (isv34 ? id3v2_extra_meta_funcs[i].tag4 :
                              id3v2_extra_meta_funcs[i].tag3),

                     (isv34 ? 4 : 3)))

             return &id3v2_extra_meta_funcs[i];

         i++;
     }

     return NULL;

 }
 
 static void ff_id3v2_parse(AVFormatContext *s, int len, uint8_t version, uint8_t flags, ID3v2ExtraMeta **extra_meta)

 {

     int isv34, unsync;
     unsigned tlen;

     char tag[5];

     int64_t next, end = avio_tell(s->pb) + len;

     int taghdrlen;

     const char *reason = NULL;

     AVIOContext pb;

     AVIOContext *pbx;

     unsigned char *buffer = NULL;
     int buffer_size = 0;

     const ID3v2EMFunc *extra_func = NULL;

     unsigned char *uncompressed_buffer = NULL;
     int uncompressed_buffer_size = 0;

     av_log(s, AV_LOG_DEBUG, "id3v2 ver:%d flags:%02X len:%d\n", version, flags, len);
 

     switch (version) {

     case 2:

         if (flags & 0x40) {

             reason = "compression";
             goto error;
         }
         isv34 = 0;
         taghdrlen = 6;
         break;
 
     case 3:
     case 4:
         isv34 = 1;
         taghdrlen = 10;
         break;
 
     default:
         reason = "version";
         goto error;
     }
 

     unsync = flags & 0x80;

     if (isv34 && flags & 0x40) { /* Extended header present, just skip over it */
         int extlen = get_size(s->pb, 4);
         if (version == 4)
             extlen -= 4;     // in v2.4 the length includes the length field we just read
 
         if (extlen < 0) {
             reason = "invalid extended header length";

             goto error;
         }

         avio_skip(s->pb, extlen);

         len -= extlen + 4;

         if (len < 0) {
             reason = "extended header too long.";
             goto error;
         }
     }

     while (len >= taghdrlen) {

         unsigned int tflags = 0;

         int tunsync = 0;

         int tcomp = 0;
         int tencr = 0;

         unsigned long dlen;

         if (isv34) {

             avio_read(s->pb, tag, 4);

             tag[4] = 0;

             if(version==3){

                 tlen = avio_rb32(s->pb);

             }else
                 tlen = get_size(s->pb, 4);

             tflags = avio_rb16(s->pb);

             tunsync = tflags & ID3v2_FLAG_UNSYNCH;

         } else {

             avio_read(s->pb, tag, 3);

             tag[3] = 0;

             tlen = avio_rb24(s->pb);

         }

         if (tlen > (1<<28))

             break;

         len -= taghdrlen + tlen;
 

         if (len < 0)

             break;
 

         next = avio_tell(s->pb) + tlen;

         if (!tlen) {
             if (tag[0])
                 av_log(s, AV_LOG_DEBUG, "Invalid empty frame %s, skipping.\n", tag);
             continue;
         }
 

         if (tflags & ID3v2_FLAG_DATALEN) {

             if (tlen < 4)
                 break;

             dlen = avio_rb32(s->pb);

             tlen -= 4;

         } else
             dlen = tlen;
 
         tcomp = tflags & ID3v2_FLAG_COMPRESSION;
         tencr = tflags & ID3v2_FLAG_ENCRYPTION;
 
         /* skip encrypted tags and, if no zlib, compressed tags */
         if (tencr || (!CONFIG_ZLIB && tcomp)) {
             const char *type;
             if (!tcomp)
                 type = "encrypted";
             else if (!tencr)
                 type = "compressed";
             else
                 type = "encrypted and compressed";

             av_log(s, AV_LOG_WARNING, "Skipping %s ID3v2 frame %s.\n", type, tag);

             avio_skip(s->pb, tlen);

         /* check for text tag or supported special meta tag */

         } else if (tag[0] == 'T' || (extra_meta && (extra_func = get_extra_meta_func(tag, isv34)))) {

             pbx = s->pb;

             if (unsync || tunsync || tcomp) {
                 av_fast_malloc(&buffer, &buffer_size, tlen);

                 if (!buffer) {

                     av_log(s, AV_LOG_ERROR, "Failed to alloc %d bytes\n", tlen);

                     goto seek;
                 }

             }
             if (unsync || tunsync) {
                 int64_t end = avio_tell(s->pb) + tlen;
                 uint8_t *b;
 

                 b = buffer;

                 while (avio_tell(s->pb) < end && b - buffer < tlen && !s->pb->eof_reached) {

                     *b++ = avio_r8(s->pb);

                     if (*(b - 1) == 0xff && avio_tell(s->pb) < end - 1 &&

                         b - buffer < tlen &&

                         !s->pb->eof_reached ) {

                         uint8_t val = avio_r8(s->pb);
                         *b++ = val ? val : avio_r8(s->pb);
                     }
                 }
                 ffio_init_context(&pb, buffer, b - buffer, 0, NULL, NULL, NULL, NULL);
                 tlen = b - buffer;
                 pbx = &pb; // read from sync buffer
             }
 

 #if CONFIG_ZLIB
                 if (tcomp) {

                     int err;

                     av_log(s, AV_LOG_DEBUG, "Compresssed frame %s tlen=%d dlen=%ld\n", tag, tlen, dlen);

                     av_fast_malloc(&uncompressed_buffer, &uncompressed_buffer_size, dlen);
                     if (!uncompressed_buffer) {
                         av_log(s, AV_LOG_ERROR, "Failed to alloc %ld bytes\n", dlen);

                         goto seek;
                     }
 

                     if (!(unsync || tunsync)) {
                         err = avio_read(s->pb, buffer, tlen);
                         if (err < 0) {
                             av_log(s, AV_LOG_ERROR, "Failed to read compressed tag\n");
                             goto seek;
                         }
                         tlen = err;

                     }
 

                     err = uncompress(uncompressed_buffer, &dlen, buffer, tlen);

                     if (err != Z_OK) {
                         av_log(s, AV_LOG_ERROR, "Failed to uncompress tag: %d\n", err);
                         goto seek;
                     }

                     ffio_init_context(&pb, uncompressed_buffer, dlen, 0, NULL, NULL, NULL, NULL);
                     tlen = dlen;
                     pbx = &pb; // read from sync buffer

                 }
 #endif

             if (tag[0] == 'T')
                 /* parse text tag */
                 read_ttag(s, pbx, tlen, tag);
             else
                 /* parse special meta tag */

                 extra_func->read(s, pbx, tlen, tag, extra_meta);

         }

         else if (!tag[0]) {
             if (tag[1])

                 av_log(s, AV_LOG_WARNING, "invalid frame id, assuming padding\n");

             avio_skip(s->pb, tlen);

             break;
         }

         /* Skip to end of tag */

 seek:

         avio_seek(s->pb, next, SEEK_SET);

     }
 

     if (version == 4 && flags & 0x10) /* Footer preset, always 10 bytes, skip over it */

         end += 10;

 
   error:

     if (reason)
         av_log(s, AV_LOG_INFO, "ID3v2.%d tag skipped, cannot handle %s\n", version, reason);

     avio_seek(s->pb, end, SEEK_SET);

     av_free(buffer);

     av_free(uncompressed_buffer);

     return;
 }

 void ff_id3v2_read(AVFormatContext *s, const char *magic, ID3v2ExtraMeta **extra_meta)

 {
     int len, ret;
     uint8_t buf[ID3v2_HEADER_SIZE];
     int     found_header;
     int64_t off;
 
     do {
         /* save the current offset in case there's nothing to read/skip */

         off = avio_tell(s->pb);

         ret = avio_read(s->pb, buf, ID3v2_HEADER_SIZE);

         if (ret != ID3v2_HEADER_SIZE)

             break;

             found_header = ff_id3v2_match(buf, magic);
             if (found_header) {
             /* parse ID3v2 header */
             len = ((buf[6] & 0x7f) << 21) |
                   ((buf[7] & 0x7f) << 14) |
                   ((buf[8] & 0x7f) << 7) |
                    (buf[9] & 0x7f);

             ff_id3v2_parse(s, len, buf[3], buf[5], extra_meta);

         } else {

             avio_seek(s->pb, off, SEEK_SET);

         }
     } while (found_header);

     ff_metadata_conv(&s->metadata, NULL, ff_id3v2_34_metadata_conv);

     ff_metadata_conv(&s->metadata, NULL, id3v2_2_metadata_conv);

     ff_metadata_conv(&s->metadata, NULL, ff_id3v2_4_metadata_conv);

     merge_date(&s->metadata);

 }
 

 void ff_id3v2_free_extra_meta(ID3v2ExtraMeta **extra_meta)
 {
     ID3v2ExtraMeta *current = *extra_meta, *next;

     const ID3v2EMFunc *extra_func;

 
     while (current) {

         if ((extra_func = get_extra_meta_func(current->tag, 1)))
             extra_func->free(current->data);

         next = current->next;
         av_freep(&current);
         current = next;
     }
 }

 
 int ff_id3v2_parse_apic(AVFormatContext *s, ID3v2ExtraMeta **extra_meta)
 {
     ID3v2ExtraMeta *cur;
 
     for (cur = *extra_meta; cur; cur = cur->next) {
         ID3v2ExtraMetaAPIC *apic;
         AVStream *st;
 
         if (strcmp(cur->tag, "APIC"))
             continue;
         apic = cur->data;
 
         if (!(st = avformat_new_stream(s, NULL)))
             return AVERROR(ENOMEM);
 
         st->disposition      |= AV_DISPOSITION_ATTACHED_PIC;
         st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
         st->codec->codec_id   = apic->id;
         av_dict_set(&st->metadata, "title",   apic->description, 0);
         av_dict_set(&st->metadata, "comment", apic->type, 0);
 
         av_init_packet(&st->attached_pic);
         st->attached_pic.data         = apic->data;
         st->attached_pic.size         = apic->len;
         st->attached_pic.destruct     = av_destruct_packet;
         st->attached_pic.stream_index = st->index;

         st->attached_pic.flags       |= AV_PKT_FLAG_KEY;

 
         apic->data = NULL;
         apic->len  = 0;
     }
 
     return 0;
 }