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ffmpeg / libavformat / id3v2.c @ 1d4b1bf2

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/*
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 * ID3v2 header parser
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 * Copyright (c) 2003 Fabrice Bellard
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 *
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 * This file is part of FFmpeg.
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 *
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 * FFmpeg is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2.1 of the License, or (at your option) any later version.
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 *
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 * FFmpeg is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with FFmpeg; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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 */
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#include "id3v2.h"
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#include "id3v1.h"
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#include "libavutil/avstring.h"
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int ff_id3v2_match(const uint8_t *buf)
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{
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    return  buf[0]         ==  'I' &&
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            buf[1]         ==  'D' &&
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            buf[2]         ==  '3' &&
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            buf[3]         != 0xff &&
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            buf[4]         != 0xff &&
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           (buf[6] & 0x80) ==    0 &&
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           (buf[7] & 0x80) ==    0 &&
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           (buf[8] & 0x80) ==    0 &&
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           (buf[9] & 0x80) ==    0;
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}
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int ff_id3v2_tag_len(const uint8_t * buf)
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{
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    int len = ((buf[6] & 0x7f) << 21) +
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              ((buf[7] & 0x7f) << 14) +
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              ((buf[8] & 0x7f) << 7) +
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               (buf[9] & 0x7f) +
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              ID3v2_HEADER_SIZE;
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    if (buf[5] & 0x10)
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        len += ID3v2_HEADER_SIZE;
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    return len;
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}
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static unsigned int get_size(ByteIOContext *s, int len)
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{
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    int v = 0;
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    while (len--)
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        v = (v << 7) + (get_byte(s) & 0x7F);
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    return v;
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}
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static void read_ttag(AVFormatContext *s, int taglen, const char *key)
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{
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    char *q, dst[512];
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    int len, dstlen = sizeof(dst) - 1;
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    unsigned genre;
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    dst[0] = 0;
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    if (taglen < 1)
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        return;
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    taglen--; /* account for encoding type byte */
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    switch (get_byte(s->pb)) { /* encoding type */
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    case 0:  /* ISO-8859-1 (0 - 255 maps directly into unicode) */
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        q = dst;
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        while (taglen--) {
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            uint8_t tmp;
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            PUT_UTF8(get_byte(s->pb), tmp, if (q - dst < dstlen - 1) *q++ = tmp;)
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        }
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        *q = '\0';
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        break;
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    case 3:  /* UTF-8 */
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        len = FFMIN(taglen, dstlen - 1);
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        get_buffer(s->pb, dst, len);
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        dst[len] = 0;
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        break;
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    }
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    if (!strcmp(key, "genre")
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        && (sscanf(dst, "(%d)", &genre) == 1 || sscanf(dst, "%d", &genre) == 1)
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        && genre <= ID3v1_GENRE_MAX)
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        av_strlcpy(dst, ff_id3v1_genre_str[genre], sizeof(dst));
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    if (*dst)
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        av_metadata_set(&s->metadata, key, dst);
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}
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void ff_id3v2_parse(AVFormatContext *s, int len, uint8_t version, uint8_t flags)
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{
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    int isv34, tlen;
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    uint32_t tag;
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    int64_t next;
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    int taghdrlen;
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    const char *reason;
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    switch (version) {
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    case 2:
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        if (flags & 0x40) {
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            reason = "compression";
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            goto error;
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        }
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        isv34 = 0;
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        taghdrlen = 6;
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        break;
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    case 3:
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    case 4:
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        isv34 = 1;
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        taghdrlen = 10;
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        break;
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    default:
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        reason = "version";
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        goto error;
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    }
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    if (flags & 0x80) {
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        reason = "unsynchronization";
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        goto error;
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    }
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    if (isv34 && flags & 0x40) /* Extended header present, just skip over it */
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        url_fskip(s->pb, get_size(s->pb, 4));
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    while (len >= taghdrlen) {
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        if (isv34) {
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            tag  = get_be32(s->pb);
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            tlen = get_size(s->pb, 4);
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            get_be16(s->pb); /* flags */
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        } else {
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            tag  = get_be24(s->pb);
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            tlen = get_size(s->pb, 3);
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        }
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        len -= taghdrlen + tlen;
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        if (len < 0)
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            break;
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        next = url_ftell(s->pb) + tlen;
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        switch (tag) {
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        case MKBETAG('T', 'I', 'T', '2'):
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        case MKBETAG(0,   'T', 'T', '2'):
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            read_ttag(s, tlen, "title");
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            break;
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        case MKBETAG('T', 'P', 'E', '1'):
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        case MKBETAG(0,   'T', 'P', '1'):
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            read_ttag(s, tlen, "author");
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            break;
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        case MKBETAG('T', 'A', 'L', 'B'):
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        case MKBETAG(0,   'T', 'A', 'L'):
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            read_ttag(s, tlen, "album");
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            break;
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        case MKBETAG('T', 'C', 'O', 'N'):
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        case MKBETAG(0,   'T', 'C', 'O'):
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            read_ttag(s, tlen, "genre");
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            break;
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        case MKBETAG('T', 'C', 'O', 'P'):
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        case MKBETAG(0,   'T', 'C', 'R'):
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            read_ttag(s, tlen, "copyright");
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            break;
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        case MKBETAG('T', 'R', 'C', 'K'):
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        case MKBETAG(0,   'T', 'R', 'K'):
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            read_ttag(s, tlen, "track");
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            break;
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        case 0:
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            /* padding, skip to end */
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            url_fskip(s->pb, len);
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            len = 0;
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            continue;
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        }
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        /* Skip to end of tag */
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        url_fseek(s->pb, next, SEEK_SET);
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    }
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    if (version == 4 && flags & 0x10) /* Footer preset, always 10 bytes, skip over it */
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        url_fskip(s->pb, 10);
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    return;
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  error:
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    av_log(s, AV_LOG_INFO, "ID3v2.%d tag skipped, cannot handle %s\n", version, reason);
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    url_fskip(s->pb, len);
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}