FFmpeg/libavformat/id3v2.c

/*
 * ID3v2 header parser
 * 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
 */

#include "id3v2.h"

int ff_id3v2_match(const uint8_t *buf)
{
    return  buf[0] == 'I' &&
            buf[1] == 'D' &&
            buf[2] == '3' &&
            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;
}