wma_common.c 1.89 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
/*
 * common code shared by all WMA variants
 *
 * This file is part of Libav.
 *
 * Libav 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.
 *
 * Libav 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 Libav; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include "libavutil/attributes.h"
#include "wma_common.h"

/**
 *@brief Get the samples per frame for this stream.
 *@param sample_rate output sample_rate
 *@param version wma version
 *@param decode_flags codec compression features
 *@return log2 of the number of output samples per frame
 */
31
av_cold int ff_wma_get_frame_len_bits(int sample_rate, int version,
32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62
                                      unsigned int decode_flags)
{

    int frame_len_bits;

    if (sample_rate <= 16000) {
        frame_len_bits = 9;
    } else if (sample_rate <= 22050 ||
             (sample_rate <= 32000 && version == 1)) {
        frame_len_bits = 10;
    } else if (sample_rate <= 48000 || version < 3) {
        frame_len_bits = 11;
    } else if (sample_rate <= 96000) {
        frame_len_bits = 12;
    } else {
        frame_len_bits = 13;
    }

    if (version == 3) {
        int tmp = decode_flags & 0x6;
        if (tmp == 0x2) {
            ++frame_len_bits;
        } else if (tmp == 0x4) {
            --frame_len_bits;
        } else if (tmp == 0x6) {
            frame_len_bits -= 2;
        }
    }

    return frame_len_bits;
}