root/libavcodec/wma.c

DEFINITIONS

1. init_coef_vlc
2. ff_wma_init
3. ff_wma_total_gain_to_bits
4. ff_wma_end
5. ff_wma_get_large_val
6. ff_wma_run_level_decode

/*
 * WMA compatible codec
 * Copyright (c) 2002-2007 The FFmpeg Project
 *
 * 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 "libavutil/attributes.h"

#include "avcodec.h"
#include "internal.h"
#include "sinewin.h"
#include "wma.h"
#include "wma_common.h"
#include "wma_freqs.h"
#include "wmadata.h"

/* XXX: use same run/length optimization as mpeg decoders */
// FIXME maybe split decode / encode or pass flag
static av_cold int init_coef_vlc(VLC *vlc, uint16_t **prun_table,
                                 float **plevel_table, uint16_t **pint_table,
                                 const CoefVLCTable *vlc_table)
{
    int n                        = vlc_table->n;
    const uint8_t  *table_bits   = vlc_table->huffbits;
    const uint32_t *table_codes  = vlc_table->huffcodes;
    const uint16_t *levels_table = vlc_table->levels;
    uint16_t *run_table, *level_table, *int_table;
    float *flevel_table;
    int i, l, j, k, level;

    init_vlc(vlc, VLCBITS, n, table_bits, 1, 1, table_codes, 4, 4, 0);

    run_table    = av_malloc_array(n, sizeof(uint16_t));
    level_table  = av_malloc_array(n, sizeof(uint16_t));
    flevel_table = av_malloc_array(n, sizeof(*flevel_table));
    int_table    = av_malloc_array(n, sizeof(uint16_t));
    if (!run_table || !level_table || !flevel_table || !int_table) {
        av_freep(&run_table);
        av_freep(&level_table);
        av_freep(&flevel_table);
        av_freep(&int_table);
        return AVERROR(ENOMEM);
    }
    i            = 2;
    level        = 1;
    k            = 0;
    while (i < n) {
        int_table[k] = i;
        l            = levels_table[k++];
        for (j = 0; j < l; j++) {
            run_table[i]    = j;
            level_table[i]  = level;
            flevel_table[i] = level;
            i++;
        }
        level++;
    }
    *prun_table   = run_table;
    *plevel_table = flevel_table;
    *pint_table   = int_table;
    av_free(level_table);

    return 0;
}

av_cold int ff_wma_init(AVCodecContext *avctx, int flags2)
{
    WMACodecContext *s = avctx->priv_data;
    int i, ret;
    float bps1, high_freq;
    volatile float bps;
    int sample_rate1;
    int coef_vlc_table;

    if (avctx->sample_rate <= 0 || avctx->sample_rate > 50000 ||
        avctx->channels    <= 0 || avctx->channels    > 2     ||
        avctx->bit_rate    <= 0)
        return -1;


    if (avctx->codec->id == AV_CODEC_ID_WMAV1)
        s->version = 1;
    else
        s->version = 2;

    /* compute MDCT block size */
    s->frame_len_bits = ff_wma_get_frame_len_bits(avctx->sample_rate,
                                                  s->version, 0);
    s->next_block_len_bits = s->frame_len_bits;
    s->prev_block_len_bits = s->frame_len_bits;
    s->block_len_bits      = s->frame_len_bits;

    s->frame_len = 1 << s->frame_len_bits;
    if (s->use_variable_block_len) {
        int nb_max, nb;
        nb = ((flags2 >> 3) & 3) + 1;
        if ((avctx->bit_rate / avctx->channels) >= 32000)
            nb += 2;
        nb_max = s->frame_len_bits - BLOCK_MIN_BITS;
        if (nb > nb_max)
            nb = nb_max;
        s->nb_block_sizes = nb + 1;
    } else
        s->nb_block_sizes = 1;

    /* init rate dependent parameters */
    s->use_noise_coding = 1;
    high_freq           = avctx->sample_rate * 0.5;

    /* if version 2, then the rates are normalized */
    sample_rate1 = avctx->sample_rate;
    if (s->version == 2) {
        if (sample_rate1 >= 44100)
            sample_rate1 = 44100;
        else if (sample_rate1 >= 22050)
            sample_rate1 = 22050;
        else if (sample_rate1 >= 16000)
            sample_rate1 = 16000;
        else if (sample_rate1 >= 11025)
            sample_rate1 = 11025;
        else if (sample_rate1 >= 8000)
            sample_rate1 = 8000;
    }

    bps                 = (float) avctx->bit_rate /
                          (float) (avctx->channels * avctx->sample_rate);
    s->byte_offset_bits = av_log2((int) (bps * s->frame_len / 8.0 + 0.5)) + 2;
    if (s->byte_offset_bits + 3 > MIN_CACHE_BITS) {
        av_log(avctx, AV_LOG_ERROR, "byte_offset_bits %d is too large\n", s->byte_offset_bits);
        return AVERROR_PATCHWELCOME;
    }

    /* compute high frequency value and choose if noise coding should
     * be activated */
    bps1 = bps;
    if (avctx->channels == 2)
        bps1 = bps * 1.6;
    if (sample_rate1 == 44100) {
        if (bps1 >= 0.61)
            s->use_noise_coding = 0;
        else
            high_freq = high_freq * 0.4;
    } else if (sample_rate1 == 22050) {
        if (bps1 >= 1.16)
            s->use_noise_coding = 0;
        else if (bps1 >= 0.72)
            high_freq = high_freq * 0.7;
        else
            high_freq = high_freq * 0.6;
    } else if (sample_rate1 == 16000) {
        if (bps > 0.5)
            high_freq = high_freq * 0.5;
        else
            high_freq = high_freq * 0.3;
    } else if (sample_rate1 == 11025)
        high_freq = high_freq * 0.7;
    else if (sample_rate1 == 8000) {
        if (bps <= 0.625)
            high_freq = high_freq * 0.5;
        else if (bps > 0.75)
            s->use_noise_coding = 0;
        else
            high_freq = high_freq * 0.65;
    } else {
        if (bps >= 0.8)
            high_freq = high_freq * 0.75;
        else if (bps >= 0.6)
            high_freq = high_freq * 0.6;
        else
            high_freq = high_freq * 0.5;
    }
    ff_dlog(s->avctx, "flags2=0x%x\n", flags2);
    ff_dlog(s->avctx, "version=%d channels=%d sample_rate=%d bitrate=%"PRId64" block_align=%d\n",
            s->version, avctx->channels, avctx->sample_rate, avctx->bit_rate,
            avctx->block_align);
    ff_dlog(s->avctx, "bps=%f bps1=%f high_freq=%f bitoffset=%d\n",
            bps, bps1, high_freq, s->byte_offset_bits);
    ff_dlog(s->avctx, "use_noise_coding=%d use_exp_vlc=%d nb_block_sizes=%d\n",
            s->use_noise_coding, s->use_exp_vlc, s->nb_block_sizes);

    /* compute the scale factor band sizes for each MDCT block size */
    {
        int a, b, pos, lpos, k, block_len, i, j, n;
        const uint8_t *table;

        if (s->version == 1)
            s->coefs_start = 3;
        else
            s->coefs_start = 0;
        for (k = 0; k < s->nb_block_sizes; k++) {
            block_len = s->frame_len >> k;

            if (s->version == 1) {
                lpos = 0;
                for (i = 0; i < 25; i++) {
                    a   = ff_wma_critical_freqs[i];
                    b   = avctx->sample_rate;
                    pos = ((block_len * 2 * a) + (b >> 1)) / b;
                    if (pos > block_len)
                        pos = block_len;
                    s->exponent_bands[0][i] = pos - lpos;
                    if (pos >= block_len) {
                        i++;
                        break;
                    }
                    lpos = pos;
                }
                s->exponent_sizes[0] = i;
            } else {
                /* hardcoded tables */
                table = NULL;
                a     = s->frame_len_bits - BLOCK_MIN_BITS - k;
                if (a < 3) {
                    if (avctx->sample_rate >= 44100)
                        table = exponent_band_44100[a];
                    else if (avctx->sample_rate >= 32000)
                        table = exponent_band_32000[a];
                    else if (avctx->sample_rate >= 22050)
                        table = exponent_band_22050[a];
                }
                if (table) {
                    n = *table++;
                    for (i = 0; i < n; i++)
                        s->exponent_bands[k][i] = table[i];
                    s->exponent_sizes[k] = n;
                } else {
                    j    = 0;
                    lpos = 0;
                    for (i = 0; i < 25; i++) {
                        a     = ff_wma_critical_freqs[i];
                        b     = avctx->sample_rate;
                        pos   = ((block_len * 2 * a) + (b << 1)) / (4 * b);
                        pos <<= 2;
                        if (pos > block_len)
                            pos = block_len;
                        if (pos > lpos)
                            s->exponent_bands[k][j++] = pos - lpos;
                        if (pos >= block_len)
                            break;
                        lpos = pos;
                    }
                    s->exponent_sizes[k] = j;
                }
            }

            /* max number of coefs */
            s->coefs_end[k] = (s->frame_len - ((s->frame_len * 9) / 100)) >> k;
            /* high freq computation */
            s->high_band_start[k] = (int) ((block_len * 2 * high_freq) /
                                           avctx->sample_rate + 0.5);
            n   = s->exponent_sizes[k];
            j   = 0;
            pos = 0;
            for (i = 0; i < n; i++) {
                int start, end;
                start = pos;
                pos  += s->exponent_bands[k][i];
                end   = pos;
                if (start < s->high_band_start[k])
                    start = s->high_band_start[k];
                if (end > s->coefs_end[k])
                    end = s->coefs_end[k];
                if (end > start)
                    s->exponent_high_bands[k][j++] = end - start;
            }
            s->exponent_high_sizes[k] = j;
        }
    }

#ifdef TRACE
    {
        int i, j;
        for (i = 0; i < s->nb_block_sizes; i++) {
            ff_tlog(s->avctx, "%5d: n=%2d:",
                    s->frame_len >> i,
                    s->exponent_sizes[i]);
            for (j = 0; j < s->exponent_sizes[i]; j++)
                ff_tlog(s->avctx, " %d", s->exponent_bands[i][j]);
            ff_tlog(s->avctx, "\n");
        }
    }
#endif /* TRACE */

    /* init MDCT windows : simple sine window */
    for (i = 0; i < s->nb_block_sizes; i++) {
        ff_init_ff_sine_windows(s->frame_len_bits - i);
        s->windows[i] = ff_sine_windows[s->frame_len_bits - i];
    }

    s->reset_block_lengths = 1;

    if (s->use_noise_coding) {
        /* init the noise generator */
        if (s->use_exp_vlc)
            s->noise_mult = 0.02;
        else
            s->noise_mult = 0.04;

#ifdef TRACE
        for (i = 0; i < NOISE_TAB_SIZE; i++)
            s->noise_table[i] = 1.0 * s->noise_mult;
#else
        {
            unsigned int seed;
            float norm;
            seed = 1;
            norm = (1.0 / (float) (1LL << 31)) * sqrt(3) * s->noise_mult;
            for (i = 0; i < NOISE_TAB_SIZE; i++) {
                seed              = seed * 314159 + 1;
                s->noise_table[i] = (float) ((int) seed) * norm;
            }
        }
#endif /* TRACE */
    }

    s->fdsp = avpriv_float_dsp_alloc(avctx->flags & AV_CODEC_FLAG_BITEXACT);
    if (!s->fdsp)
        return AVERROR(ENOMEM);

    /* choose the VLC tables for the coefficients */
    coef_vlc_table = 2;
    if (avctx->sample_rate >= 32000) {
        if (bps1 < 0.72)
            coef_vlc_table = 0;
        else if (bps1 < 1.16)
            coef_vlc_table = 1;
    }
    s->coef_vlcs[0] = &coef_vlcs[coef_vlc_table * 2];
    s->coef_vlcs[1] = &coef_vlcs[coef_vlc_table * 2 + 1];
    ret = init_coef_vlc(&s->coef_vlc[0], &s->run_table[0], &s->level_table[0],
                        &s->int_table[0], s->coef_vlcs[0]);
    if (ret < 0)
        return ret;

    return init_coef_vlc(&s->coef_vlc[1], &s->run_table[1], &s->level_table[1],
                         &s->int_table[1], s->coef_vlcs[1]);
}

int ff_wma_total_gain_to_bits(int total_gain)
{
    if (total_gain < 15)
        return 13;
    else if (total_gain < 32)
        return 12;
    else if (total_gain < 40)
        return 11;
    else if (total_gain < 45)
        return 10;
    else
        return  9;
}

int ff_wma_end(AVCodecContext *avctx)
{
    WMACodecContext *s = avctx->priv_data;
    int i;

    for (i = 0; i < s->nb_block_sizes; i++)
        ff_mdct_end(&s->mdct_ctx[i]);

    if (s->use_exp_vlc)
        ff_free_vlc(&s->exp_vlc);
    if (s->use_noise_coding)
        ff_free_vlc(&s->hgain_vlc);
    for (i = 0; i < 2; i++) {
        ff_free_vlc(&s->coef_vlc[i]);
        av_freep(&s->run_table[i]);
        av_freep(&s->level_table[i]);
        av_freep(&s->int_table[i]);
    }
    av_freep(&s->fdsp);

    return 0;
}

/**
 * Decode an uncompressed coefficient.
 * @param gb GetBitContext
 * @return the decoded coefficient
 */
unsigned int ff_wma_get_large_val(GetBitContext *gb)
{
    /** consumes up to 34 bits */
    int n_bits = 8;
    /** decode length */
    if (get_bits1(gb)) {
        n_bits += 8;
        if (get_bits1(gb)) {
            n_bits += 8;
            if (get_bits1(gb))
                n_bits += 7;
        }
    }
    return get_bits_long(gb, n_bits);
}

/**
 * Decode run level compressed coefficients.
 * @param avctx codec context
 * @param gb bitstream reader context
 * @param vlc vlc table for get_vlc2
 * @param level_table level codes
 * @param run_table run codes
 * @param version 0 for wma1,2 1 for wmapro
 * @param ptr output buffer
 * @param offset offset in the output buffer
 * @param num_coefs number of input coefficients
 * @param block_len input buffer length (2^n)
 * @param frame_len_bits number of bits for escaped run codes
 * @param coef_nb_bits number of bits for escaped level codes
 * @return 0 on success, -1 otherwise
 */
int ff_wma_run_level_decode(AVCodecContext *avctx, GetBitContext *gb,
                            VLC *vlc, const float *level_table,
                            const uint16_t *run_table, int version,
                            WMACoef *ptr, int offset, int num_coefs,
                            int block_len, int frame_len_bits,
                            int coef_nb_bits)
{
    int code, level, sign;
    const uint32_t *ilvl = (const uint32_t *) level_table;
    uint32_t *iptr = (uint32_t *) ptr;
    const unsigned int coef_mask = block_len - 1;
    for (; offset < num_coefs; offset++) {
        code = get_vlc2(gb, vlc->table, VLCBITS, VLCMAX);
        if (code > 1) {
            /** normal code */
            offset                  += run_table[code];
            sign                     = get_bits1(gb) - 1;
            iptr[offset & coef_mask] = ilvl[code] ^ (sign & 0x80000000);
        } else if (code == 1) {
            /** EOB */
            break;
        } else {
            /** escape */
            if (!version) {
                level = get_bits(gb, coef_nb_bits);
                /** NOTE: this is rather suboptimal. reading
                 *  block_len_bits would be better */
                offset += get_bits(gb, frame_len_bits);
            } else {
                level = ff_wma_get_large_val(gb);
                /** escape decode */
                if (get_bits1(gb)) {
                    if (get_bits1(gb)) {
                        if (get_bits1(gb)) {
                            av_log(avctx, AV_LOG_ERROR,
                                   "broken escape sequence\n");
                            return -1;
                        } else
                            offset += get_bits(gb, frame_len_bits) + 4;
                    } else
                        offset += get_bits(gb, 2) + 1;
                }
            }
            sign                    = get_bits1(gb) - 1;
            ptr[offset & coef_mask] = (level ^ sign) - sign;
        }
    }
    /** NOTE: EOB can be omitted */
    if (offset > num_coefs) {
        av_log(avctx, AV_LOG_ERROR,
               "overflow (%d > %d) in spectral RLE, ignoring\n",
               offset,
               num_coefs
              );
        return -1;
    }

    return 0;
}