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ffmpeg / libavcodec / vorbis.c @ 07c55d8e

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/**
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 * @file vorbis.c
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 * Common code for Vorbis I encoder and decoder
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 * @author Denes Balatoni  ( dbalatoni programozo hu )
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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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 */
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#undef V_DEBUG
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//#define V_DEBUG
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#define ALT_BITSTREAM_READER_LE
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#include "avcodec.h"
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#include "bitstream.h"
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#include "vorbis.h"
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/* Helper functions */
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unsigned int ff_vorbis_nth_root(unsigned int x, unsigned int n) {   // x^(1/n)
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    unsigned int ret=0, i, j;
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    do {
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        ++ret;
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        for(i=0,j=ret;i<n-1;i++) j*=ret;
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    } while (j<=x);
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    return (ret-1);
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}
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// Generate vlc codes from vorbis huffman code lengths
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int ff_vorbis_len2vlc(uint8_t *bits, uint32_t *codes, uint_fast32_t num) {
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    uint_fast32_t exit_at_level[33]={404,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
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        0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
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    uint_fast8_t i,j;
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    uint_fast32_t code,p;
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#ifdef V_DEBUG
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    GetBitContext gb;
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#endif
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    for(p=0;(bits[p]==0) && (p<num);++p);
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    if (p==num) {
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//        av_log(vc->avccontext, AV_LOG_INFO, "An empty codebook. Heh?! \n");
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        return 0;
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    }
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    codes[p]=0;
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    for(i=0;i<bits[p];++i) {
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        exit_at_level[i+1]=1<<i;
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    }
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#ifdef V_DEBUG
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    av_log(NULL, AV_LOG_INFO, " %d. of %d code len %d code %d - ", p, num, bits[p], codes[p]);
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    init_get_bits(&gb, (uint_fast8_t *)&codes[p], bits[p]);
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    for(i=0;i<bits[p];++i) {
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        av_log(NULL, AV_LOG_INFO, "%s", get_bits1(&gb) ? "1" : "0");
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    }
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    av_log(NULL, AV_LOG_INFO, "\n");
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#endif
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    ++p;
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    for(;p<num;++p) {
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        if (bits[p]==0) continue;
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        // find corresponding exit(node which the tree can grow further from)
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        for(i=bits[p];i>0;--i) {
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            if (exit_at_level[i]) break;
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        }
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        if (!i) return 1; // overspecified tree
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        code=exit_at_level[i];
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        exit_at_level[i]=0;
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        // construct code (append 0s to end) and introduce new exits
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        for(j=i+1;j<=bits[p];++j) {
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            exit_at_level[j]=code+(1<<(j-1));
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        }
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        codes[p]=code;
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#ifdef V_DEBUG
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        av_log(NULL, AV_LOG_INFO, " %d. code len %d code %d - ", p, bits[p], codes[p]);
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        init_get_bits(&gb, (uint_fast8_t *)&codes[p], bits[p]);
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        for(i=0;i<bits[p];++i) {
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            av_log(NULL, AV_LOG_INFO, "%s", get_bits1(&gb) ? "1" : "0");
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        }
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        av_log(NULL, AV_LOG_INFO, "\n");
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#endif
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    }
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    //no exits should be left (underspecified tree - ie. unused valid vlcs - not allowed by SPEC)
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    for (p=1; p<33; p++)
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        if (exit_at_level[p]) return 1;
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    return 0;
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}
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void ff_vorbis_ready_floor1_list(floor1_entry_t * list, int values) {
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    int i;
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    list[0].sort = 0;
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    list[1].sort = 1;
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    for (i = 2; i < values; i++) {
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        int j;
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        list[i].low = 0;
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        list[i].high = 1;
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        list[i].sort = i;
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        for (j = 2; j < i; j++) {
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            int tmp = list[j].x;
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            if (tmp < list[i].x) {
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                if (tmp > list[list[i].low].x) list[i].low = j;
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            } else {
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                if (tmp < list[list[i].high].x) list[i].high = j;
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            }
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        }
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    }
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    for (i = 0; i < values - 1; i++) {
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        int j;
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        for (j = i + 1; j < values; j++) {
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            if (list[list[i].sort].x > list[list[j].sort].x) {
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                int tmp = list[i].sort;
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                list[i].sort = list[j].sort;
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                list[j].sort = tmp;
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            }
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        }
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    }
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}
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static void render_line(int x0, int y0, int x1, int y1, float * buf, int n) {
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    int dy = y1 - y0;
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    int adx = x1 - x0;
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    int ady = FFABS(dy);
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    int base = dy / adx;
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    int x = x0;
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    int y = y0;
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    int err = 0;
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    int sy;
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    if (dy < 0) sy = base - 1;
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    else        sy = base + 1;
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    ady = ady - FFABS(base) * adx;
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    if (x >= n) return;
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    buf[x] = ff_vorbis_floor1_inverse_db_table[y];
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    for (x = x0 + 1; x < x1; x++) {
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        if (x >= n) return;
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        err += ady;
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        if (err >= adx) {
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            err -= adx;
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            y += sy;
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        } else {
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            y += base;
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        }
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        buf[x] = ff_vorbis_floor1_inverse_db_table[y];
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    }
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}
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void ff_vorbis_floor1_render_list(floor1_entry_t * list, int values, uint_fast16_t * y_list, int * flag, int multiplier, float * out, int samples) {
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    int lx, ly, i;
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    lx = 0;
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    ly = y_list[0] * multiplier;
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    for (i = 1; i < values; i++) {
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        int pos = list[i].sort;
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        if (flag[pos]) {
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            render_line(lx, ly, list[pos].x, y_list[pos] * multiplier, out, samples);
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            lx = list[pos].x;
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            ly = y_list[pos] * multiplier;
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        }
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        if (lx >= samples) break;
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    }
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    if (lx < samples) render_line(lx, ly, samples, ly, out, samples);
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}