1/**
2 * @file libavcodec/vorbis.c
3 * Common code for Vorbis I encoder and decoder
4 * @author Denes Balatoni  ( dbalatoni programozo hu )
5
6 * This file is part of FFmpeg.
7 *
8 * FFmpeg is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
12 *
13 * FFmpeg is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
16 * Lesser General Public License for more details.
17 *
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with FFmpeg; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21 */
22
23#undef V_DEBUG
24//#define V_DEBUG
25
26#define ALT_BITSTREAM_READER_LE
27#include "avcodec.h"
28#include "bitstream.h"
29
30#include "vorbis.h"
31
32
33/* Helper functions */
34
35unsigned int ff_vorbis_nth_root(unsigned int x, unsigned int n) {   // x^(1/n)
36    unsigned int ret=0, i, j;
37
38    do {
39        ++ret;
40        for(i=0,j=ret;i<n-1;i++) j*=ret;
41    } while (j<=x);
42
43    return ret - 1;
44}
45
46// Generate vlc codes from vorbis huffman code lengths
47
48// the two bits[p] > 32 checks should be redundant, all calling code should
49// already ensure that, but since it allows overwriting the stack it seems
50// reasonable to check redundantly.
51int ff_vorbis_len2vlc(uint8_t *bits, uint32_t *codes, uint_fast32_t num) {
52    uint_fast32_t exit_at_level[33]={404,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
53        0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
54
55    uint_fast8_t i,j;
56    uint_fast32_t code,p;
57
58#ifdef V_DEBUG
59    GetBitContext gb;
60#endif
61
62    for(p=0;(bits[p]==0) && (p<num);++p);
63    if (p==num) {
64//        av_log(vc->avccontext, AV_LOG_INFO, "An empty codebook. Heh?! \n");
65        return 0;
66    }
67
68    codes[p]=0;
69    if (bits[p] > 32) return 1;
70    for(i=0;i<bits[p];++i) {
71        exit_at_level[i+1]=1<<i;
72    }
73
74#ifdef V_DEBUG
75    av_log(NULL, AV_LOG_INFO, " %d. of %d code len %d code %d - ", p, num, bits[p], codes[p]);
76    init_get_bits(&gb, (uint_fast8_t *)&codes[p], bits[p]);
77    for(i=0;i<bits[p];++i) {
78        av_log(NULL, AV_LOG_INFO, "%s", get_bits1(&gb) ? "1" : "0");
79    }
80    av_log(NULL, AV_LOG_INFO, "\n");
81#endif
82
83    ++p;
84
85    for(;p<num;++p) {
86        if (bits[p] > 32) return 1;
87        if (bits[p]==0) continue;
88        // find corresponding exit(node which the tree can grow further from)
89        for(i=bits[p];i>0;--i) {
90            if (exit_at_level[i]) break;
91        }
92        if (!i) return 1; // overspecified tree
93        code=exit_at_level[i];
94        exit_at_level[i]=0;
95        // construct code (append 0s to end) and introduce new exits
96        for(j=i+1;j<=bits[p];++j) {
97            exit_at_level[j]=code+(1<<(j-1));
98        }
99        codes[p]=code;
100
101#ifdef V_DEBUG
102        av_log(NULL, AV_LOG_INFO, " %d. code len %d code %d - ", p, bits[p], codes[p]);
103        init_get_bits(&gb, (uint_fast8_t *)&codes[p], bits[p]);
104        for(i=0;i<bits[p];++i) {
105            av_log(NULL, AV_LOG_INFO, "%s", get_bits1(&gb) ? "1" : "0");
106        }
107        av_log(NULL, AV_LOG_INFO, "\n");
108#endif
109
110    }
111
112    //no exits should be left (underspecified tree - ie. unused valid vlcs - not allowed by SPEC)
113    for (p=1; p<33; p++)
114        if (exit_at_level[p]) return 1;
115
116    return 0;
117}
118
119void ff_vorbis_ready_floor1_list(vorbis_floor1_entry * list, int values) {
120    int i;
121    list[0].sort = 0;
122    list[1].sort = 1;
123    for (i = 2; i < values; i++) {
124        int j;
125        list[i].low = 0;
126        list[i].high = 1;
127        list[i].sort = i;
128        for (j = 2; j < i; j++) {
129            int tmp = list[j].x;
130            if (tmp < list[i].x) {
131                if (tmp > list[list[i].low].x) list[i].low = j;
132            } else {
133                if (tmp < list[list[i].high].x) list[i].high = j;
134            }
135        }
136    }
137    for (i = 0; i < values - 1; i++) {
138        int j;
139        for (j = i + 1; j < values; j++) {
140            if (list[list[i].sort].x > list[list[j].sort].x) {
141                int tmp = list[i].sort;
142                list[i].sort = list[j].sort;
143                list[j].sort = tmp;
144            }
145        }
146    }
147}
148
149static void render_line(int x0, int y0, int x1, int y1, float * buf) {
150    int dy = y1 - y0;
151    int adx = x1 - x0;
152    int base = dy / adx;
153    int ady = FFABS(dy) - FFABS(base) * adx;
154    int x = x0;
155    int y = y0;
156    int err = 0;
157    int sy = dy<0 ? -1 : 1;
158    buf[x] = ff_vorbis_floor1_inverse_db_table[y];
159    while (++x < x1) {
160        err += ady;
161        if (err >= adx) {
162            err -= adx;
163            y += sy;
164        }
165        y += base;
166        buf[x] = ff_vorbis_floor1_inverse_db_table[y];
167    }
168}
169
170void ff_vorbis_floor1_render_list(vorbis_floor1_entry * list, int values, uint_fast16_t * y_list, int * flag, int multiplier, float * out, int samples) {
171    int lx, ly, i;
172    lx = 0;
173    ly = y_list[0] * multiplier;
174    for (i = 1; i < values; i++) {
175        int pos = list[i].sort;
176        if (flag[pos]) {
177            int x1 = list[pos].x;
178            int y1 = y_list[pos] * multiplier;
179            if (lx < samples)
180                render_line(lx, ly, FFMIN(x1,samples), y1, out);
181            lx = x1;
182            ly = y1;
183        }
184        if (lx >= samples) break;
185    }
186    if (lx < samples) render_line(lx, ly, samples, ly, out);
187}
188