ffmpeg / libavcodec / vorbis.c @ 9106a698
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/**


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* @file libavcodec/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 021101301 USA

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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 "get_bits.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<n1;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<<(j1)); 
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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(vorbis_floor1_entry * 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) { 
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int dy = y1  y0;

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int adx = x1  x0;

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int base = dy / adx;

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int ady = FFABS(dy)  FFABS(base) * 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 = dy<0 ? 1 : 1; 
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buf[x] = ff_vorbis_floor1_inverse_db_table[y]; 
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while (++x < x1) {

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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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} 
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y += base; 
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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(vorbis_floor1_entry * 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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int x1 = list[pos].x;

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int y1 = y_list[pos] * multiplier;

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if (lx < samples)

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render_line(lx, ly, FFMIN(x1,samples), y1, out); 
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lx = x1; 
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ly = y1; 
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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);

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} 