yading@10: /*
yading@10:  * The simplest mpeg audio layer 2 encoder
yading@10:  * Copyright (c) 2000, 2001 Fabrice Bellard
yading@10:  *
yading@10:  * This file is part of FFmpeg.
yading@10:  *
yading@10:  * FFmpeg is free software; you can redistribute it and/or
yading@10:  * modify it under the terms of the GNU Lesser General Public
yading@10:  * License as published by the Free Software Foundation; either
yading@10:  * version 2.1 of the License, or (at your option) any later version.
yading@10:  *
yading@10:  * FFmpeg is distributed in the hope that it will be useful,
yading@10:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
yading@10:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
yading@10:  * Lesser General Public License for more details.
yading@10:  *
yading@10:  * You should have received a copy of the GNU Lesser General Public
yading@10:  * License along with FFmpeg; if not, write to the Free Software
yading@10:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
yading@10:  */
yading@10: 
yading@10: /**
yading@10:  * @file
yading@10:  * The simplest mpeg audio layer 2 encoder.
yading@10:  */
yading@10: 
yading@10: #include "libavutil/channel_layout.h"
yading@10: 
yading@10: #include "avcodec.h"
yading@10: #include "internal.h"
yading@10: #include "put_bits.h"
yading@10: 
yading@10: #define FRAC_BITS   15   /* fractional bits for sb_samples and dct */
yading@10: #define WFRAC_BITS  14   /* fractional bits for window */
yading@10: 
yading@10: #include "mpegaudio.h"
yading@10: #include "mpegaudiodsp.h"
yading@10: 
yading@10: /* currently, cannot change these constants (need to modify
yading@10:    quantization stage) */
yading@10: #define MUL(a,b) (((int64_t)(a) * (int64_t)(b)) >> FRAC_BITS)
yading@10: 
yading@10: #define SAMPLES_BUF_SIZE 4096
yading@10: 
yading@10: typedef struct MpegAudioContext {
yading@10:     PutBitContext pb;
yading@10:     int nb_channels;
yading@10:     int lsf;           /* 1 if mpeg2 low bitrate selected */
yading@10:     int bitrate_index; /* bit rate */
yading@10:     int freq_index;
yading@10:     int frame_size; /* frame size, in bits, without padding */
yading@10:     /* padding computation */
yading@10:     int frame_frac, frame_frac_incr, do_padding;
yading@10:     short samples_buf[MPA_MAX_CHANNELS][SAMPLES_BUF_SIZE]; /* buffer for filter */
yading@10:     int samples_offset[MPA_MAX_CHANNELS];       /* offset in samples_buf */
yading@10:     int sb_samples[MPA_MAX_CHANNELS][3][12][SBLIMIT];
yading@10:     unsigned char scale_factors[MPA_MAX_CHANNELS][SBLIMIT][3]; /* scale factors */
yading@10:     /* code to group 3 scale factors */
yading@10:     unsigned char scale_code[MPA_MAX_CHANNELS][SBLIMIT];
yading@10:     int sblimit; /* number of used subbands */
yading@10:     const unsigned char *alloc_table;
yading@10: } MpegAudioContext;
yading@10: 
yading@10: /* define it to use floats in quantization (I don't like floats !) */
yading@10: #define USE_FLOATS
yading@10: 
yading@10: #include "mpegaudiodata.h"
yading@10: #include "mpegaudiotab.h"
yading@10: 
yading@10: static av_cold int MPA_encode_init(AVCodecContext *avctx)
yading@10: {
yading@10:     MpegAudioContext *s = avctx->priv_data;
yading@10:     int freq = avctx->sample_rate;
yading@10:     int bitrate = avctx->bit_rate;
yading@10:     int channels = avctx->channels;
yading@10:     int i, v, table;
yading@10:     float a;
yading@10: 
yading@10:     if (channels <= 0 || channels > 2){
yading@10:         av_log(avctx, AV_LOG_ERROR, "encoding %d channel(s) is not allowed in mp2\n", channels);
yading@10:         return AVERROR(EINVAL);
yading@10:     }
yading@10:     bitrate = bitrate / 1000;
yading@10:     s->nb_channels = channels;
yading@10:     avctx->frame_size = MPA_FRAME_SIZE;
yading@10:     avctx->delay      = 512 - 32 + 1;
yading@10: 
yading@10:     /* encoding freq */
yading@10:     s->lsf = 0;
yading@10:     for(i=0;i<3;i++) {
yading@10:         if (avpriv_mpa_freq_tab[i] == freq)
yading@10:             break;
yading@10:         if ((avpriv_mpa_freq_tab[i] / 2) == freq) {
yading@10:             s->lsf = 1;
yading@10:             break;
yading@10:         }
yading@10:     }
yading@10:     if (i == 3){
yading@10:         av_log(avctx, AV_LOG_ERROR, "Sampling rate %d is not allowed in mp2\n", freq);
yading@10:         return AVERROR(EINVAL);
yading@10:     }
yading@10:     s->freq_index = i;
yading@10: 
yading@10:     /* encoding bitrate & frequency */
yading@10:     for(i=0;i<15;i++) {
yading@10:         if (avpriv_mpa_bitrate_tab[s->lsf][1][i] == bitrate)
yading@10:             break;
yading@10:     }
yading@10:     if (i == 15){
yading@10:         av_log(avctx, AV_LOG_ERROR, "bitrate %d is not allowed in mp2\n", bitrate);
yading@10:         return AVERROR(EINVAL);
yading@10:     }
yading@10:     s->bitrate_index = i;
yading@10: 
yading@10:     /* compute total header size & pad bit */
yading@10: 
yading@10:     a = (float)(bitrate * 1000 * MPA_FRAME_SIZE) / (freq * 8.0);
yading@10:     s->frame_size = ((int)a) * 8;
yading@10: 
yading@10:     /* frame fractional size to compute padding */
yading@10:     s->frame_frac = 0;
yading@10:     s->frame_frac_incr = (int)((a - floor(a)) * 65536.0);
yading@10: 
yading@10:     /* select the right allocation table */
yading@10:     table = ff_mpa_l2_select_table(bitrate, s->nb_channels, freq, s->lsf);
yading@10: 
yading@10:     /* number of used subbands */
yading@10:     s->sblimit = ff_mpa_sblimit_table[table];
yading@10:     s->alloc_table = ff_mpa_alloc_tables[table];
yading@10: 
yading@10:     av_dlog(avctx, "%d kb/s, %d Hz, frame_size=%d bits, table=%d, padincr=%x\n",
yading@10:             bitrate, freq, s->frame_size, table, s->frame_frac_incr);
yading@10: 
yading@10:     for(i=0;i<s->nb_channels;i++)
yading@10:         s->samples_offset[i] = 0;
yading@10: 
yading@10:     for(i=0;i<257;i++) {
yading@10:         int v;
yading@10:         v = ff_mpa_enwindow[i];
yading@10: #if WFRAC_BITS != 16
yading@10:         v = (v + (1 << (16 - WFRAC_BITS - 1))) >> (16 - WFRAC_BITS);
yading@10: #endif
yading@10:         filter_bank[i] = v;
yading@10:         if ((i & 63) != 0)
yading@10:             v = -v;
yading@10:         if (i != 0)
yading@10:             filter_bank[512 - i] = v;
yading@10:     }
yading@10: 
yading@10:     for(i=0;i<64;i++) {
yading@10:         v = (int)(exp2((3 - i) / 3.0) * (1 << 20));
yading@10:         if (v <= 0)
yading@10:             v = 1;
yading@10:         scale_factor_table[i] = v;
yading@10: #ifdef USE_FLOATS
yading@10:         scale_factor_inv_table[i] = exp2(-(3 - i) / 3.0) / (float)(1 << 20);
yading@10: #else
yading@10: #define P 15
yading@10:         scale_factor_shift[i] = 21 - P - (i / 3);
yading@10:         scale_factor_mult[i] = (1 << P) * exp2((i % 3) / 3.0);
yading@10: #endif
yading@10:     }
yading@10:     for(i=0;i<128;i++) {
yading@10:         v = i - 64;
yading@10:         if (v <= -3)
yading@10:             v = 0;
yading@10:         else if (v < 0)
yading@10:             v = 1;
yading@10:         else if (v == 0)
yading@10:             v = 2;
yading@10:         else if (v < 3)
yading@10:             v = 3;
yading@10:         else
yading@10:             v = 4;
yading@10:         scale_diff_table[i] = v;
yading@10:     }
yading@10: 
yading@10:     for(i=0;i<17;i++) {
yading@10:         v = ff_mpa_quant_bits[i];
yading@10:         if (v < 0)
yading@10:             v = -v;
yading@10:         else
yading@10:             v = v * 3;
yading@10:         total_quant_bits[i] = 12 * v;
yading@10:     }
yading@10: 
yading@10:     return 0;
yading@10: }
yading@10: 
yading@10: /* 32 point floating point IDCT without 1/sqrt(2) coef zero scaling */
yading@10: static void idct32(int *out, int *tab)
yading@10: {
yading@10:     int i, j;
yading@10:     int *t, *t1, xr;
yading@10:     const int *xp = costab32;
yading@10: 
yading@10:     for(j=31;j>=3;j-=2) tab[j] += tab[j - 2];
yading@10: 
yading@10:     t = tab + 30;
yading@10:     t1 = tab + 2;
yading@10:     do {
yading@10:         t[0] += t[-4];
yading@10:         t[1] += t[1 - 4];
yading@10:         t -= 4;
yading@10:     } while (t != t1);
yading@10: 
yading@10:     t = tab + 28;
yading@10:     t1 = tab + 4;
yading@10:     do {
yading@10:         t[0] += t[-8];
yading@10:         t[1] += t[1-8];
yading@10:         t[2] += t[2-8];
yading@10:         t[3] += t[3-8];
yading@10:         t -= 8;
yading@10:     } while (t != t1);
yading@10: 
yading@10:     t = tab;
yading@10:     t1 = tab + 32;
yading@10:     do {
yading@10:         t[ 3] = -t[ 3];
yading@10:         t[ 6] = -t[ 6];
yading@10: 
yading@10:         t[11] = -t[11];
yading@10:         t[12] = -t[12];
yading@10:         t[13] = -t[13];
yading@10:         t[15] = -t[15];
yading@10:         t += 16;
yading@10:     } while (t != t1);
yading@10: 
yading@10: 
yading@10:     t = tab;
yading@10:     t1 = tab + 8;
yading@10:     do {
yading@10:         int x1, x2, x3, x4;
yading@10: 
yading@10:         x3 = MUL(t[16], FIX(SQRT2*0.5));
yading@10:         x4 = t[0] - x3;
yading@10:         x3 = t[0] + x3;
yading@10: 
yading@10:         x2 = MUL(-(t[24] + t[8]), FIX(SQRT2*0.5));
yading@10:         x1 = MUL((t[8] - x2), xp[0]);
yading@10:         x2 = MUL((t[8] + x2), xp[1]);
yading@10: 
yading@10:         t[ 0] = x3 + x1;
yading@10:         t[ 8] = x4 - x2;
yading@10:         t[16] = x4 + x2;
yading@10:         t[24] = x3 - x1;
yading@10:         t++;
yading@10:     } while (t != t1);
yading@10: 
yading@10:     xp += 2;
yading@10:     t = tab;
yading@10:     t1 = tab + 4;
yading@10:     do {
yading@10:         xr = MUL(t[28],xp[0]);
yading@10:         t[28] = (t[0] - xr);
yading@10:         t[0] = (t[0] + xr);
yading@10: 
yading@10:         xr = MUL(t[4],xp[1]);
yading@10:         t[ 4] = (t[24] - xr);
yading@10:         t[24] = (t[24] + xr);
yading@10: 
yading@10:         xr = MUL(t[20],xp[2]);
yading@10:         t[20] = (t[8] - xr);
yading@10:         t[ 8] = (t[8] + xr);
yading@10: 
yading@10:         xr = MUL(t[12],xp[3]);
yading@10:         t[12] = (t[16] - xr);
yading@10:         t[16] = (t[16] + xr);
yading@10:         t++;
yading@10:     } while (t != t1);
yading@10:     xp += 4;
yading@10: 
yading@10:     for (i = 0; i < 4; i++) {
yading@10:         xr = MUL(tab[30-i*4],xp[0]);
yading@10:         tab[30-i*4] = (tab[i*4] - xr);
yading@10:         tab[   i*4] = (tab[i*4] + xr);
yading@10: 
yading@10:         xr = MUL(tab[ 2+i*4],xp[1]);
yading@10:         tab[ 2+i*4] = (tab[28-i*4] - xr);
yading@10:         tab[28-i*4] = (tab[28-i*4] + xr);
yading@10: 
yading@10:         xr = MUL(tab[31-i*4],xp[0]);
yading@10:         tab[31-i*4] = (tab[1+i*4] - xr);
yading@10:         tab[ 1+i*4] = (tab[1+i*4] + xr);
yading@10: 
yading@10:         xr = MUL(tab[ 3+i*4],xp[1]);
yading@10:         tab[ 3+i*4] = (tab[29-i*4] - xr);
yading@10:         tab[29-i*4] = (tab[29-i*4] + xr);
yading@10: 
yading@10:         xp += 2;
yading@10:     }
yading@10: 
yading@10:     t = tab + 30;
yading@10:     t1 = tab + 1;
yading@10:     do {
yading@10:         xr = MUL(t1[0], *xp);
yading@10:         t1[0] = (t[0] - xr);
yading@10:         t[0] = (t[0] + xr);
yading@10:         t -= 2;
yading@10:         t1 += 2;
yading@10:         xp++;
yading@10:     } while (t >= tab);
yading@10: 
yading@10:     for(i=0;i<32;i++) {
yading@10:         out[i] = tab[bitinv32[i]];
yading@10:     }
yading@10: }
yading@10: 
yading@10: #define WSHIFT (WFRAC_BITS + 15 - FRAC_BITS)
yading@10: 
yading@10: static void filter(MpegAudioContext *s, int ch, const short *samples, int incr)
yading@10: {
yading@10:     short *p, *q;
yading@10:     int sum, offset, i, j;
yading@10:     int tmp[64];
yading@10:     int tmp1[32];
yading@10:     int *out;
yading@10: 
yading@10:     offset = s->samples_offset[ch];
yading@10:     out = &s->sb_samples[ch][0][0][0];
yading@10:     for(j=0;j<36;j++) {
yading@10:         /* 32 samples at once */
yading@10:         for(i=0;i<32;i++) {
yading@10:             s->samples_buf[ch][offset + (31 - i)] = samples[0];
yading@10:             samples += incr;
yading@10:         }
yading@10: 
yading@10:         /* filter */
yading@10:         p = s->samples_buf[ch] + offset;
yading@10:         q = filter_bank;
yading@10:         /* maxsum = 23169 */
yading@10:         for(i=0;i<64;i++) {
yading@10:             sum = p[0*64] * q[0*64];
yading@10:             sum += p[1*64] * q[1*64];
yading@10:             sum += p[2*64] * q[2*64];
yading@10:             sum += p[3*64] * q[3*64];
yading@10:             sum += p[4*64] * q[4*64];
yading@10:             sum += p[5*64] * q[5*64];
yading@10:             sum += p[6*64] * q[6*64];
yading@10:             sum += p[7*64] * q[7*64];
yading@10:             tmp[i] = sum;
yading@10:             p++;
yading@10:             q++;
yading@10:         }
yading@10:         tmp1[0] = tmp[16] >> WSHIFT;
yading@10:         for( i=1; i<=16; i++ ) tmp1[i] = (tmp[i+16]+tmp[16-i]) >> WSHIFT;
yading@10:         for( i=17; i<=31; i++ ) tmp1[i] = (tmp[i+16]-tmp[80-i]) >> WSHIFT;
yading@10: 
yading@10:         idct32(out, tmp1);
yading@10: 
yading@10:         /* advance of 32 samples */
yading@10:         offset -= 32;
yading@10:         out += 32;
yading@10:         /* handle the wrap around */
yading@10:         if (offset < 0) {
yading@10:             memmove(s->samples_buf[ch] + SAMPLES_BUF_SIZE - (512 - 32),
yading@10:                     s->samples_buf[ch], (512 - 32) * 2);
yading@10:             offset = SAMPLES_BUF_SIZE - 512;
yading@10:         }
yading@10:     }
yading@10:     s->samples_offset[ch] = offset;
yading@10: }
yading@10: 
yading@10: static void compute_scale_factors(unsigned char scale_code[SBLIMIT],
yading@10:                                   unsigned char scale_factors[SBLIMIT][3],
yading@10:                                   int sb_samples[3][12][SBLIMIT],
yading@10:                                   int sblimit)
yading@10: {
yading@10:     int *p, vmax, v, n, i, j, k, code;
yading@10:     int index, d1, d2;
yading@10:     unsigned char *sf = &scale_factors[0][0];
yading@10: 
yading@10:     for(j=0;j<sblimit;j++) {
yading@10:         for(i=0;i<3;i++) {
yading@10:             /* find the max absolute value */
yading@10:             p = &sb_samples[i][0][j];
yading@10:             vmax = abs(*p);
yading@10:             for(k=1;k<12;k++) {
yading@10:                 p += SBLIMIT;
yading@10:                 v = abs(*p);
yading@10:                 if (v > vmax)
yading@10:                     vmax = v;
yading@10:             }
yading@10:             /* compute the scale factor index using log 2 computations */
yading@10:             if (vmax > 1) {
yading@10:                 n = av_log2(vmax);
yading@10:                 /* n is the position of the MSB of vmax. now
yading@10:                    use at most 2 compares to find the index */
yading@10:                 index = (21 - n) * 3 - 3;
yading@10:                 if (index >= 0) {
yading@10:                     while (vmax <= scale_factor_table[index+1])
yading@10:                         index++;
yading@10:                 } else {
yading@10:                     index = 0; /* very unlikely case of overflow */
yading@10:                 }
yading@10:             } else {
yading@10:                 index = 62; /* value 63 is not allowed */
yading@10:             }
yading@10: 
yading@10:             av_dlog(NULL, "%2d:%d in=%x %x %d\n",
yading@10:                     j, i, vmax, scale_factor_table[index], index);
yading@10:             /* store the scale factor */
yading@10:             av_assert2(index >=0 && index <= 63);
yading@10:             sf[i] = index;
yading@10:         }
yading@10: 
yading@10:         /* compute the transmission factor : look if the scale factors
yading@10:            are close enough to each other */
yading@10:         d1 = scale_diff_table[sf[0] - sf[1] + 64];
yading@10:         d2 = scale_diff_table[sf[1] - sf[2] + 64];
yading@10: 
yading@10:         /* handle the 25 cases */
yading@10:         switch(d1 * 5 + d2) {
yading@10:         case 0*5+0:
yading@10:         case 0*5+4:
yading@10:         case 3*5+4:
yading@10:         case 4*5+0:
yading@10:         case 4*5+4:
yading@10:             code = 0;
yading@10:             break;
yading@10:         case 0*5+1:
yading@10:         case 0*5+2:
yading@10:         case 4*5+1:
yading@10:         case 4*5+2:
yading@10:             code = 3;
yading@10:             sf[2] = sf[1];
yading@10:             break;
yading@10:         case 0*5+3:
yading@10:         case 4*5+3:
yading@10:             code = 3;
yading@10:             sf[1] = sf[2];
yading@10:             break;
yading@10:         case 1*5+0:
yading@10:         case 1*5+4:
yading@10:         case 2*5+4:
yading@10:             code = 1;
yading@10:             sf[1] = sf[0];
yading@10:             break;
yading@10:         case 1*5+1:
yading@10:         case 1*5+2:
yading@10:         case 2*5+0:
yading@10:         case 2*5+1:
yading@10:         case 2*5+2:
yading@10:             code = 2;
yading@10:             sf[1] = sf[2] = sf[0];
yading@10:             break;
yading@10:         case 2*5+3:
yading@10:         case 3*5+3:
yading@10:             code = 2;
yading@10:             sf[0] = sf[1] = sf[2];
yading@10:             break;
yading@10:         case 3*5+0:
yading@10:         case 3*5+1:
yading@10:         case 3*5+2:
yading@10:             code = 2;
yading@10:             sf[0] = sf[2] = sf[1];
yading@10:             break;
yading@10:         case 1*5+3:
yading@10:             code = 2;
yading@10:             if (sf[0] > sf[2])
yading@10:               sf[0] = sf[2];
yading@10:             sf[1] = sf[2] = sf[0];
yading@10:             break;
yading@10:         default:
yading@10:             av_assert2(0); //cannot happen
yading@10:             code = 0;           /* kill warning */
yading@10:         }
yading@10: 
yading@10:         av_dlog(NULL, "%d: %2d %2d %2d %d %d -> %d\n", j,
yading@10:                 sf[0], sf[1], sf[2], d1, d2, code);
yading@10:         scale_code[j] = code;
yading@10:         sf += 3;
yading@10:     }
yading@10: }
yading@10: 
yading@10: /* The most important function : psycho acoustic module. In this
yading@10:    encoder there is basically none, so this is the worst you can do,
yading@10:    but also this is the simpler. */
yading@10: static void psycho_acoustic_model(MpegAudioContext *s, short smr[SBLIMIT])
yading@10: {
yading@10:     int i;
yading@10: 
yading@10:     for(i=0;i<s->sblimit;i++) {
yading@10:         smr[i] = (int)(fixed_smr[i] * 10);
yading@10:     }
yading@10: }
yading@10: 
yading@10: 
yading@10: #define SB_NOTALLOCATED  0
yading@10: #define SB_ALLOCATED     1
yading@10: #define SB_NOMORE        2
yading@10: 
yading@10: /* Try to maximize the smr while using a number of bits inferior to
yading@10:    the frame size. I tried to make the code simpler, faster and
yading@10:    smaller than other encoders :-) */
yading@10: static void compute_bit_allocation(MpegAudioContext *s,
yading@10:                                    short smr1[MPA_MAX_CHANNELS][SBLIMIT],
yading@10:                                    unsigned char bit_alloc[MPA_MAX_CHANNELS][SBLIMIT],
yading@10:                                    int *padding)
yading@10: {
yading@10:     int i, ch, b, max_smr, max_ch, max_sb, current_frame_size, max_frame_size;
yading@10:     int incr;
yading@10:     short smr[MPA_MAX_CHANNELS][SBLIMIT];
yading@10:     unsigned char subband_status[MPA_MAX_CHANNELS][SBLIMIT];
yading@10:     const unsigned char *alloc;
yading@10: 
yading@10:     memcpy(smr, smr1, s->nb_channels * sizeof(short) * SBLIMIT);
yading@10:     memset(subband_status, SB_NOTALLOCATED, s->nb_channels * SBLIMIT);
yading@10:     memset(bit_alloc, 0, s->nb_channels * SBLIMIT);
yading@10: 
yading@10:     /* compute frame size and padding */
yading@10:     max_frame_size = s->frame_size;
yading@10:     s->frame_frac += s->frame_frac_incr;
yading@10:     if (s->frame_frac >= 65536) {
yading@10:         s->frame_frac -= 65536;
yading@10:         s->do_padding = 1;
yading@10:         max_frame_size += 8;
yading@10:     } else {
yading@10:         s->do_padding = 0;
yading@10:     }
yading@10: 
yading@10:     /* compute the header + bit alloc size */
yading@10:     current_frame_size = 32;
yading@10:     alloc = s->alloc_table;
yading@10:     for(i=0;i<s->sblimit;i++) {
yading@10:         incr = alloc[0];
yading@10:         current_frame_size += incr * s->nb_channels;
yading@10:         alloc += 1 << incr;
yading@10:     }
yading@10:     for(;;) {
yading@10:         /* look for the subband with the largest signal to mask ratio */
yading@10:         max_sb = -1;
yading@10:         max_ch = -1;
yading@10:         max_smr = INT_MIN;
yading@10:         for(ch=0;ch<s->nb_channels;ch++) {
yading@10:             for(i=0;i<s->sblimit;i++) {
yading@10:                 if (smr[ch][i] > max_smr && subband_status[ch][i] != SB_NOMORE) {
yading@10:                     max_smr = smr[ch][i];
yading@10:                     max_sb = i;
yading@10:                     max_ch = ch;
yading@10:                 }
yading@10:             }
yading@10:         }
yading@10:         if (max_sb < 0)
yading@10:             break;
yading@10:         av_dlog(NULL, "current=%d max=%d max_sb=%d max_ch=%d alloc=%d\n",
yading@10:                 current_frame_size, max_frame_size, max_sb, max_ch,
yading@10:                 bit_alloc[max_ch][max_sb]);
yading@10: 
yading@10:         /* find alloc table entry (XXX: not optimal, should use
yading@10:            pointer table) */
yading@10:         alloc = s->alloc_table;
yading@10:         for(i=0;i<max_sb;i++) {
yading@10:             alloc += 1 << alloc[0];
yading@10:         }
yading@10: 
yading@10:         if (subband_status[max_ch][max_sb] == SB_NOTALLOCATED) {
yading@10:             /* nothing was coded for this band: add the necessary bits */
yading@10:             incr = 2 + nb_scale_factors[s->scale_code[max_ch][max_sb]] * 6;
yading@10:             incr += total_quant_bits[alloc[1]];
yading@10:         } else {
yading@10:             /* increments bit allocation */
yading@10:             b = bit_alloc[max_ch][max_sb];
yading@10:             incr = total_quant_bits[alloc[b + 1]] -
yading@10:                 total_quant_bits[alloc[b]];
yading@10:         }
yading@10: 
yading@10:         if (current_frame_size + incr <= max_frame_size) {
yading@10:             /* can increase size */
yading@10:             b = ++bit_alloc[max_ch][max_sb];
yading@10:             current_frame_size += incr;
yading@10:             /* decrease smr by the resolution we added */
yading@10:             smr[max_ch][max_sb] = smr1[max_ch][max_sb] - quant_snr[alloc[b]];
yading@10:             /* max allocation size reached ? */
yading@10:             if (b == ((1 << alloc[0]) - 1))
yading@10:                 subband_status[max_ch][max_sb] = SB_NOMORE;
yading@10:             else
yading@10:                 subband_status[max_ch][max_sb] = SB_ALLOCATED;
yading@10:         } else {
yading@10:             /* cannot increase the size of this subband */
yading@10:             subband_status[max_ch][max_sb] = SB_NOMORE;
yading@10:         }
yading@10:     }
yading@10:     *padding = max_frame_size - current_frame_size;
yading@10:     av_assert0(*padding >= 0);
yading@10: }
yading@10: 
yading@10: /*
yading@10:  * Output the mpeg audio layer 2 frame. Note how the code is small
yading@10:  * compared to other encoders :-)
yading@10:  */
yading@10: static void encode_frame(MpegAudioContext *s,
yading@10:                          unsigned char bit_alloc[MPA_MAX_CHANNELS][SBLIMIT],
yading@10:                          int padding)
yading@10: {
yading@10:     int i, j, k, l, bit_alloc_bits, b, ch;
yading@10:     unsigned char *sf;
yading@10:     int q[3];
yading@10:     PutBitContext *p = &s->pb;
yading@10: 
yading@10:     /* header */
yading@10: 
yading@10:     put_bits(p, 12, 0xfff);
yading@10:     put_bits(p, 1, 1 - s->lsf); /* 1 = mpeg1 ID, 0 = mpeg2 lsf ID */
yading@10:     put_bits(p, 2, 4-2);  /* layer 2 */
yading@10:     put_bits(p, 1, 1); /* no error protection */
yading@10:     put_bits(p, 4, s->bitrate_index);
yading@10:     put_bits(p, 2, s->freq_index);
yading@10:     put_bits(p, 1, s->do_padding); /* use padding */
yading@10:     put_bits(p, 1, 0);             /* private_bit */
yading@10:     put_bits(p, 2, s->nb_channels == 2 ? MPA_STEREO : MPA_MONO);
yading@10:     put_bits(p, 2, 0); /* mode_ext */
yading@10:     put_bits(p, 1, 0); /* no copyright */
yading@10:     put_bits(p, 1, 1); /* original */
yading@10:     put_bits(p, 2, 0); /* no emphasis */
yading@10: 
yading@10:     /* bit allocation */
yading@10:     j = 0;
yading@10:     for(i=0;i<s->sblimit;i++) {
yading@10:         bit_alloc_bits = s->alloc_table[j];
yading@10:         for(ch=0;ch<s->nb_channels;ch++) {
yading@10:             put_bits(p, bit_alloc_bits, bit_alloc[ch][i]);
yading@10:         }
yading@10:         j += 1 << bit_alloc_bits;
yading@10:     }
yading@10: 
yading@10:     /* scale codes */
yading@10:     for(i=0;i<s->sblimit;i++) {
yading@10:         for(ch=0;ch<s->nb_channels;ch++) {
yading@10:             if (bit_alloc[ch][i])
yading@10:                 put_bits(p, 2, s->scale_code[ch][i]);
yading@10:         }
yading@10:     }
yading@10: 
yading@10:     /* scale factors */
yading@10:     for(i=0;i<s->sblimit;i++) {
yading@10:         for(ch=0;ch<s->nb_channels;ch++) {
yading@10:             if (bit_alloc[ch][i]) {
yading@10:                 sf = &s->scale_factors[ch][i][0];
yading@10:                 switch(s->scale_code[ch][i]) {
yading@10:                 case 0:
yading@10:                     put_bits(p, 6, sf[0]);
yading@10:                     put_bits(p, 6, sf[1]);
yading@10:                     put_bits(p, 6, sf[2]);
yading@10:                     break;
yading@10:                 case 3:
yading@10:                 case 1:
yading@10:                     put_bits(p, 6, sf[0]);
yading@10:                     put_bits(p, 6, sf[2]);
yading@10:                     break;
yading@10:                 case 2:
yading@10:                     put_bits(p, 6, sf[0]);
yading@10:                     break;
yading@10:                 }
yading@10:             }
yading@10:         }
yading@10:     }
yading@10: 
yading@10:     /* quantization & write sub band samples */
yading@10: 
yading@10:     for(k=0;k<3;k++) {
yading@10:         for(l=0;l<12;l+=3) {
yading@10:             j = 0;
yading@10:             for(i=0;i<s->sblimit;i++) {
yading@10:                 bit_alloc_bits = s->alloc_table[j];
yading@10:                 for(ch=0;ch<s->nb_channels;ch++) {
yading@10:                     b = bit_alloc[ch][i];
yading@10:                     if (b) {
yading@10:                         int qindex, steps, m, sample, bits;
yading@10:                         /* we encode 3 sub band samples of the same sub band at a time */
yading@10:                         qindex = s->alloc_table[j+b];
yading@10:                         steps = ff_mpa_quant_steps[qindex];
yading@10:                         for(m=0;m<3;m++) {
yading@10:                             sample = s->sb_samples[ch][k][l + m][i];
yading@10:                             /* divide by scale factor */
yading@10: #ifdef USE_FLOATS
yading@10:                             {
yading@10:                                 float a;
yading@10:                                 a = (float)sample * scale_factor_inv_table[s->scale_factors[ch][i][k]];
yading@10:                                 q[m] = (int)((a + 1.0) * steps * 0.5);
yading@10:                             }
yading@10: #else
yading@10:                             {
yading@10:                                 int q1, e, shift, mult;
yading@10:                                 e = s->scale_factors[ch][i][k];
yading@10:                                 shift = scale_factor_shift[e];
yading@10:                                 mult = scale_factor_mult[e];
yading@10: 
yading@10:                                 /* normalize to P bits */
yading@10:                                 if (shift < 0)
yading@10:                                     q1 = sample << (-shift);
yading@10:                                 else
yading@10:                                     q1 = sample >> shift;
yading@10:                                 q1 = (q1 * mult) >> P;
yading@10:                                 q[m] = ((q1 + (1 << P)) * steps) >> (P + 1);
yading@10:                             }
yading@10: #endif
yading@10:                             if (q[m] >= steps)
yading@10:                                 q[m] = steps - 1;
yading@10:                             av_assert2(q[m] >= 0 && q[m] < steps);
yading@10:                         }
yading@10:                         bits = ff_mpa_quant_bits[qindex];
yading@10:                         if (bits < 0) {
yading@10:                             /* group the 3 values to save bits */
yading@10:                             put_bits(p, -bits,
yading@10:                                      q[0] + steps * (q[1] + steps * q[2]));
yading@10:                         } else {
yading@10:                             put_bits(p, bits, q[0]);
yading@10:                             put_bits(p, bits, q[1]);
yading@10:                             put_bits(p, bits, q[2]);
yading@10:                         }
yading@10:                     }
yading@10:                 }
yading@10:                 /* next subband in alloc table */
yading@10:                 j += 1 << bit_alloc_bits;
yading@10:             }
yading@10:         }
yading@10:     }
yading@10: 
yading@10:     /* padding */
yading@10:     for(i=0;i<padding;i++)
yading@10:         put_bits(p, 1, 0);
yading@10: 
yading@10:     /* flush */
yading@10:     flush_put_bits(p);
yading@10: }
yading@10: 
yading@10: static int MPA_encode_frame(AVCodecContext *avctx, AVPacket *avpkt,
yading@10:                             const AVFrame *frame, int *got_packet_ptr)
yading@10: {
yading@10:     MpegAudioContext *s = avctx->priv_data;
yading@10:     const int16_t *samples = (const int16_t *)frame->data[0];
yading@10:     short smr[MPA_MAX_CHANNELS][SBLIMIT];
yading@10:     unsigned char bit_alloc[MPA_MAX_CHANNELS][SBLIMIT];
yading@10:     int padding, i, ret;
yading@10: 
yading@10:     for(i=0;i<s->nb_channels;i++) {
yading@10:         filter(s, i, samples + i, s->nb_channels);
yading@10:     }
yading@10: 
yading@10:     for(i=0;i<s->nb_channels;i++) {
yading@10:         compute_scale_factors(s->scale_code[i], s->scale_factors[i],
yading@10:                               s->sb_samples[i], s->sblimit);
yading@10:     }
yading@10:     for(i=0;i<s->nb_channels;i++) {
yading@10:         psycho_acoustic_model(s, smr[i]);
yading@10:     }
yading@10:     compute_bit_allocation(s, smr, bit_alloc, &padding);
yading@10: 
yading@10:     if ((ret = ff_alloc_packet2(avctx, avpkt, MPA_MAX_CODED_FRAME_SIZE)) < 0)
yading@10:         return ret;
yading@10: 
yading@10:     init_put_bits(&s->pb, avpkt->data, avpkt->size);
yading@10: 
yading@10:     encode_frame(s, bit_alloc, padding);
yading@10: 
yading@10:     if (frame->pts != AV_NOPTS_VALUE)
yading@10:         avpkt->pts = frame->pts - ff_samples_to_time_base(avctx, avctx->delay);
yading@10: 
yading@10:     avpkt->size = put_bits_count(&s->pb) / 8;
yading@10:     *got_packet_ptr = 1;
yading@10:     return 0;
yading@10: }
yading@10: 
yading@10: static const AVCodecDefault mp2_defaults[] = {
yading@10:     { "b",    "128k" },
yading@10:     { NULL },
yading@10: };
yading@10: 
yading@10: AVCodec ff_mp2_encoder = {
yading@10:     .name                  = "mp2",
yading@10:     .type                  = AVMEDIA_TYPE_AUDIO,
yading@10:     .id                    = AV_CODEC_ID_MP2,
yading@10:     .priv_data_size        = sizeof(MpegAudioContext),
yading@10:     .init                  = MPA_encode_init,
yading@10:     .encode2               = MPA_encode_frame,
yading@10:     .sample_fmts           = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S16,
yading@10:                                                             AV_SAMPLE_FMT_NONE },
yading@10:     .supported_samplerates = (const int[]){
yading@10:         44100, 48000,  32000, 22050, 24000, 16000, 0
yading@10:     },
yading@10:     .channel_layouts       = (const uint64_t[]){ AV_CH_LAYOUT_MONO,
yading@10:                                                  AV_CH_LAYOUT_STEREO,
yading@10:                                                  0 },
yading@10:     .long_name             = NULL_IF_CONFIG_SMALL("MP2 (MPEG audio layer 2)"),
yading@10:     .defaults              = mp2_defaults,
yading@10: };