Subversion Repositories Kolibri OS

Rev

Blame | Last modification | View Log | RSS feed

  1. /*
  2.  * G.726 ADPCM audio codec
  3.  * Copyright (c) 2004 Roman Shaposhnik
  4.  *
  5.  * This is a very straightforward rendition of the G.726
  6.  * Section 4 "Computational Details".
  7.  *
  8.  * This file is part of FFmpeg.
  9.  *
  10.  * FFmpeg is free software; you can redistribute it and/or
  11.  * modify it under the terms of the GNU Lesser General Public
  12.  * License as published by the Free Software Foundation; either
  13.  * version 2.1 of the License, or (at your option) any later version.
  14.  *
  15.  * FFmpeg is distributed in the hope that it will be useful,
  16.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18.  * Lesser General Public License for more details.
  19.  *
  20.  * You should have received a copy of the GNU Lesser General Public
  21.  * License along with FFmpeg; if not, write to the Free Software
  22.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  23.  */
  24. #include <limits.h>
  25.  
  26. #include "libavutil/channel_layout.h"
  27. #include "libavutil/opt.h"
  28. #include "avcodec.h"
  29. #include "internal.h"
  30. #include "get_bits.h"
  31. #include "put_bits.h"
  32.  
  33. /**
  34.  * G.726 11bit float.
  35.  * G.726 Standard uses rather odd 11bit floating point arithmetic for
  36.  * numerous occasions. It's a mystery to me why they did it this way
  37.  * instead of simply using 32bit integer arithmetic.
  38.  */
  39. typedef struct Float11 {
  40.     uint8_t sign;   /**< 1bit sign */
  41.     uint8_t exp;    /**< 4bit exponent */
  42.     uint8_t mant;   /**< 6bit mantissa */
  43. } Float11;
  44.  
  45. static inline Float11* i2f(int i, Float11* f)
  46. {
  47.     f->sign = (i < 0);
  48.     if (f->sign)
  49.         i = -i;
  50.     f->exp = av_log2_16bit(i) + !!i;
  51.     f->mant = i? (i<<6) >> f->exp : 1<<5;
  52.     return f;
  53. }
  54.  
  55. static inline int16_t mult(Float11* f1, Float11* f2)
  56. {
  57.         int res, exp;
  58.  
  59.         exp = f1->exp + f2->exp;
  60.         res = (((f1->mant * f2->mant) + 0x30) >> 4);
  61.         res = exp > 19 ? res << (exp - 19) : res >> (19 - exp);
  62.         return (f1->sign ^ f2->sign) ? -res : res;
  63. }
  64.  
  65. static inline int sgn(int value)
  66. {
  67.     return (value < 0) ? -1 : 1;
  68. }
  69.  
  70. typedef struct G726Tables {
  71.     const int* quant;         /**< quantization table */
  72.     const int16_t* iquant;    /**< inverse quantization table */
  73.     const int16_t* W;         /**< special table #1 ;-) */
  74.     const uint8_t* F;         /**< special table #2 */
  75. } G726Tables;
  76.  
  77. typedef struct G726Context {
  78.     AVClass *class;
  79.     G726Tables tbls;    /**< static tables needed for computation */
  80.  
  81.     Float11 sr[2];      /**< prev. reconstructed samples */
  82.     Float11 dq[6];      /**< prev. difference */
  83.     int a[2];           /**< second order predictor coeffs */
  84.     int b[6];           /**< sixth order predictor coeffs */
  85.     int pk[2];          /**< signs of prev. 2 sez + dq */
  86.  
  87.     int ap;             /**< scale factor control */
  88.     int yu;             /**< fast scale factor */
  89.     int yl;             /**< slow scale factor */
  90.     int dms;            /**< short average magnitude of F[i] */
  91.     int dml;            /**< long average magnitude of F[i] */
  92.     int td;             /**< tone detect */
  93.  
  94.     int se;             /**< estimated signal for the next iteration */
  95.     int sez;            /**< estimated second order prediction */
  96.     int y;              /**< quantizer scaling factor for the next iteration */
  97.     int code_size;
  98.     int little_endian;  /**< little-endian bitstream as used in aiff and Sun AU */
  99. } G726Context;
  100.  
  101. static const int quant_tbl16[] =                  /**< 16kbit/s 2bits per sample */
  102.            { 260, INT_MAX };
  103. static const int16_t iquant_tbl16[] =
  104.            { 116, 365, 365, 116 };
  105. static const int16_t W_tbl16[] =
  106.            { -22, 439, 439, -22 };
  107. static const uint8_t F_tbl16[] =
  108.            { 0, 7, 7, 0 };
  109.  
  110. static const int quant_tbl24[] =                  /**< 24kbit/s 3bits per sample */
  111.            {  7, 217, 330, INT_MAX };
  112. static const int16_t iquant_tbl24[] =
  113.            { INT16_MIN, 135, 273, 373, 373, 273, 135, INT16_MIN };
  114. static const int16_t W_tbl24[] =
  115.            { -4,  30, 137, 582, 582, 137,  30, -4 };
  116. static const uint8_t F_tbl24[] =
  117.            { 0, 1, 2, 7, 7, 2, 1, 0 };
  118.  
  119. static const int quant_tbl32[] =                  /**< 32kbit/s 4bits per sample */
  120.            { -125,  79, 177, 245, 299, 348, 399, INT_MAX };
  121. static const int16_t iquant_tbl32[] =
  122.          { INT16_MIN,   4, 135, 213, 273, 323, 373, 425,
  123.                  425, 373, 323, 273, 213, 135,   4, INT16_MIN };
  124. static const int16_t W_tbl32[] =
  125.            { -12,  18,  41,  64, 112, 198, 355, 1122,
  126.             1122, 355, 198, 112,  64,  41,  18, -12};
  127. static const uint8_t F_tbl32[] =
  128.            { 0, 0, 0, 1, 1, 1, 3, 7, 7, 3, 1, 1, 1, 0, 0, 0 };
  129.  
  130. static const int quant_tbl40[] =                  /**< 40kbit/s 5bits per sample */
  131.            { -122, -16,  67, 138, 197, 249, 297, 338,
  132.               377, 412, 444, 474, 501, 527, 552, INT_MAX };
  133. static const int16_t iquant_tbl40[] =
  134.          { INT16_MIN, -66,  28, 104, 169, 224, 274, 318,
  135.                  358, 395, 429, 459, 488, 514, 539, 566,
  136.                  566, 539, 514, 488, 459, 429, 395, 358,
  137.                  318, 274, 224, 169, 104,  28, -66, INT16_MIN };
  138. static const int16_t W_tbl40[] =
  139.            {   14,  14,  24,  39,  40,  41,   58,  100,
  140.               141, 179, 219, 280, 358, 440,  529,  696,
  141.               696, 529, 440, 358, 280, 219,  179,  141,
  142.               100,  58,  41,  40,  39,  24,   14,   14 };
  143. static const uint8_t F_tbl40[] =
  144.            { 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 2, 3, 4, 5, 6, 6,
  145.              6, 6, 5, 4, 3, 2, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0 };
  146.  
  147. static const G726Tables G726Tables_pool[] =
  148.            {{ quant_tbl16, iquant_tbl16, W_tbl16, F_tbl16 },
  149.             { quant_tbl24, iquant_tbl24, W_tbl24, F_tbl24 },
  150.             { quant_tbl32, iquant_tbl32, W_tbl32, F_tbl32 },
  151.             { quant_tbl40, iquant_tbl40, W_tbl40, F_tbl40 }};
  152.  
  153.  
  154. /**
  155.  * Para 4.2.2 page 18: Adaptive quantizer.
  156.  */
  157. static inline uint8_t quant(G726Context* c, int d)
  158. {
  159.     int sign, exp, i, dln;
  160.  
  161.     sign = i = 0;
  162.     if (d < 0) {
  163.         sign = 1;
  164.         d = -d;
  165.     }
  166.     exp = av_log2_16bit(d);
  167.     dln = ((exp<<7) + (((d<<7)>>exp)&0x7f)) - (c->y>>2);
  168.  
  169.     while (c->tbls.quant[i] < INT_MAX && c->tbls.quant[i] < dln)
  170.         ++i;
  171.  
  172.     if (sign)
  173.         i = ~i;
  174.     if (c->code_size != 2 && i == 0) /* I'm not sure this is a good idea */
  175.         i = 0xff;
  176.  
  177.     return i;
  178. }
  179.  
  180. /**
  181.  * Para 4.2.3 page 22: Inverse adaptive quantizer.
  182.  */
  183. static inline int16_t inverse_quant(G726Context* c, int i)
  184. {
  185.     int dql, dex, dqt;
  186.  
  187.     dql = c->tbls.iquant[i] + (c->y >> 2);
  188.     dex = (dql>>7) & 0xf;        /* 4bit exponent */
  189.     dqt = (1<<7) + (dql & 0x7f); /* log2 -> linear */
  190.     return (dql < 0) ? 0 : ((dqt<<dex) >> 7);
  191. }
  192.  
  193. static int16_t g726_decode(G726Context* c, int I)
  194. {
  195.     int dq, re_signal, pk0, fa1, i, tr, ylint, ylfrac, thr2, al, dq0;
  196.     Float11 f;
  197.     int I_sig= I >> (c->code_size - 1);
  198.  
  199.     dq = inverse_quant(c, I);
  200.  
  201.     /* Transition detect */
  202.     ylint = (c->yl >> 15);
  203.     ylfrac = (c->yl >> 10) & 0x1f;
  204.     thr2 = (ylint > 9) ? 0x1f << 10 : (0x20 + ylfrac) << ylint;
  205.     tr= (c->td == 1 && dq > ((3*thr2)>>2));
  206.  
  207.     if (I_sig)  /* get the sign */
  208.         dq = -dq;
  209.     re_signal = c->se + dq;
  210.  
  211.     /* Update second order predictor coefficient A2 and A1 */
  212.     pk0 = (c->sez + dq) ? sgn(c->sez + dq) : 0;
  213.     dq0 = dq ? sgn(dq) : 0;
  214.     if (tr) {
  215.         c->a[0] = 0;
  216.         c->a[1] = 0;
  217.         for (i=0; i<6; i++)
  218.             c->b[i] = 0;
  219.     } else {
  220.         /* This is a bit crazy, but it really is +255 not +256 */
  221.         fa1 = av_clip_intp2((-c->a[0]*c->pk[0]*pk0)>>5, 8);
  222.  
  223.         c->a[1] += 128*pk0*c->pk[1] + fa1 - (c->a[1]>>7);
  224.         c->a[1] = av_clip(c->a[1], -12288, 12288);
  225.         c->a[0] += 64*3*pk0*c->pk[0] - (c->a[0] >> 8);
  226.         c->a[0] = av_clip(c->a[0], -(15360 - c->a[1]), 15360 - c->a[1]);
  227.  
  228.         for (i=0; i<6; i++)
  229.             c->b[i] += 128*dq0*sgn(-c->dq[i].sign) - (c->b[i]>>8);
  230.     }
  231.  
  232.     /* Update Dq and Sr and Pk */
  233.     c->pk[1] = c->pk[0];
  234.     c->pk[0] = pk0 ? pk0 : 1;
  235.     c->sr[1] = c->sr[0];
  236.     i2f(re_signal, &c->sr[0]);
  237.     for (i=5; i>0; i--)
  238.         c->dq[i] = c->dq[i-1];
  239.     i2f(dq, &c->dq[0]);
  240.     c->dq[0].sign = I_sig; /* Isn't it crazy ?!?! */
  241.  
  242.     c->td = c->a[1] < -11776;
  243.  
  244.     /* Update Ap */
  245.     c->dms += (c->tbls.F[I]<<4) + ((- c->dms) >> 5);
  246.     c->dml += (c->tbls.F[I]<<4) + ((- c->dml) >> 7);
  247.     if (tr)
  248.         c->ap = 256;
  249.     else {
  250.         c->ap += (-c->ap) >> 4;
  251.         if (c->y <= 1535 || c->td || abs((c->dms << 2) - c->dml) >= (c->dml >> 3))
  252.             c->ap += 0x20;
  253.     }
  254.  
  255.     /* Update Yu and Yl */
  256.     c->yu = av_clip(c->y + c->tbls.W[I] + ((-c->y)>>5), 544, 5120);
  257.     c->yl += c->yu + ((-c->yl)>>6);
  258.  
  259.     /* Next iteration for Y */
  260.     al = (c->ap >= 256) ? 1<<6 : c->ap >> 2;
  261.     c->y = (c->yl + (c->yu - (c->yl>>6))*al) >> 6;
  262.  
  263.     /* Next iteration for SE and SEZ */
  264.     c->se = 0;
  265.     for (i=0; i<6; i++)
  266.         c->se += mult(i2f(c->b[i] >> 2, &f), &c->dq[i]);
  267.     c->sez = c->se >> 1;
  268.     for (i=0; i<2; i++)
  269.         c->se += mult(i2f(c->a[i] >> 2, &f), &c->sr[i]);
  270.     c->se >>= 1;
  271.  
  272.     return av_clip(re_signal << 2, -0xffff, 0xffff);
  273. }
  274.  
  275. static av_cold int g726_reset(G726Context *c)
  276. {
  277.     int i;
  278.  
  279.     c->tbls = G726Tables_pool[c->code_size - 2];
  280.     for (i=0; i<2; i++) {
  281.         c->sr[i].mant = 1<<5;
  282.         c->pk[i] = 1;
  283.     }
  284.     for (i=0; i<6; i++) {
  285.         c->dq[i].mant = 1<<5;
  286.     }
  287.     c->yu = 544;
  288.     c->yl = 34816;
  289.  
  290.     c->y = 544;
  291.  
  292.     return 0;
  293. }
  294.  
  295. #if CONFIG_ADPCM_G726_ENCODER
  296. static int16_t g726_encode(G726Context* c, int16_t sig)
  297. {
  298.     uint8_t i;
  299.  
  300.     i = av_mod_uintp2(quant(c, sig/4 - c->se), c->code_size);
  301.     g726_decode(c, i);
  302.     return i;
  303. }
  304.  
  305. /* Interfacing to the libavcodec */
  306.  
  307. static av_cold int g726_encode_init(AVCodecContext *avctx)
  308. {
  309.     G726Context* c = avctx->priv_data;
  310.  
  311.     if (avctx->strict_std_compliance > FF_COMPLIANCE_UNOFFICIAL &&
  312.         avctx->sample_rate != 8000) {
  313.         av_log(avctx, AV_LOG_ERROR, "Sample rates other than 8kHz are not "
  314.                "allowed when the compliance level is higher than unofficial. "
  315.                "Resample or reduce the compliance level.\n");
  316.         return AVERROR(EINVAL);
  317.     }
  318.     if (avctx->sample_rate <= 0) {
  319.         av_log(avctx, AV_LOG_ERROR, "Invalid sample rate %d\n",
  320.                avctx->sample_rate);
  321.         return AVERROR(EINVAL);
  322.     }
  323.  
  324.     if(avctx->channels != 1){
  325.         av_log(avctx, AV_LOG_ERROR, "Only mono is supported\n");
  326.         return AVERROR(EINVAL);
  327.     }
  328.  
  329.     if (avctx->bit_rate)
  330.         c->code_size = (avctx->bit_rate + avctx->sample_rate/2) / avctx->sample_rate;
  331.  
  332.     c->code_size = av_clip(c->code_size, 2, 5);
  333.     avctx->bit_rate = c->code_size * avctx->sample_rate;
  334.     avctx->bits_per_coded_sample = c->code_size;
  335.  
  336.     g726_reset(c);
  337.  
  338.     /* select a frame size that will end on a byte boundary and have a size of
  339.        approximately 1024 bytes */
  340.     avctx->frame_size = ((int[]){ 4096, 2736, 2048, 1640 })[c->code_size - 2];
  341.  
  342.     return 0;
  343. }
  344.  
  345. static int g726_encode_frame(AVCodecContext *avctx, AVPacket *avpkt,
  346.                              const AVFrame *frame, int *got_packet_ptr)
  347. {
  348.     G726Context *c = avctx->priv_data;
  349.     const int16_t *samples = (const int16_t *)frame->data[0];
  350.     PutBitContext pb;
  351.     int i, ret, out_size;
  352.  
  353.     out_size = (frame->nb_samples * c->code_size + 7) / 8;
  354.     if ((ret = ff_alloc_packet2(avctx, avpkt, out_size, 0)) < 0)
  355.         return ret;
  356.     init_put_bits(&pb, avpkt->data, avpkt->size);
  357.  
  358.     for (i = 0; i < frame->nb_samples; i++)
  359.         put_bits(&pb, c->code_size, g726_encode(c, *samples++));
  360.  
  361.     flush_put_bits(&pb);
  362.  
  363.     avpkt->size = out_size;
  364.     *got_packet_ptr = 1;
  365.     return 0;
  366. }
  367.  
  368. #define OFFSET(x) offsetof(G726Context, x)
  369. #define AE AV_OPT_FLAG_AUDIO_PARAM | AV_OPT_FLAG_ENCODING_PARAM
  370. static const AVOption options[] = {
  371.     { "code_size", "Bits per code", OFFSET(code_size), AV_OPT_TYPE_INT, { .i64 = 4 }, 2, 5, AE },
  372.     { NULL },
  373. };
  374.  
  375. static const AVClass g726_class = {
  376.     .class_name = "g726",
  377.     .item_name  = av_default_item_name,
  378.     .option     = options,
  379.     .version    = LIBAVUTIL_VERSION_INT,
  380. };
  381.  
  382. static const AVCodecDefault defaults[] = {
  383.     { "b", "0" },
  384.     { NULL },
  385. };
  386.  
  387. AVCodec ff_adpcm_g726_encoder = {
  388.     .name           = "g726",
  389.     .long_name      = NULL_IF_CONFIG_SMALL("G.726 ADPCM"),
  390.     .type           = AVMEDIA_TYPE_AUDIO,
  391.     .id             = AV_CODEC_ID_ADPCM_G726,
  392.     .priv_data_size = sizeof(G726Context),
  393.     .init           = g726_encode_init,
  394.     .encode2        = g726_encode_frame,
  395.     .capabilities   = AV_CODEC_CAP_SMALL_LAST_FRAME,
  396.     .sample_fmts    = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S16,
  397.                                                      AV_SAMPLE_FMT_NONE },
  398.     .priv_class     = &g726_class,
  399.     .defaults       = defaults,
  400. };
  401. #endif
  402.  
  403. #if CONFIG_ADPCM_G726_DECODER || CONFIG_ADPCM_G726LE_DECODER
  404. static av_cold int g726_decode_init(AVCodecContext *avctx)
  405. {
  406.     G726Context* c = avctx->priv_data;
  407.  
  408.     if(avctx->channels > 1){
  409.         avpriv_request_sample(avctx, "Decoding more than one channel");
  410.         return AVERROR_PATCHWELCOME;
  411.     }
  412.     avctx->channels       = 1;
  413.     avctx->channel_layout = AV_CH_LAYOUT_MONO;
  414.  
  415.     c->little_endian = !strcmp(avctx->codec->name, "g726le");
  416.  
  417.     c->code_size = avctx->bits_per_coded_sample;
  418.     if (c->code_size < 2 || c->code_size > 5) {
  419.         av_log(avctx, AV_LOG_ERROR, "Invalid number of bits %d\n", c->code_size);
  420.         return AVERROR(EINVAL);
  421.     }
  422.     g726_reset(c);
  423.  
  424.     avctx->sample_fmt = AV_SAMPLE_FMT_S16;
  425.  
  426.     return 0;
  427. }
  428.  
  429. static int g726_decode_frame(AVCodecContext *avctx, void *data,
  430.                              int *got_frame_ptr, AVPacket *avpkt)
  431. {
  432.     AVFrame *frame     = data;
  433.     const uint8_t *buf = avpkt->data;
  434.     int buf_size = avpkt->size;
  435.     G726Context *c = avctx->priv_data;
  436.     int16_t *samples;
  437.     GetBitContext gb;
  438.     int out_samples, ret;
  439.  
  440.     out_samples = buf_size * 8 / c->code_size;
  441.  
  442.     /* get output buffer */
  443.     frame->nb_samples = out_samples;
  444.     if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
  445.         return ret;
  446.     samples = (int16_t *)frame->data[0];
  447.  
  448.     init_get_bits(&gb, buf, buf_size * 8);
  449.  
  450.     while (out_samples--)
  451.         *samples++ = g726_decode(c, c->little_endian ?
  452.                                     get_bits_le(&gb, c->code_size) :
  453.                                     get_bits(&gb, c->code_size));
  454.  
  455.     if (get_bits_left(&gb) > 0)
  456.         av_log(avctx, AV_LOG_ERROR, "Frame invalidly split, missing parser?\n");
  457.  
  458.     *got_frame_ptr = 1;
  459.  
  460.     return buf_size;
  461. }
  462.  
  463. static void g726_decode_flush(AVCodecContext *avctx)
  464. {
  465.     G726Context *c = avctx->priv_data;
  466.     g726_reset(c);
  467. }
  468. #endif
  469.  
  470. #if CONFIG_ADPCM_G726_DECODER
  471. AVCodec ff_adpcm_g726_decoder = {
  472.     .name           = "g726",
  473.     .long_name      = NULL_IF_CONFIG_SMALL("G.726 ADPCM"),
  474.     .type           = AVMEDIA_TYPE_AUDIO,
  475.     .id             = AV_CODEC_ID_ADPCM_G726,
  476.     .priv_data_size = sizeof(G726Context),
  477.     .init           = g726_decode_init,
  478.     .decode         = g726_decode_frame,
  479.     .flush          = g726_decode_flush,
  480.     .capabilities   = AV_CODEC_CAP_DR1,
  481. };
  482. #endif
  483.  
  484. #if CONFIG_ADPCM_G726LE_DECODER
  485. AVCodec ff_adpcm_g726le_decoder = {
  486.     .name           = "g726le",
  487.     .type           = AVMEDIA_TYPE_AUDIO,
  488.     .id             = AV_CODEC_ID_ADPCM_G726LE,
  489.     .priv_data_size = sizeof(G726Context),
  490.     .init           = g726_decode_init,
  491.     .decode         = g726_decode_frame,
  492.     .flush          = g726_decode_flush,
  493.     .capabilities   = AV_CODEC_CAP_DR1,
  494.     .long_name      = NULL_IF_CONFIG_SMALL("G.726 ADPCM little-endian"),
  495. };
  496. #endif
  497.